Interim safety and immunogenicity of COVID-19 omicron BA.1 variant-containing vaccine in children in the USA: an open-label non-randomised phase 3 trial

BACKGROUND

Variant-containing mRNA vaccines for COVID-19 to broaden protection against SARS-CoV-2 variants are recommended based on findings in adults. We report interim safety and immunogenicity of an omicron BA.1 variant-containing (mRNA-1273.214) primary vaccination series and booster dose in paediatric populations.

METHODS

This open-label, two-part, non-randomised phase 3 trial enrolled participants aged 6 months to 5 years at 24 US study sites. Eligible participants were generally healthy or had stable chronic conditions, without known SARS-CoV-2 infection in the previous 90 days. Individuals who were acutely ill or febrile 1 day before or at the screening visit or those who previously received other COVID-19 vaccines (except mRNA-1273 for part 2) were excluded. In part 1, SARS-CoV-2-vaccine-naive participants received two-dose mRNA-1273.214 (25 μg; omicron BA.1 and ancestral Wuhan-Hu-1 mRNA) primary series. In part 2, participants who previously completed the two-dose mRNA-1273 (25 μg) primary series in KidCOVE (NCT04796896) received a mRNA-1273.214 (10 μg) booster dose. Primary study outcomes were safety and reactogenicity of the mRNA-1273.214 primary series (part 1) or booster dose (part 2) as well as the inferred effectiveness of mRNA-1273.214 based on immune responses against ancestral SARS-CoV-2 (D614G) and omicron BA.1 variant at 28 days post-primary series (part 1) or post-booster dose (part 2). The safety set included participants who received at least one dose of the study vaccine; the immunogenicity set included those who provided immunogenicity samples. Interim safety and immunogenicity are summarised in this analysis as of the data cutoff date (Dec 5, 2022). This trial is registered with ClinicalTrials.gov, NCT05436834.

FINDINGS

Between June 21, 2022, and Dec 5, 2022, 179 participants received one or more doses of mRNA-1273.214 primary series (part 1) and 539 received a mRNA-1273.214 booster dose (part 2). The safety profile within 28 days after either dose of the mRNA-1273.214 primary series and the booster dose was consistent with that of the mRNA-1273 primary series in this age group, with no new safety concerns or vaccine-related serious adverse events observed. At 28 days after primary series dose 2 and the booster dose, both mRNA-1273.214 primary series (day 57, including all participants with or without evidence of prior SARS-CoV-2 infection at baseline) and booster (day 29, including participants without evidence of prior SARS-CoV-2 infection at baseline) elicited responses that were superior against omicron-BA.1 (geometric mean ratio part 1: 25·4 [95% CI 20·1-32·1] and part 2: 12·5 [11·0-14·3]) and non-inferior against D614G (part 1: 0·8 [0·7-1·0] and part 2: 3·1 [2·8-3·5]), compared with neutralising antibody responses induced by the mRNA-1273 primary series (in a historical comparator group).

INTERPRETATION

mRNA-1273.214 was immunogenic against BA.1 and D614G in children aged 6 months to 5 years, with a comparable safety profile to mRNA-1273, when given as a two-dose primary series or a booster dose. These results are aligned with the US Centers for Disease Control and Prevention recommendations for the use of variant-containing vaccines for continued protection against the emerging variants of SARS-CoV-2.

FUNDING

Moderna.

COVID-19 vaccine perspectives and uptake among university students three years into the pandemic

BACKGROUND

University students have been uniquely impacted by the COVID-19 pandemic for the past three years (2020-2023). Understanding their COVID-19 perspectives, beliefs, and vaccine uptake may help to improve future vaccine initiatives and education.

METHODS

A cross sectional, confidential, online survey was conducted at four universities in Pennsylvania in spring 2023 to assess undergraduate, graduate, and professional students' perspectives regarding their knowledge of COVID-19 vaccines, importance of COVID-19 vaccines and mandates, number of doses of COVID-19 vaccine received including the recent BA.4/BA.5 bivalent booster, where they were vaccinated, receipt of influenza vaccine, and sources of information used to make decisions about COVID-19 vaccine.

RESULTS

Vaccination for COVID-19 was considered important by 75 % of 2223 students surveyed; 68 % agreed with mandating COVID-19 vaccine. Over 89 % were fully COVID-19 vaccinated (≥2 doses), 65 % were up-to-date (≥3 doses), but only 35 % had received the BA.4/BA.5 booster. Students who considered COVID-19 vaccine important were generally older, female, and non-business majors. Higher rates of up-to-date COVID-19 vaccination were found in those who received influenza vaccine in 2022-2023, females, Asians, doctoral or professional students, those attending larger universities, non-US residents, and those interested in learning more about COVID-19 vaccines. Most trusted sources of information on COVID-19 vaccines were the Centers for Disease Control and Prevention, healthcare providers, and parents; the least trusted sources were social media, television, and the internet.

CONCLUSIONS

The majority of university students agreed that COVID-19 vaccination is important and supported COVID-19 mandates. While the rate of fully vaccinated and up-to-date students was similar to the US adult population, the latter rate needs improvement. Receipt of the BA.4/BA.5 booster was particularly low. Further education is needed to improve vaccine knowledge, especially as we move to periodic boosters. Business majors, males, and younger students may benefit from increased on-campus vaccine education initiatives.

Emerging heterologous mRNA-based booster strategies within the COVID-19 vaccine landscape

Messenger RNA (mRNA)-based vaccine platforms used for the development of mRNA-1273 and BNT162b2 have provided a robust adaptable approach to offer protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, as variants of concern (VoCs), such as omicron and associated sub-variants, emerge, boosting strategies must also adapt to keep pace with the changing landscape. Heterologous vaccination regimens involving the administration of booster vaccines different than the primary vaccination series offer a practical, effective, and safe approach to continue to reduce the global burden of coronavirus disease 2019 (COVID-19). To understand the immunogenicity, effectiveness, and safety of heterologous mRNA-based vaccination strategies, relevant clinical and real-world observational studies were identified and summarized. Overall, heterologous boosting strategies with mRNA-based vaccines that are currently available and those in development will play an important global role in protecting individuals from COVID-19 caused by emerging VoCs.

Neutralizing Antibody Response following a Third Dose of the mRNA-1273 Vaccine among Cancer Patients

Cancer patients are at an increased risk of morbidity and mortality from SARS-CoV-2 infection and have a decreased immune response to vaccination. We conducted a study measuring both the neutralizing and total antibodies in cancer patients following a third dose of the mRNA-1273 COVID-19 vaccine. Immune responses were measured with an enzyme-linked immunosorbent assay (ELISA) and neutralization assays. Kruskal-Wallis tests were used to evaluate the association between patient characteristics and neutralization geometric mean titers (GMTs), and paired t-tests were used to compare the GMTs between different timepoints. Spearman correlation coefficients were calculated to determine the correlation between total antibody and neutralization GMTs. Among 238 adults diagnosed with cancer, a third dose of mRNA-1273 resulted in a 37-fold increase in neutralization GMT 28 days post-vaccination and maintained a 14.6-fold increase at 6 months. Patients with solid tumors or lymphoid cancer had the highest and lowest neutralization GMTs, respectively, at both 28 days and 6 months post-dose 3. While total antibody GMTs in lymphoid patients continued to increase, other cancer types showed decreases in titers between 28 days and 6 months post-dose 3. A strong correlation (p < 0.001) was found between total antibody and neutralization GMTs. The third dose of mRNA-1273 was able to elicit a robust neutralizing antibody response in cancer patients, which remained for 6 months after administration. Lymphoid cancer patients can benefit most from this third dose, as it was shown to continue to increase total antibody GMTs 6 months after vaccination.

Efficacy and Safety of an mRNA-Based RSV PreF Vaccine in Older Adults

BACKGROUND

Respiratory syncytial virus (RSV) can cause substantial morbidity and mortality among older adults. An mRNA-based RSV vaccine, mRNA-1345, encoding the stabilized RSV prefusion F glycoprotein, is under clinical investigation.

METHODS

In this ongoing, randomized, double-blind, placebo-controlled, phase 2-3 trial, we randomly assigned, in a 1:1 ratio, adults 60 years of age or older to receive one dose of mRNA-1345 (50 μg) or placebo. The two primary efficacy end points were the prevention of RSV-associated lower respiratory tract disease with at least two signs or symptoms and with at least three signs or symptoms. A key secondary efficacy end point was the prevention of RSV-associated acute respiratory disease. Safety was also assessed.

RESULTS

Overall, 35,541 participants were assigned to receive the mRNA-1345 vaccine (17,793 participants) or placebo (17,748). The median follow-up was 112 days (range, 1 to 379). The primary analyses were conducted when at least 50% of the anticipated cases of RSV-associated lower respiratory tract disease had occurred. Vaccine efficacy was 83.7% (95.88% confidence interval [CI], 66.0 to 92.2) against RSV-associated lower respiratory tract disease with at least two signs or symptoms and 82.4% (96.36% CI, 34.8 to 95.3) against the disease with at least three signs or symptoms. Vaccine efficacy was 68.4% (95% CI, 50.9 to 79.7) against RSV-associated acute respiratory disease. Protection was observed against both RSV subtypes (A and B) and was generally consistent across subgroups defined according to age and coexisting conditions. Participants in the mRNA-1345 group had a higher incidence than those in the placebo group of solicited local adverse reactions (58.7% vs. 16.2%) and of systemic adverse reactions (47.7% vs. 32.9%); most reactions were mild to moderate in severity and were transient. Serious adverse events occurred in 2.8% of the participants in each trial group.

CONCLUSIONS

A single dose of the mRNA-1345 vaccine resulted in no evident safety concerns and led to a lower incidence of RSV-associated lower respiratory tract disease and of RSV-associated acute respiratory disease than placebo among adults 60 years of age or older. (Funded by Moderna; ConquerRSV ClinicalTrials.gov number, NCT05127434.).

Perceptions of the Availability of Personal Protective Equipment and Its Association With Burnout Among US Healthcare Personnel During the SARS-CoV-2 Pandemic, 2020-2021

OBJECTIVE

The aim of the study is to explore associations among personal protective equipment (PPE) availability, workplace environment, and burnout among US healthcare personnel during the COVID-19 pandemic.

METHODS

The study used an online healthcare provider (HCP) survey (December 2020-February 2021) regarding PPE confidence, availability, burnout, and workplace environment.

RESULTS

Lack of appropriate PPE was reported by 27% of 799 US HCP surveyed. Burnout, reported by 77% of HCP, was more likely among females, those with fewer years of professional experience, and those with a higher desire to quit, and less likely for those who perceived PPE was adequate or their employer took all steps to minimize workplace risks.

CONCLUSIONS

This study suggests that lack of adequate PPE can lead to HCP burnout, which may result in employees quitting. A pandemic preparedness plan that includes adequate PPE is essential for HCP well-being, patient health, and employer fiscal health.

COVID-19 vaccine uptake before and after a vaccine mandate at a major academic hospital: Trends by race/ethnicity and level of patient contact

OBJECTIVES

To assess vaccine coverage rates before and after implementation of a COVID-19 vaccine mandate among Health care Personnel (HCP) and demographic characteristics associated with vaccine uptake Design, Setting, and Participants: Cohort study conducted among 10,889 hospital employees followed from Dec 16, 2020 - October 31, 2021, at a large academic hospital in Philadelphia.

MAIN OUTCOME AND MEASURES

Time to COVID-19 vaccination and vaccine series completion rates before and after implementation of a COVID-19 vaccine mandate based on age, gender, race/ethnicity, and level of patient contact/occupational group.

RESULTS

The vaccination series completion rate was 86.0% prior to mandate announcement, and increased to 98.7% after mandate implementation. Rates before mandate announcement were highest among Asians (96.2%), Whites (94.0%), males (89.7%), employees ≥ 65 years of age (95.2%), and employees with direct patient care (physicians, 99.0%, and nurses, 93.3%). Hospital educational initiatives (including Town Halls and discussions with Black and Hispanic employees with the lowest vaccination rates) appeared to improve uptake. The largest increase in series completion after mandate announcement occurred among Blacks, those of other/multiracial backgrounds, and Hispanics (35.6%, 22.4%, and 10.8%, respectively) as well as those with some or no direct patient contact (24.5% and 18.3%, respectively). Medical or religious exemptions were approved for 64 (<0.6%) employees and 38 (<0.4%) left their positions (8 voluntary, 30 involuntary) specifically due to the COVID-19 vaccine mandate. No clinically meaningful differences by age, gender, or race/ethnicity for those who were vaccinated under the mandate versus those who left their positions were noted.

CONCLUSIONS AND RELEVANCE

These results suggest that while mandates may be challenging to institutions and enforcement unpopular, they play an important role in reducing hesitancy and securing high vaccination rates among HCP, a group at high risk of COVID-19 given their employment and who can be a source of disease transmission to patients.

Best Practices for Implementation of an Employee Health COVID-19 Vaccine Clinic-A Model for Future Pandemic Preparedness

OBJECTIVES

The aims of the study are to determine best practices from two large-scale, academic medical centers' employee coronavirus 2019 (COVID-19) vaccination clinics and to apply them to create scalable modules for rapid administration of 10,000 vaccinations.

METHODS

The weekly number of COVID-19 vaccine doses administered was captured. Processes were compared to determine best practices, which informed the scalable financial model.

RESULTS

Within the first 3 months, more than 60,000 COVID-19 vaccine doses were administered, and 70% of employees were fully vaccinated in 4 months with more than 95% by the vaccine mandate deadline. The estimated cost of delivering one dose was $29.95 ($299,505/10,000) compared with $35-$39 per dose when delivered by an on-site retail pharmacy.

CONCLUSIONS

Successful, safe, and rapid delivery of more than 60,000 COVID-19 vaccine doses in 3 months is practical and scalable. Learnings go beyond COVID-19 and can be applied to future outbreaks/pandemics.

Coronavirus disease 2019 (COVID-19) vaccine hesitancy among physicians, physician assistants, nurse practitioners, and nurses in two academic hospitals in Philadelphia

OBJECTIVE

To evaluate coronavirus disease 2019 (COVID-19) vaccine hesitancy among healthcare personnel (HCP) with significant clinical exposure to COVID-19 at 2 large, academic hospitals in Philadelphia, Pennsylvania.

DESIGN, SETTING, AND PARTICIPANTS

HCP were surveyed in November-December 2020 about their intention to receive the COVID-19 vaccine.

METHODS

The survey measured the intent among HCP to receive a COVID-19 vaccine, timing of vaccination, and reasons for or against vaccination. Among patient-facing HCP, multivariate regression evaluated the associations between healthcare positions (medical doctor, nurse practitioner or physician assistant, and registered nurse) and vaccine hesitancy (intending to decline, delay, or were unsure about vaccination), adjusting for demographic characteristics, reasons why or why not to receive the vaccine, and prior receipt of routine vaccines.

RESULTS

Among 5,929 HCP (2,253 medical doctors [MDs] and doctors of osteopathy [DOs], 582 nurse practitioners [NPs], 158 physician assistants [PAs], and 2,936 nurses), a higher proportion of nurses (47.3%) were COVID-vaccine hesitant compared with 30.0% of PAs and NPs and 13.1% of MDs and DOs. The most common reasons for vaccine hesitancy included concerns about side effects, the newness of the vaccines, and lack of vaccine knowledge. Regardless of position, Black HCP were more hesitant than White HCP (odds ratio [OR], ∼5) and females were more hesitant than males (OR, ∼2).

CONCLUSIONS

Although most clinical HCP intended to receive a COVID-19 vaccine, intention varied by healthcare position. Consistent with other studies, hesitancy was also significantly associated with race or ethnicity across all positions. These results highlight the importance of understanding and effectively addressing reasons for hesitancy, especially among frontline HCP who are at increased risk of COVID exposure and play a critical role in recommending vaccines to patients.

Prevention of measles, mumps and rubella: 40 years of global experience with M-M-RII

Measles, mumps, and rubella are highly contagious diseases that caused significant global mortality and morbidity in the pre-vaccine era. Since its first approval in the United States over 40 years ago, M-M-R_II has been used in >75 countries for prevention of these diseases. The vaccine has been part of immunization programs that have achieved dramatic global reductions in case numbers and mortality rates, as well as the elimination of measles and rubella in several countries and regions. This report summarizes over four decades of global safety, immunogenicity, efficacy, and effectiveness data for the vaccine. We include studies on the use of M-M-R_II in different age groups, concomitant use with other routine childhood vaccines, administration via different routes, persistence of immunity, and vaccine effectiveness during outbreaks of measles and mumps. We conclude that M-M-R_II is well tolerated and has shown consistently high performance during routine use in multiple countries, in randomized controlled trials with diverse designs, and in outbreak settings, including use as measles postexposure prophylaxis. Physicians, parents, and the public can continue to have a high degree of confidence in the use of M-M-R_II as a vital part of global public health programs.

Factors Associated With COVID-19 Vaccine Receipt by Health Care Personnel at a Major Academic Hospital During the First Months of Vaccine Availability

Importance

Several COVID-19 vaccines have been authorized in the US, yet preliminary evidence suggests high levels of vaccine hesitancy and wide racial, ethnic, and socioeconomic disparities in uptake.

Objective

To assess COVID-19 vaccine acceptance among health care personnel (HCP) during the first 4 months of availability in a large academic hospital, compare acceptance with previously measured vaccine hesitancy, and describe racial, ethnic, and socioeconomic disparities in vaccine uptake.

Design, Setting, and Participants

This cross-sectional study included 12 610 HCP who were offered COVID-19 vaccination at a major academic hospital in Philadelphia between December 16, 2020, and April 16, 2021.

Exposures

For each HCP, data were collected on occupational category, age, sex, race and ethnicity (Asian or Pacific Islander, Black or African American [Black], Hispanic, White, and multiracial), and social vulnerability index (SVI) at the zip code of residence.

Main Outcomes and Measures

Vaccine uptake by HCP at the employee vaccination clinic.

Results

The study population included 4173 men (34.8%) and 7814 women (65.2%) (623 without data). A total of 1480 were Asian or Pacific Islander (12.4%); 2563 (21.6%), Black; 452 (3.8%), Hispanic; 7086 (59.6%), White; and 192 (1.6%), multiracial; 717 had no data for race and ethnicity. The mean (SD) age was 40.9 (12.4) years, and 9573 (76.0%) received at least 1 vaccine dose during the first 4 months of vaccine availability. Adjusted for age, sex, job position, and SVI, Black (relative risk [RR], 0.69; 95% CI, 0.66-0.72) and multiracial (RR, 0.80; 95% CI, 0.73-0.89) HCP were less likely to receive vaccine compared with White HCP. When stratified by job position, Black nurses (n = 189; 62.8%), Black HCP with some patient contact (n = 466; 49.9%), and Black HCP with no patient contact (n = 636; 56.3%) all had lower vaccine uptake compared with their White and Asian or Pacific Islander counterparts. Similarly, multiracial HCP with some (n = 26; 52.0%) or no (n = 48; 58.5%) patient contact had lower vaccine uptake. In contrast, Black physicians were just as likely to receive the vaccine as physicians of other racial and ethnic groups.

Conclusions and Relevance

In this cross-sectional study, more than two-thirds of HCP at a large academic hospital in Philadelphia received a COVID-19 vaccine within 4 months of vaccine availability. Although racial, ethnic, and socioeconomic disparities were seen in vaccine uptake, no such disparities were found among physicians. Better understanding of factors driving these disparities may help improve uptake.

Evaluation of the Safety and Immunogenicity of M-M-RII (Combination Measles-mumps-rubella Vaccine): Clinical Trials of Healthy Children and Adults Published Between 2010 and 2019

BACKGROUND

The safety and immunogenicity of M-M-RII (measles, mumps and rubella virus vaccine live, Merck & Co., Inc., West Point, PA)-the only combined measles, mumps and rubella vaccine licensed for use in the United States-were previously reported in pre- and postlicensure clinical trials conducted from 1988 to 2009. M-M-RII continues to be evaluated as a comparator in clinical trials of other vaccines. Here, we review safety and efficacy data from more recent clinical trials of M-M-RII.

METHODS

We performed a systematic literature review of trials using M-M-RII published from 2010 to 2019.

RESULTS

In the 15 studies that met the inclusion criteria, a total of 12,032 subjects were vaccinated: 7667 persons received a first dose only, 2137 participated in 2-dose studies (128 received 1 dose and 2009 received both) and 2063 received a single dose of M-M-RII as their second dose. Dose number was not specified for 165 participants, ≥6 years old, in 2 studies in which a single dose of M-M-RII was administered. Similar to previous reports, M-M-RII was well tolerated and immunogenic when administered alone or concomitantly with other routinely recommended vaccinations. The most common adverse events included transient injection site pain and fever. Serious adverse events were extremely rare, with only 4 probable or potential vaccine-related events reported among the 12,032 participating subjects.

CONCLUSIONS

In trials published from 2010 to 2019, M-M-RII continued to be safe and immunogenic in all age groups studied. These data, along with the results of earlier trials, indicate that the performance of the vaccine has been consistent across more than 30 years of postlicensure studies.

Racial/Ethnic Differences in COVID-19 Vaccine Hesitancy Among Health Care Workers in 2 Large Academic Hospitals

IMPORTANCE

Significant differences in hesitancy to receive COVID-19 vaccination by race/ethnicity have been observed in several settings. Racial/ethnic differences in COVID-19 vaccine hesitancy among health care workers (HCWs), who face occupational and community exposure to COVID-19, have not been well described.

OBJECTIVE

To assess hesitancy to COVID-19 vaccination among HCWs across different racial/ethnic groups and assess factors associated with vaccine hesitancy.

DESIGN, SETTING, AND PARTICIPANTS

This survey study was conducted among HCWs from 2 large academic hospitals (ie, a children's hospital and an adult hospital) over a 3-week period in November and December 2020. Eligible participants were HCWs with and without direct patient contact. A 3-step hierarchical multivariable logistic regression was used to evaluate associations between race/ethnicity and vaccine hesitancy controlling for demographic characteristics, employment characteristics, COVID-19 exposure risk, and being up to date with routine vaccinations. Data were analyzed from February through March 2021.

MAIN OUTCOMES AND MEASURES

Vaccine hesitancy, defined as not planning on, being unsure about, or planning to delay vaccination, served as the outcome.

RESULTS

Among 34 865 HCWs eligible for this study, 12 034 individuals (34.5%) completed the survey and 10 871 individuals (32.2%) completed the survey and reported their race/ethnicity. Among 10 866 of these HCWs with data on sex, 8362 individuals (76.9%) were women, and among 10 833 HCWs with age data, 5923 individuals (54.5%) were younger than age 40 years. (Percentages for demographic and clinical characteristics are among the number of respondents for each type of question.) There were 8388 White individuals (77.2%), 882 Black individuals (8.1%), 845 Asian individuals (7.8%), and 449 individuals with other or mixed race/ethnicity (4.1%), and there were 307 Hispanic or Latino individuals (2.8%). Vaccine hesitancy was highest among Black HCWs (732 individuals [83.0%]) and Hispanic or Latino HCWs (195 individuals [63.5%]) (P < .001). Among 5440 HCWs with vaccine hesitancy, reasons given for hesitancy included concerns about side effects (4737 individuals [87.1%]), newness of the vaccine (4306 individuals [79.2%]), and lack of vaccine knowledge (4091 individuals [75.2%]). The adjusted odds ratio (aOR) for vaccine hesitancy was 4.98 (95% CI, 4.11-6.03) among Black HCWs, 2.10 (95% CI, 1.63-2.70) among Hispanic or Latino HCWs, 1.48 (95% CI, 1.21-1.82) among HCWs with other or mixed race/ethnicity, and 1.47 (95% CI, 1.26-1.71) among Asian HCWs compared with White HCWs (P < .001). The aOR was decreased among Black HCWs when adjusting for employment characteristics and COVID-19 exposure risk (aOR, 4.87; 95% CI, 3.96-6.00; P < .001) and being up to date with prior vaccines (aOR, 4.48; 95% CI, 3.62-5.53; P < .001) but not among HCWs with other racial/ethnic backgrounds.

CONCLUSIONS AND RELEVANCE

This study found that vaccine hesitancy before the authorization of the COVID-19 vaccine was increased among Black, Hispanic or Latino, and Asian HCWs compared with White HCWs. These findings suggest that interventions focused on addressing vaccine hesitancy among HCWs are needed.

Current and future vaccine clinical research with the licensed 2-, 4-, and 9-valent VLP HPV vaccines: What's ongoing, what's needed?

Prophylactic HPV vaccination has been a great public health success. For >20 years, clinical trials were conducted with the 2-, 4-, and/or 9-valent vaccines in young-adult females, mid-adult women, males, and adolescents. In all studies, the vaccines were highly efficacious, immunogenic, and well tolerated. Following vaccine licensure and utilization in national vaccine programs globally (real-world settings primarily in high income countries), numerous studies demonstrated that the vaccines continue to have an excellent safety profile and have dramatically reduced the incidence of genital warts, HPV vaccine-type prevalence, and precancerous lesions. Thirty-eight clinical trials with the currently licensed HPV vaccines are ongoing. Key questions being addressed in new trials include: efficacy against persistent infection and immunogenicity of a 1-dose regimen; efficacy of 3 doses in 20-45-year-old females; use in postpartum women and immunocompromised individuals (HIV, liver and kidney transplants); dose sparing via intradermal administration; use in combination with a PD1 monoclonal antibody in patients with cervical cancer; impact on recurrent disease in women undergoing cervical conization; persistence of protection; and use to prevent oropharyngeal cancer. Additional clinical research that should be conducted includes: long-term follow-up, particularly of 1- and 2-dose regimens; further evaluation of flexible 2-dose regimens; immunogenicity of 1- or 2-dose regimens in persons ≥15 years old and immunocompromised populations; safety and immunogenicity of 1 or 2 doses in children <9 years old; assessment of the vaccine in the prevention of transmission; interchangeability with newer HPV vaccines; additional concomitant use studies; and prevention of penile cancer and recurrent respiratory papillomatosis.

Economic Value of Lost Productivity Attributable to Human Papillomavirus Cancer Mortality in the United States

Objectives: To estimate years of potential life lost (YPLL) and present value of future lost productivity (PVFLP) associated with premature mortality due to HPV-attributable cancers, specifically those targeted by nonavalent HPV (9vHPV) vaccination, in the United States (US) before vaccine use. Methods: YPLL was estimated from the reported number of deaths in 2017 due to HPV-related cancers, the proportion attributable to 9vHPV-targeted types, and age- and sex-specific US life expectancy. PVFLP was estimated as the product of YPLL by age- and sex-specific probability of labor force participation, annual wage, value of non-market labor, and fringe benefits markup factor. Results: An estimated 7,085 HPV-attributable cancer deaths occurred in 2017 accounting for 154,954 YPLL, with 5,450 deaths (77%) and 121,226 YPLL (78%) attributable to 9vHPV-targeted types. The estimated PVFLP was $3.3 billion for cancer deaths attributable to 9vHPV-targeted types (86% from women). The highest productivity burden was associated with cervical cancer in women and anal and oropharyngeal cancers in men. Conclusions: HPV-attributable cancer deaths are associated with a substantial economic burden in the US, much of which could be vaccine preventable.

Perspectives on the receipt of a COVID-19 vaccine: A survey of employees in two large hospitals in Philadelphia

Background

Health care personnel have been identified by the ACIP as a priority group for COVID-19 vaccination. We conducted a survey in November-December 2020 at two large, academic hospitals in Philadelphia to evaluate the intention of hospital employees to be vaccinated.

Methods

The survey was sent electronically to all employees (clinical and nonclinical staff) at a children’s hospital and an adult hospital. The survey was voluntary and confidential. Questions focused on plans to receive a COVID-19 vaccine when available, reasons why employees would/would not get vaccinated, when employees planned to be vaccinated, vaccine safety and efficacy features that would be acceptable, and past history of receipt of other vaccines by the employee and family. Responses were analyzed using univariate and multiple logistic regression methods.

Results

A total of 12,034 hospital employees completed the survey (a 34.5% response rate). Overall, 63.7% of employees reported that they planned to receive a COVID-19 vaccine, 26.3% were unsure, and 10.0% did not plan to be vaccinated. Over 80% of those unsure or unwilling to be vaccinated expressed concerns about vaccine side effects and the vaccines’ newness. In multivariable logistic regression, persons planning to take a COVID-19 vaccine were more likely to be older, male, more educated, Asian or White, up-to-date on vaccinations, without direct patient contact, and tested for COVID-19 in the past. No significant difference in intention to be vaccinated was found between those with higher versus lower levels of exposure to COVID-19 patients or the number of previous exposures to patients with COVID-19.

Conclusions

While the majority of hospital employees are planning to receive a COVID-19 vaccine, many are unsure or not planning to do so. Further education of hospital employees about the safety, efficacy, and value of the currently available COVID-19 vaccines is critical to vaccine acceptance in this population.

1390. Effectiveness of M-M-R® II in outbreaks - a systematic literature review of real-world observational studies

Background

M-M-R^® II was approved in the US in 1978 and has been used globally for over 40 years. Widespread use of M-M-R^® II has resulted in important declines in incidence, morbidity, and mortality of measles, mumps, and rubella in the US and other countries. While vaccine immunogenicity and efficacy were established in multiple placebo-controlled trials of each vaccine component, there are limited studies on vaccine effectiveness (VE) of M-M-R^® II. This systematic literature review was conducted to summarize the VE of M-M-R^® II from real-world observational studies.

Methods

The literature search was conducted in Medline and Embase (through May 2019), and grey literature sources (through July 2019). All publications and findings in English language were screened by two independent reviewers. The study characteristics and VE results were extracted for each study.

Results

Ten full-text publications related to VE of M-M-R^® II were all identified from outbreak investigations and mainly in the US (n=8, sample size=318 - 20,496).

For measles outbreaks (n=4), VE ranged from 71% to 96% in different age groups. Among high school students, VE of ≥1-dose of M-M-R^® II was 94-96%. Among young adolescents, the incremental VE of ≥2-dose vs. 1-dose was 94.1%. When M-M-R^® II was used as post-exposure prophylaxis within 72 hours of exposure during an outbreak, the VE was 83.4% among children 6 months to 19 years old. In another study among infants 6-14 months old, VE was 71% against laboratory-confirmed measles.

Among mumps outbreaks, the VE of 1-dose, 2-dose, and ≥1-dose M-M-R^® II compared to unvaccinated was 83-84%, 80-89%, 83-86% respectively. Three studies evaluating the effectiveness of a third dose of M-M-R^® II showed an incremental mumps VE of 60-88% for 3-dose vs. ≤ 2-dose. One study found that individuals who had received a 2^nd dose of M-M-R^® II ≥13 years (vs. < 13 years) before the outbreak had higher risk for contracting mumps.

No study reported VE of M-M-R^® II in a rubella outbreak.

Conclusion

M-M-R^® II was found to be effective against measles and mumps during outbreaks. More effectiveness studies are warranted to further address questions on the relationship of VE and time since vaccination as well as the effectiveness of a third dose of M-M-R^® II for measles or mumps outbreak control.

Disclosures

Se Li, PhD, Merck & Co., Inc. (Employee, Shareholder) Barbara J. Kuter, PhD, MPH, Merck (Other Financial or Material Support, Former employee) Elvira Schmidt, MSc, Certara (Employee of Certara, paid contractor to Merck) (Employee, Other Financial or Material Support) Elizabeth Richardson, BS, Merck Sharp & Dohme Corp. (Employee) Louise P. Saldutti, PhD, Mercfk & Co., Inc (Employee) Neumann Monika, Information Specialist, Certara (Employee, Employee of Certara, who was paid contractor to Merck.) Linnea Koller, n/a, Merck (Employee, Other Financial or Material Support, Employee of Certara who was paid contractor to Merck) Manica Agrawal, n/a, Certara (Employee)Merck (Grant/Research Support) Manjiri D. Pawaskar, PhD, Merck & Co., Inc (Employee, Shareholder)

The use of antibiotics in the treatment of pediatric varicella patients: real-world evidence from the multi-country MARVEL study in Latin America & Europe

Background

Varicella is a highly contagious childhood disease. Generally benign, serious complications necessitating antibiotic use may occur. The objective of this study was to characterize the rate, appropriateness and patterns of real-world antibiotic prescribing for management of varicella-associated complications, prior to universal varicella vaccination (UVV) implementation.

Methods

Pooled, post-hoc analysis of 5 international, multicenter, retrospective chart reviews studies (Argentina, Hungary, Mexico, Peru, Poland). Inpatient and outpatient primary pediatric (1–14 years) varicella cases, diagnosed between 2009 and 2016, were eligible. Outcomes, assessed descriptively, included varicella-associated complications and antibiotic use. Three antibiotic prescribing scenarios were defined based on complication profile in chart: evidence of microbiologically confirmed bacterial infection (Scenario A); insufficient evidence confirming microbiological confirmation (Scenario B); no evidence of microbiological confirmation (Scenario C). Stratification was performed by patient status (inpatient vs. outpatient) and country.

Results

Four hundred one outpatients and 386 inpatients were included. Mean (SD) outpatient age was 3.6 (2.8) years; inpatient age was 3.1 (2.8) years. Male gender was predominant. Overall, 12.2% outpatients reported ≥1 infectious complication, 3.7% ≥1 bacterial infection, and 0.5% ≥1 microbiologically confirmed infection; inpatient complication rates were 78.8, 33.2 and 16.6%, respectively. Antibiotics were prescribed to 12.7% of outpatients and 68.9% of inpatients. Among users, β-lactamases (class), and clindamycin (agent), dominated prescriptions. Scenario A was assigned to 3.9% (outpatients) vs 13.2% (inpatients); Scenario B: 2.0% vs. 6.0%; Scenario C: 94.1% vs. 80.8%.

Conclusions

High rates of infectious complications and antibiotic use are reported, with low rates of microbiological confirmation suggesting possible antibiotic misuse for management of varicella complications.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-7071-z) contains supplementary material, which is available to authorized users.

Varicella healthcare resource utilization in middle income countries: a pooled analysis of the multi-country MARVEL study in Latin America & Europe

Varicella is a mild and self-limited illness in children, but can result in significant healthcare resource utilization (HCRU). To quantify/contrast varicella-associated HCRU in five middle-income countries (Hungary, Poland, Argentina, Mexico, and Peru) where universal varicella vaccination was unimplemented, charts were retrospectively reviewed among 1-14 year-olds. Data were obtained on management of primary varicella between 2009-2016, including outpatient/inpatient visits, allied healthcare contacts, tests/procedures, and medications. These results are contrasted across countries, and a regression model is fit to extrapolated country-level costs as a function of gross domestic product (GDP). A total of 401 outpatients and 386 inpatients were included. Significant differences between countries were observed in the number of skin lesions among outpatients, ranging from 5.3% to 25.4% of patients with ≥250 lesions. Among inpatients, results were less variable. Average ambulatory medical visits ranged from 1.1 to 2.2. Average hospital stay ranged from 3.6 to 6.8 days. Use of tests/procedures was infrequent in outpatients, except in Argentina (13.3%); among inpatients, a test/procedure was ordered for 81.3% of patients, without regional variation. Prescription medications were administered in 44.4% of outpatients (range 9.3%-80.0%), and in 86% of inpatients (range 70.4%-94.9%). Total estimated spending on varicella treatment in the absence of vaccination was predicted from income levels (GDP) with an exponential function (R² = 0.89). This study demonstrates that substantial HCRU is associated with varicella resulting in significant public health burden that could be alleviated through the use of varicella vaccination. Differences observed between countries possibly reflect treatment guidelines, healthcare resource availabilities and physician practices.

Safety and immunogenicity of VAQTA® in children 12-to-23 months of age with and without administration of other US pediatric vaccines

Safety and immunogenicity data from 5 clinical trials conducted in the US in children 12-to-23 months old where HAVi was administered alone or concomitantly with other pediatric vaccines (M-M-R®II, Varivax®, TRIPEDIA®, Prevnar®, ProQuad®, PedvaxHIB®, and INFANRIX®) were combined. Among 4,374 participants receiving ≥ 1 dose of HAVi, 4,222 (97%) had safety follow-up and the proportions reporting adverse events (AE) were comparable when administered alone (69.4%) or concomitantly with other pediatric vaccines (71.1%). The most common solicited injection-site AEs were pain/tenderness (Postdose 1: 25.8%; Postdose 2: 26.1%) and redness (Postdose 1: 13.6%; Postdose 2: 15.1%). The most common vaccine-related systemic AEs were fever (≥ 100.4ºF, 12.2%) and irritability (8.1%). Serious AEs (SAEs) were observed at a rate of 0.4%; 0.1% were considered vaccine-related. No deaths were reported within 14 days following a dose of HAVi. These integrated analyses also showed that protective antibody concentrations were elicited in 100% of toddlers after two doses and 92% after a single dose, regardless of whether HAVi was given concomitantly with other vaccines or alone. These results demonstrate that HAVi was well-tolerated whether given alone or concomitantly with other vaccines, with a low incidence of vaccine-related SAEs. HAVi was immunogenic in this age group regardless of whether administered with or without other pediatric vaccines and whether 1 or 2 doses were administered. HAVi did not impact the immune response to other vaccines. These data continue to support the routine use of HAVi with other pediatric vaccines in children ≥ 12 months of age.

Economic burden of varicella in children 1-12 years of age in Argentina, 2009-2014

BACKGROUND

In Argentina, varicella vaccination was included in the national schedule for mandatory immunizations in 2015. The vaccine has been shown to substantially reduce the morbidity and mortality associated with the virus. The purpose of this study was to evaluate the clinical and economic burden associated with varicella in Argentina prior to vaccine introduction.

METHODS

This was a multi-center, retrospective chart review study among patients aged 1-12 years with a primary varicella diagnosis in 2009-2014 in Argentina. Healthcare resource utilization (HCRU) associated with varicella and its complications, unit costs, and work loss were used to estimate direct and indirect costs. All costs are presented in 2015 United States dollars (USD).

RESULTS

One hundred and fifty children with varicella were included (75 outpatients, 75 inpatients), with a mean age of 3.8 (SD = 2.4) and 2.9 (SD = 2.2) years, respectively. One or more complications were experienced by 28.0% of outpatients and 98.7% of inpatients, the most common being skin and soft tissue infections, pneumonia, sepsis, cerebellitis, and febrile seizure. HCRU estimates included use of over-the-counter (OTC) medications (58.7% outpatients, 94.7% inpatients), prescription medications (26.7% outpatients, 77.3% inpatients), tests/procedures (13.3% outpatients, 70.7% inpatients), and consultation with allied health professionals (1.3% outpatients, 32.0% inpatients). The average duration of hospital stay was 4.9 (95% CI = 4.2-5.7) days, and the average duration of ICU stay was 4.8 (95% CI = 1.6-14.1) days. The total combined direct and indirect cost per varicella case was 2947.7 USD (inpatients) and 322.7 USD (outpatients). The overall annual cost of varicella in Argentina for children aged ≤14 years in 2015 was estimated at 40,054,378.0 USD.

CONCLUSION

The clinical burden of varicella in Argentina was associated with utilization of significant amounts of healthcare resources, resulting in substantial economic costs. These costs should be reduced with the recent implementation of routine vaccination of children.

Economic burden of varicella in children 1-12 Years of age in Hungary, 2011-2015

Background

Although live-attenuated varicella-zoster virus (VZV) vaccines have been proven to be safe and effective in preventing varicella and real-word evidence shows routine childhood immunization programs are effective in dramatically reducing varicella associated morbidity and mortality, varicella vaccine is not included in the National Immunization Program (NIP) in Hungary. The purpose of this study was to evaluate the clinical and economic burden associated with varicella in Hungary.

Methods

This was a multicenter, retrospective, chart review study of patients aged 1–12 years with a primary varicella diagnosis between 2011 and 2015. Healthcare resource utilization (HCRU) associated with varicella, unit costs, and work loss were used to estimate direct and indirect costs. All costs are presented in 2015 HUF / Euros (€).

Results

156 children with varicella were included (75 outpatients, 81 inpatients), with a mean age of 4.4 (SD: 2.0) and 3.7 (SD: 2.1) years, respectively. One or more complications were reported by 12.0% of outpatients and 92.6% of inpatients, the most common being dehydration, skin and soft tissue infections, pneumonia, keratoconjunctivitis, and cerebellitis. HCRU estimates included use of over-the-counter (OTC) medications (96.0% outpatients, 53.1% inpatients), prescription medications (9.3% outpatients, 70.4% inpatients), tests/procedures (4.0% outpatients, 97.5% inpatients), and consultation with allied health professionals (2.7% outpatients, 30.9% inpatients). The average duration of hospital stay (inpatients) was 3.6 (95% CI: 3.2, 4.1) days. The total combined direct and indirect cost per varicella case was 228,146.7 Hungarian Forint (HUF)/€ 736.0 for inpatients and 49,790.6 HUF/€ 106.6 for outpatients. The overall annual cost of varicella in Hungary for children aged <15 years in 2015 was estimated at 1,903,332,524.3 HUF/ € 6,139,980.4.

Conclusion

Varicella is associated with substantial clinical burden in Hungary, resulting in the utilization of a significant amount of healthcare resources. These results support the need for routine vaccination of all healthy children to reduce the varicella-associated disease burden.

Impact and Effectiveness of the Quadrivalent Human Papillomavirus Vaccine: A Systematic Review of 10 Years of Real-world Experience

This systematic review assessed the global impact and effectiveness of quadrivalent human papillomavirus (HPV) vaccination on HPV infection and disease in real-world settings over a decade of use. Substantial reductions in HPV 6/11/16/18 infection, anogenital warts, and cervical lesions have been achieved.

Prophylactic human papillomavirus (HPV) vaccination programs constitute major public health initiatives worldwide. We assessed the global effect of quadrivalent HPV (4vHPV) vaccination on HPV infection and disease. PubMed and Embase were systematically searched for peer-reviewed articles from January 2007 through February 2016 to identify observational studies reporting the impact or effectiveness of 4vHPV vaccination on infection, anogenital warts, and cervical cancer or precancerous lesions. Over the last decade, the impact of HPV vaccination in real-world settings has become increasingly evident, especially among girls vaccinated before HPV exposure in countries with high vaccine uptake. Maximal reductions of approximately 90% for HPV 6/11/16/18 infection, approximately 90% for genital warts, approximately 45% for low-grade cytological cervical abnormalities, and approximately 85% for high-grade histologically proven cervical abnormalities have been reported. The full public health potential of HPV vaccination is not yet realized. HPV-related disease remains a significant source of morbidity and mortality in developing and developed nations, underscoring the need for HPV vaccination programs with high population coverage.

Analysis of safety data in children after receiving two doses of ProQuad® (MMRV)

BACKGROUND

In randomized clinical studies, over 11,800 children, 12 months to 6 years of age, were administered ProQuad(®), a combination measles, mumps, rubella, and varicella vaccine (MMRV). This paper describes the safety following a 2-dose regimen of MMRV administered to children in the second year of life.

METHODS

Safety data from five clinical studies were combined for all children who were scheduled to receive two doses of MMRV ∼3-6 months apart. All vaccinated children were followed for safety following each dose of MMRV.

RESULTS

Of 3112 children who received a first dose of MMRV, 2780 (89.3%) received a second dose of MMRV. Overall, 70.5% and 57.7% of children reported ≥1 adverse experiences following first and second doses of MMRV, respectively. Injection-site redness was statistically significantly higher postdose 2 than postdose 1, while injection-site pain/tenderness was statistically significantly higher postdose 1 compared to postdose 2. Rashes were statistically significantly lower postdose 2 compared to postdose 1. Ten febrile seizures (8 postdose 1, 2 postdose 2) were reported following MMRV vaccination. The incidence of febrile seizures postdose 1 of MMRV was 0.26% (8/3019) compared to 0.07% (2/2695) postdose 2 of MMRV.

CONCLUSIONS

Administration of two doses of MMRV has an acceptable safety profile in children 12 to 23 months of age. There is a small increase in the risk of febrile seizures following the first dose of MMRV as compared to the component vaccines, but the risk for any individual child is relatively low.

Safety and Immunogenicity of a Combination: Measles, Mumps, Rubella and Varicella Vaccine (ProQuad®)

BACKGROUND

A combination measles, mumps, rubella, and varicella vaccine (ProQuad, Merck & Co., Inc, West Point, PA) was evaluated in five clinical trials. Use of ProQuad would result in fewer injections for children and would facilitate universal immunization against all four diseases.

OBJECTIVE

To describe the combined results obtained from the studies conducted during the clinical development program for ProQuad.

METHODS

A total of 5833 healthy children, 12-23 months of age, and 399 healthy children, 4-6 years of age, received 1 or 2 doses of ProQuad in five controlled clinical trials. M-M-R II and VARIVAX were used as the control for most studies. Safety was evaluated for six weeks postvaccination and immunogenicity was assessed six weeks after each dose by a sensitive assay (ELISA or gpELISA).

RESULTS

A single dose of ProQuad in 12- to 23-month-old children was shown to be as immunogenic as a single dose of M-M-R II and VARIVAX and was generally well tolerated. ProQuad can be used concomitantly with other vaccines (hepatitis B and Hoemophilus influenzoe b). A higher rate of fever was reported after 1 dose of ProQuad compared to M-M-R II and VARIVAX, but fever episodes were transient without long-term sequelae. Both a 2-dose regimen of ProQuad in 12- to 23-month-olds and use of ProQuad in place of M-M-R II at 4-6 years were shown to be immunogenic and well tolerated. The incidence of adverse experiences following a second dose of ProQuad was lower than that following the initial dose.

CONCLUSIONS

A single dose of ProQuad is as immunogenic as M-M-R II and VARIVAX and is well tolerated in a 1- or 2-dose schedule. ProQuad should easily fit into the routine immunization schedule.

Concomitant administration of hepatitis A vaccine with measles/mumps/rubella/varicella and pneumococcal vaccines in healthy 12- to 23-month-old children

This open-label, multicenter, randomized, comparative study evaluated immunogenicity, safety and tolerability of concomitant (Group 1; n=330) vs. non-concomitant (Group 2; n=323) VAQTA™ (25U/0.5 mL) (hepatitis A vaccine; HAV) with ProQuad™ (measles/mumps/rubella/varicella; MMRV) and Prevnar™ (7-valent pneumococcal; PCV-7) in healthy, 12-23 mo old children. Group 1 received HAV/MMRV/PCV-7 concomitantly on Day 1 and second doses of HAV/MMRV at Week 24. Group 2 received MMRV/PCV-7 on Day 1, HAV at Weeks 6 and 30 and MMRV at Week 34. Hepatitis A seropositivity rate (SPR: ≥10 mIU/mL; 4 weeks postdose 2), varicella zoster-virus (VZV) SPR (≥5 gpELISA units/mL) and geometric mean titers (GMT) to S. pneumoniae were examined. Injection-site and systemic adverse experiences (AEs) and daily temperatures were collected. Hepatitis A SPR were 100% for Group 1 and 99.4% for Group 2 after two HAV doses; risk difference=0.7 (95%CI: -1.4,3.8, non-inferior) regardless of initial serostatus. VZV SPR was 93.3% for Group 1 and 98.3% for Group 2; risk difference=-5.1 (95%CI: -9.3, -1.4; non-inferior). S. pneumoniae GMT fold-difference (7 serotypes) ranged from 0.9 to 1.1; non-inferior. No statistically significant differences in the incidence of individual AEs were seen when HAV was administered concomitantly vs. non-concomitantly. Three (all Group 2 post-administration of MMRV/PCV-7) of 11 serious AEs were considered possibly vaccine-related: dehydration and gastroenteritis (same subject) on Day 52; febrile seizure on Day 9. No deaths were reported. Antibody responses to each vaccine given concomitantly were non-inferior to HAV given non-concomitantly with MMRV and PCV-7. Administration of HAV with PCV-7 and MMRV had an acceptable safety profile in 12- to 23-mo-old children.

Factors associated with receipt of two doses of varicella vaccine among adolescents in the United States

BACKGROUND

In 2006, routine two-dose varicella vaccination for all children was recommended, including a second dose catch-up program for older children and adolescents. Recent studies have shown that a second dose of the vaccine provides incremental protection against varicella disease.

METHODS

This study is a cross-sectional analysis of data collected in the National Immunization Survey-Teen 2010 combined with publicly available data related to state immunization requirements. Bivariate and multivariable logistic regression analyses were performed to examine individual-level and state-level factors associated with receipt of two doses of varicella vaccine among 10,542 adolescents 13 to 17 years of age with no history of varicella.

RESULTS

Overall, 58.1% of adolescents without any history of varicella had received two doses of varicella vaccine. Coverage varied widely among states, ranging from 19.7% in South Dakota to 85.3% in Rhode Island. In the multivariable model, receipt of two doses of varicella vaccine was significantly associated with younger age, higher maternal education level, private health insurance, more frequent health care visits, receipt of both quadrivalent meningococcal conjugate and tetanus, diphtheria, and acellular pertussis vaccinations, and residing in a state with two-dose policies for middle school entry. Vaccines for Children program-eligible adolescents were less likely to have received two doses.

CONCLUSION

Two-dose varicella vaccination coverage remained low among adolescents in 2010, despite the universal recommendation. Programs that are aimed specifically at Vaccines for Children program-eligible adolescents, state policies requiring two doses for middle school entry, and broad education and implementation of the adolescent vaccination platform may help to improve varicella vaccination coverage.

Evaluating the health impact of a public-private partnership: to reduce rotavirus disease in Nicaragua

The purpose of this article is to describe the RotaTeq(®) Nicaragua Partnership and the evaluation of the public health impact of the vaccine conducted by the partners, including the creation of a rotavirus surveillance program and a vaccine effectiveness assessment. The three main objectives of the partnership were to demonstrate that a new rotavirus vaccine could (1) be introduced rapidly in a developing country, (2) be successfully integrated into the existing vaccine delivery infrastructure, and (3) have a significant and measurable public health impact at the end of the 3-y program. The vaccine impact assessment required collaboration among partners with different areas of expertise, including the Nicaraguan Ministry of Health, Merck, local hospitals, government health clinics, laboratories, and a Technical Advisory Group. Through the partnership, RotaTeq(®) became available in a GAVI-eligible developing country, Nicaragua, in the same year it was approved in the United States. Vaccine coverage rapidly reached over > 90% of eligible Nicaraguan children. The impact assessment evaluated over 10,000 subjects and leveraged and enhanced the existing diarrheal surveillance infrastructure, ultimately providing the scientific community with some of the first real-world rotavirus vaccine effectiveness data from a developing country. The successful public-private partnership (PPP) was internationally recognized as a model for the rapid adoption of a new vaccine in a developing world setting. The model could be adapted to benefit other PPPs interested in demonstrating the impact of their own programs.

Age dependence of the risk of intussusception following [corrected] rhesus-human reassortant rotavirus tetravalent vaccine: is it beyond doubt?

The relation between the risk of intussusception and age at the time of receipt of the first dose of rhesus-human reassortant rotavirus tetravalent vaccine (RRV-TV) has been studied extensively on the basis of Centers for Disease Control and Prevention (CDC) matched case-control study data, using various statistical methods, including conditional logistic regression and quadratic smoothing splines. However, different conclusions have been reported in published analyses regarding the dependence of the risk of intussusception on age at first dose. The authors reanalyzed the CDC matched case-control data set using unrestricted and restricted quadratic smoothing spline methods for various exposure windows (i.e., intervals postvaccination). These analyses indicated that the use of different models may lead to different conclusions. The restricted quadratic smoothing spline with appropriately chosen knot locations showed a statistically significant increased risk of intussusception associated with RRV-TV for the exposure window 3-14 days after the first dose at an age as young as 49 days, the youngest age in the data set at which vaccine was administered; this implies an increased risk of intussusception associated with RRV-TV at all ages studied.

Evaluating the safety of a rotavirus vaccine: the REST of the story

The Rotavirus Efficacy and Safety Trial (REST) was a blinded, placebo-controlled study of the live pentavalent human-bovine vaccine, RotaTeq® (Merck & Co. Inc., West Point, PA). REST was noteworthy because its primary objective was to evaluate the safety of RotaTeq® with regard to intussusception, a rare intestinal illness that occurs with a background incidence of approximately 50 cases per 100 000 infant years. The study involved approximately 70 000 infants at over 500 study sites in 11 countries. The study demonstrated that the risk of intussusception was similar in vaccine and placebo recipients and that the vaccine prevented rotavirus gastroenteritis, ameliorated the severity of disease in those who had any disease, and substantially reduced rotavirus-associated hospitalizations and other health care contacts. This report provides an in-depth review of the background, statistical and regulatory considerations, and execution of REST. We describe the rationale and methods used for sample size, continuous safety monitoring, group sequential design, and detailed study execution. The results of the study have been reported elsewhere. The design and conduct of this study may serve as a useful model for planning other future large-scale clinical trials, especially those evaluating uncommon adverse events.

Efficacy of pentavalent human-bovine (WC3) reassortant rotavirus vaccine based on breastfeeding frequency

The efficacy of a live, oral, pentavalent rotavirus vaccine against G1-4 rotavirus gastroenteritis (RVGE) was retrospectively assessed based on breastfeeding frequency among 5098 infants in a placebo-controlled trial. The efficacy against any RVGE severity for infants never breastfed, sometimes breastfed, or exclusively breastfed was 68.3%, 82.2%, and 68.0%, respectively. The efficacy against severe RVGE was 100%, 95.4%, and 100%, respectively. Breastfeeding did not seem to adversely impact the efficacy of pentavalent rotavirus vaccine.

Varicella immunogenicity with 1- and 2-dose regimens of measles-mumps-rubella-varicella vaccine

A quadrivalent vaccine combining measles, mumps, rubella, and varicella antigens (MMRV) was developed to increase the coverage of varicella vaccine and reduce the number of injections children receive. Although the varicella antigen is as immunogenic in the latest formulation of MMRV vaccine as when it is administered alone, up to 14% of vaccine recipients do not achieve protective levels of anti-varicella antibodies after a single dose, which can result in breakthrough varicella. A second dose of varicella vaccine raises response rates to 99% and was recently recommended by the Advisory Committee on Immunization Practices. Giving the second dose 3 months after the first (at approximately 15 months of age) would provide more protection against varicella but would necessitate a change in the childhood vaccination schedule, which currently calls for a second dose of MMRV vaccine between the ages of 4 and 6 years.

Administration of hepatitis A vaccine at 6 and 12 months of age concomitantly with hexavalent (DTaP-IPV-PRP approximately T-HBs) combination vaccine

BACKGROUND

Administration of two doses of hepatitis A (HA) vaccine to children > or = 2 years of age has been shown to be protective. The present study assessed whether HA vaccine can be administered as early as 6 months of age and whether it can be administered concomitantly with a hexavalent (HV) vaccine at this age.

METHODS

In an open label, randomized, parallel group study, the liquid HV vaccine (HEXAVAC) (diphtheria, tetanus, 2-component acellular pertussis, inactivated poliomyelitis vaccine, Haemophilus influenzae type b conjugated to tetanus protein and hepatitis B) was administered at 2, 4, 6, and 12 months of age to all children. HA vaccine (VAQTA) was given at 7 and 13 months in the separate administration group (Group 1) and at 6 and 12 months in the concomitant administration group (Group 2). Serum samples were obtained at 2, 7, 12, and 14 months in Group 1 and at 2, 7, 12, and 13 months in Group 2. The primary immunogenicity outcomes were the seroconversion rates for HA 1 month after the second dose of HA vaccine in initially seronegative subjects, and the seroconversion rates for each HV antigen 1 month after the third dose of the HV vaccine (both at 7 months of age).

RESULTS

HA seropositivity rates 1 month after the second dose were 100% in both groups, regardless of initial serostatus. The responses to each HV antigen 1 month after the third dose were similar in both groups. The vaccines were generally well tolerated in both groups regardless of vaccine(s) administered.

CONCLUSIONS

A schedule of two doses of HA vaccine, 6 months apart beginning at 6 months of age is highly immunogenic and well tolerated when administered alone or concomitantly with HV vaccine at 6 and 12 months of age.

Immunogenicity of Oka/Merck varicella vaccine in children vaccinated at 12-14 months of age versus 15-23 months of age

OBJECTIVE

Recent reports suggest that breakthrough varicella may be more common in children when the Oka/Merck varicella vaccine is given at 12-14 months of age than when it is given at older ages. An analysis of 5 postlicensure clinical trials with this vaccine was conducted to evaluate immune response relative to the age of the vaccine recipient.

METHODS

In 5 clinical trials, 3771 children, 12 through 23 months of age with no history of varicella, received an injection of varicella vaccine. Varicella-zoster virus (VZV) antibody was measured 6 weeks postvaccination by glycoprotein enzyme-linked immunosorbent assay (gpELISA), an assay that correlates with neutralizing antibody. Endpoints evaluated were the response rate (percent of subjects with VZV antibody > or =5 gpELISA units/mL, a titer shown to correlate with protection) and geometric mean titer (GMT) of VZV antibody. Each endpoint was compared across 3 age groups (12-14, 15-17, and 18-23 months of age). Response rates by initial VZV serostatus were evaluated for children vaccinated at 12-14 months of age to assess whether maternal antibody had an impact on the immune response.

RESULTS

The response rates were similar among 12-14, 15-17, and 18-23 month olds (93.8, 90.8, and 93.1%, respectively); GMTs were significantly higher among the 12-14 month olds (15.1, 13.5, and 13.7 gpELISA units/mL, respectively). Among children 12-14 months of age, response rates and GMTs were similar regardless of their prevaccination VZV serostatus.

CONCLUSIONS

Oka/Merck varicella vaccine is highly immunogenic when given to children 12-14 months of age. The immunogenicity profile is similar to that of children 15-17 and 18-23 months of age. The presence of low titers of VZV antibody before vaccination did not influence vaccine response in 12-14 month olds. These results support current recommendations for universal varicella vaccination beginning at 12 months of age.

Comparison of the safety and immunogenicity of a refrigerator-stable versus a frozen formulation of ProQuad (measles, mumps, rubella, and varicella virus vaccine live)

OBJECTIVE

A refrigerator-stable formulation of ProQuad has been developed to expand the utility of ProQuad to areas in which maintenance of a frozen cold chain (-15 degrees C or colder) during storage and transport may not be feasible. The objective of this study was to demonstrate that the immunogenicity and safety profiles of a refrigerator-stable formulation of ProQuad are similar to the recently licensed frozen formulation.

METHODS

In this double-blind, randomized, multicenter study, healthy 12- to 23-month-old children with negative vaccination and clinical histories for measles, mumps, rubella, varicella, and zoster were vaccinated with either the refrigerator-stable formulation of ProQuad (N = 1006) or the frozen formulation of ProQuad (N = 513). Patients were followed for 42 days after vaccination for adverse experiences. Immunogenicity was evaluated 6 weeks after vaccination.

RESULTS

The refrigerator-stable formulation of ProQuad was generally well tolerated. The incidence of adverse experiences was similar between groups. No vaccine-related serious adverse experiences were reported. For both groups, the response rate was > or = 97.7% for measles, mumps, and rubella, and the percentage of patients with a varicella zoster virus antibody titer of > or = 5 U/mL glycoprotein antigen-based enzyme-linked immunosorbent assay after vaccination was > or = 88.8%. The geometric mean titers for all antigens were numerically slightly higher in patients who received the refrigerator-stable formulation.

CONCLUSIONS

The refrigerator-stable formulation of ProQuad is generally well tolerated, highly immunogenic, and noninferior in terms of postvaccination antibody responses. This refrigerator-stable formulation may improve ease of vaccine administration, increase use of the vaccine throughout the world because of its improved storage conditions, and replace the frozen formulation of ProQuad or any dose of M-M-RII and Varivax in routine practice.

Safety, tolerability and immunogenicity of VAQTA given concomitantly versus nonconcomitantly with other pediatric vaccines in healthy 12-month-old children

BACKGROUND

The objective of this study is to assess whether hepatitis A vaccine is immunogenic and well tolerated when administered to 12-month-old children alone or concomitantly with other routinely administered pediatric vaccines.

METHODS

Six hundred seventeen healthy 12-month-old children were randomized to receive dose 1 of hepatitis A vaccine given alone or concomitantly with measles-mumps-rubella vaccine and varicella vaccine and dose 2 of hepatitis A vaccine given alone or concomitantly with diphtheria-tetanus-acellular pertussis vaccine and optionally with oral or inactivated poliovirus vaccine. Participants were followed for clinical adverse experiences and serologic responses to all vaccine antigens. Antibody responses were compared with historical controls for some indices.

RESULTS

The safety profile was generally comparable whether hepatitis A vaccine was administered alone or concomitantly with other vaccines. When administered alone, the hepatitis A seropositivity rate was 98.3% and 100% for dose 1 and dose 2, respectively, and after dose 2 was similar to historical rates and the geometric mean titers were similar between initially seropositive and initially seronegative subjects (6207 and 6810 mIU/mL, respectively). After concomitant administration with hepatitis A vaccine, antibody responses to measles, mumps, rubella, diphtheria, tetanus and filamentous hemagglutinin (98.8%, 99.6%, 100%, 98.6%, 100% and 83.3%, respectively) were similar to historical controls and response to poliovirus was demonstrated, but immune responses to varicella zoster virus (79%) and pertussis toxoid (76%) were inferior to historical controls.

CONCLUSIONS

Hepatitis A vaccine is highly immunogenic and generally well tolerated when administered to healthy children as young as 12 months of age regardless of initial hepatitis A serostatus and can be administered concomitantly with measles-mumps-rubella vaccine and oral or inactivated poliovirus vaccine.

The safety and immunogenicity of a quadrivalent measles, mumps, rubella and varicella vaccine in healthy children: a study of manufacturing consistency and persistence of antibody

BACKGROUND

This clinical trial was conducted to demonstrate that each of 3 consistency lots of a combined measles, mumps, rubella and varicella vaccine (MMRV) would be well tolerated, induce clinically acceptable and similar immune responses to each antigen and induce immune responses similar to measles, mumps and rubella vaccine (MMR) administered concomitantly with varicella vaccine (V). An additional objective was to evaluate the persistence of antibodies 1 year postvaccination.

METHODS

Study participants 12 to 23 months of age received a single injection of either one of 3 consistency lots of MMRV or MMR + V administered at separate injection sites.

RESULTS

A total of 3,928 healthy children were enrolled at study sites in the United States and Canada. Immune responses to measles, mumps, rubella and varicella in children immunized with each of 3 lots of MMRV were similar and the combined response to all 3 lots was comparable to that of the control group. The 1-year antibody persistence rates for measles, mumps, rubella and varicella viruses were each greater than 95% and comparable among the recipients of the 3 consistency lots of MMRV and the control group. All vaccines were generally well tolerated during the 42 days after vaccination and the overall incidence of adverse experiences was comparable between recipients of MMRV and MMR + V. Rates of fever (temperature >or=38.9 degrees C oral equivalent or tactile) were greater in recipients of MMRV than in recipients of MMR + V (39.1% versus 33.1%, P = 0.001). Fevers were transient and there was no difference in the incidence of febrile seizures.

CONCLUSIONS

MMRV was generally well tolerated and had comparable immunogenicity and overall safety profiles to MMR + V administered concomitantly. Long-term persistence of antibodies after receipt of MMRV is expected based on similar antibody titers against all 4 antigens 1 year postvaccination compared with recipients of MMR and V.

A combination measles, mumps, rubella, and varicella vaccine (ProQuad) given to 4- to 6-year-old healthy children vaccinated previously with M-M-RII and Varivax

BACKGROUND

In the United States, children receive primary doses of M-M-RII (Merck & Co, Inc, West Point, PA) and Varivax (Merck & Co, Inc) beginning at 12 months, often at the same health care visit. Currently a second dose of M-M-RII is given to 4- to 6-year-old children, to increase vaccination rates and to reduce the number of individuals without detectable antibodies. A second dose of a varicella-containing vaccine may result in similar benefits.

OBJECTIVES

To demonstrate that ProQuad (measles, mumps, rubella, and varicella virus vaccine live; Merck & Co, Inc) may be given in place of a second dose of M-M-RII or second doses of M-M-RII and Varivax for 4- to 6-year-old children.

METHODS

Four- to 6-year-old children who had been immunized previously with M-M-RII and Varivax were assigned randomly to receive either ProQuad and placebo (N = 399), M-M-RII and placebo (N = 195), or M-M-RII and Varivax (N = 205) and were then monitored for safety and immunogenicity.

RESULTS

ProQuad was generally well tolerated. Similarity (noninferiority) was demonstrated in postvaccination antibody responses to measles, mumps, and rubella between recipients of ProQuad and all recipients of M-M-RII and in responses to varicella between recipients of ProQuad and recipients of Varivax. Postvaccination seropositivity rates for antibodies against all 4 viruses were nearly 100% in all 3 groups. Small fold increases were observed for measles, mumps, and rubella antibody titers. In contrast, substantial boosts in varicella antibody titers were observed among recipients of a second dose of varicella vaccine, administered as ProQuad or Varivax.

CONCLUSIONS

ProQuad may be used in place of a second dose of M-M-RII or second doses of M-M-RII and Varivax for 4- to 6-year-old children.

Dose-response study of a quadrivalent measles, mumps, rubella and varicella vaccine in healthy children

BACKGROUND

A combined measles, mumps, rubella and varicella (MMRV) vaccine would facilitate universal immunization against 4 diseases by decreasing the number of injections and thus enhancing compliance and coverage rates. If a second dose of varicella vaccine were to be recommended, MMRV could be used to administer a routine second dose of M-M-RII with the added advantage of boosting varicella-zoster virus (VZV) antibody titers.

METHODS

Subjects 12-23 months of age received a single injection of 1 of 3 lots of an MMRV vaccine (ProQuad) containing high, middle or low VZV potency, or VARIVAX given concomitantly with M-M-RII. Recipients of MMRV received a second injection of MMRV approximately 90 days later.

RESULTS

We enrolled 1559 subjects in the study. Antibody response rates to VZV 6 weeks after 1 injection of high potency MMRV (88.6%) or 2 injections of MMRV of any varicella potency (99.7-100%) were similar to the response rates after concomitant administration of M-M-RII and VARIVAX (93.1%). The second injection of MMRV boosted VZV antibody titers. Antibody responses to measles, mumps and rubella were >or=98%, similar to the control, after 1 or 2 injections of MMRV. MMRV was generally well-tolerated during the 42 days after vaccination.

CONCLUSIONS

One injection of high potency MMRV resulted in antibody responses to the 4 vaccine components equivalent to those found after concomitant administration of M-M-RII and VARIVAX. A second injection of MMRV resulted in a significant boost in VZV antibody. This boost may translate into enhanced immunogenicity against varicella, which is known to correlate with increased protection.

Evaluation of a quadrivalent measles, mumps, rubella and varicella vaccine in healthy children

BACKGROUND

A quadrivalent measles, mumps, rubella and varicella vaccine would facilitate universal immunization against all 4 diseases, improve compliance and immunization rates and decrease the number of injections given to children and visits to physicians' offices.

OBJECTIVES

To evaluate 1- and 2-dose regimens of a combined measles, mumps, rubella and varicella vaccine (ProQuad, referred to as MMRV) manufactured with a varicella component of increased potency.

METHODS

In this partially blind, multicenter study, 480 healthy 12- to 23-month-old children were randomized to receive either MMRV and placebo or M-M-RII and VARIVAX. Injections were given concomitantly at separate sites. Subjects randomized to receive MMRV and placebo received a second dose of MMRV 90 days later. Subjects were followed for 42 days after each vaccination for adverse experiences. Immunogenicity was evaluated 6 weeks after each vaccination.

RESULTS

Measles-like rash and fever during days 5-12 were more common after the first dose of MMRV (rash, 5.9%; fever, 27.7%) than after M-M-RII and VARIVAX (rash, 1.9%; fever, 18.7%). The incidence of other adverse events were similar between groups. Response rates were >90% to all vaccine components in both groups. Geometric mean titers to measles and mumps were significantly higher after 1 dose of MMRV than after administration of M-M-RII and VARIVAX. The second dose of MMRV elicited slight to moderate increases in measles, mumps and rubella antibody titers and a substantial increase in varicella antibody titer (from 13.0 to 588.1 glycoprotein antigen-based enzyme-linked immunosorbent assay units/mL).

CONCLUSION

A 1- or 2-dose regimen of MMRV is generally well-tolerated when administered to 12- to 23-month-old children and has a safety and immunogenicity profile similar to that of M-M-RII and VARIVAX administered concomitantly.

Safety and immunogenicity of an inactivated hepatitis A vaccine among HIV-infected subjects

BACKGROUND

Hepatitis A is a major health risk for many human immunodeficiency virus (HIV)-infected individuals. Vaccination is a potentially attractive measure to reduce the incidence of hepatitis A among this population, but data on its safety and immunogenicity are incomplete.

METHODS

Ninety HIV-uninfected adults received an inactivated hepatitis A vaccine (VAQTA; Merck), and 90 HIV-infected subjects were randomized, in double-blind fashion, to receive either the vaccine or placebo. The HIV-infected subjects were stratified by CD4 cell count, with 45 subjects having CD4 cell counts of > or =300 cells/mm3 and 45 subjects having CD4 cell counts of <300 cells/mm3. Vaccine was given at weeks 0 and 24 of the study.Results. Seroconversion rates at week 28 of the study were 94% among the HIV-infected subjects and 100% among the HIV-uninfected control subjects. HIV-infected subjects with CD4 cell counts of <300 cells/mm3 had a seroconversion rate of 87%, and HIV-infected subjects with CD4 cell counts of > or =300 cells/mm3 had a seroconversion rate of 100%. The vaccine was generally well tolerated, and no adverse effect on either HIV load or CD4 cell count was found.

CONCLUSION

Hepatitis A vaccine was both immunogenic and safe among HIV-infected subjects.

Vaccination with measles, mumps and rubella vaccine and varicella vaccine: safety, tolerability, immunogenicity, persistence of antibody and duration of protection against varicella in healthy children

BACKGROUND

Administration of M-M-R II (Measles, Mumps and Rubella Virus Vaccine, Live) and VARIVAX [Varicella Virus Vaccine Live (Oka/Merck)] given concomitantly at separate injection sites during the same office visit could increase vaccine compliance by reducing the number of health care visits for immunizations. We compared the safety and immunogenicity of M-M-R II and VARIVAX given concomitantly at separate sites (Group A) with administration of the two vaccines 6 weeks apart (Group B) as well as the persistence of varicella antibody and the duration of protection afforded by varicella vaccine.

METHODS

A total of 603 healthy children, ages 12 months to 6 years, with no history of measles, mumps, rubella, varicella and zoster or vaccination against these diseases, were randomized to either Group A or B and were followed for clinical reactions and serologic responses to all four viral components. Children were enrolled from August through December, 1993. Subjects were followed for 5 years to evaluate persistence of varicella antibody and breakthrough varicella rates. We compared breakthrough rates to expected attack rates in unvaccinated children to produce estimates of vaccine efficacy.

RESULTS

Both vaccine regimens were generally well-tolerated. There were no significant differences between the groups in the rates of fever, injection site reactions or rashes after vaccination. Seroconversion rates and geometric mean titers for measles, mumps and rubella were not significantly different between groups. The varicella seroconversion rate and percentage with glycoprotein-based ELISA titers > or = 5.0 units were similar between the two groups (99.5 and 92.5% vs. 100 and 94.8% for Groups A and B, respectively), but the geometric mean titers were statistically significantly different (13.2 for Group A and 17.9 for Group B). Varicella antibody persistence rates were >98 to 100% during 6 years of follow-up in both groups. Compared with historical rates, varicella vaccine efficacy during 5 years was estimated to be 90.5% (95% confidence interval, 86.2%, 95.0%) and 88.9% (95% confidence interval, 83.7%, 93.7%) in Groups A and B, respectively.

CONCLUSIONS

Administration of M-M-R II and VARIVAX concomitantly at separate injection sites or 6 weeks apart was generally well-tolerated and immunogenic in healthy children 12 months to 6 years of age. VARIVAX administered with M-M-R II induced persistent immunity and long-term protection against breakthrough varicella infection.

Inverse relationship between six week postvaccination varicella antibody response to vaccine and likelihood of long term breakthrough infection

BACKGROUND

We used the large clinical database that supported the development of Oka/ Merck varicella vaccine to study the relationship between the primary varicella antibody response, as determined by gpELISA, an enzyme-linked immunosorbent assay that detects antibodies to varicella-zoster virus (VZV) glycoprotein, and the subsequent risk of postvaccination breakthrough varicella.

METHODS

We vaccinated 1,164 healthy children with a single dose of varicella vaccine containing 2900 to 9000 plaque-forming units/dose. The primary immune response to vaccination was determined by gpELISA 6 weeks after vaccination. Subjects were followed annually for 7 years to ascertain cases of breakthrough varicella.

RESULTS

The estimated vaccine efficacy among children with a 6-week postvaccination antibody titer of > or = 5 gpELISA units was 95.5% (95% confidence interval, 94.2%, 96.8%) compared with 83.5% (95% confidence interval, 76.9%, 89.5%) for subjects with a titer of <5 gpELISA units. Children with a 6-week postvaccination antibody titer of <5 gpELISA units were 3.5 times more likely than those with a titer of > or = 5 gpELISA units to develop breakthrough varicella.

CONCLUSIONS

We identified a 6-week postvaccination antibody titer of > or = 5 gpELISA units as an approximate correlate of protection. In addition we established an accelerated failure time model based on log normal hazard that predicted varicella breakthrough rates based on the distribution of 6-week postvaccination varicella antibody titers.

Effectiveness of hepatitis A vaccine in a former frequently affected community: 9 years' followup after the Monroe field trial of VAQTA

The Kiryas Joel community in Monroe, N.Y. was the site of the first clinical trial which proved the protective efficacy of hepatitis A vaccine. The vaccine used was VAQTA J. Med. Virol (hepatitis A vaccine, inactivated). In the 9 years since the trial ended vaccination of infants reaching 2 years of age has continued along with monitoring for hepatitis A cases. The prevaccine pattern of frequent outbreaks has converted to a sustained pattern of no outbreaks, despite sporadic introduction of hepatitis A into the community in nonvaccinees. Community use of VAQTA in children 2 years of age and older has proven capable of providing long-term prevention of hepatitis A outbreaks in a formerly frequently affected community despite prolonged sporadic introduction of the virus.

An open randomized study of inactivated hepatitis A vaccine administered concomitantly with typhoid fever and yellow fever vaccines

BACKGROUND

Concomitant administration of several vaccines is a common practice when travel clinics prepare persons for international travel. The purpose of the study was to compare the immunogenicity and safety of hepatitis A, typhoid fever, and yellow fever vaccines administered concomitantly with hepatitis A vaccine administered alone and typhoid fever and yellow fever vaccines administered alone.

METHODS

Healthy adults 18 to 55 years of age were randomized to receive either VAQTA, TyphimVi, and YF-VAX on day 0 and VAQTA at week 24 (Group 1); TyphimVi and YF-VAX on day 0 and an optional dose of VAQTA 1 month later (Group 2); or VAQTA at day 0 and week 24 (Group 3).

RESULTS

From March to December 1997, a total of 240 subjects were enrolled, 80 in each treatment group. Most were female and Caucasian, and the mean age was 29.4 years. Four weeks after vaccine dose 1, seroconversion to protective antibody levels against hepatitis A was 95.9% in Group 1 and 100% in Group 3. In Group 1, 93.4% of subjects demonstrated at least a 4-fold rise in neutralizing antibody levels against typhoid, compared with 90% in Group 2. Serum neutralizing antibody against yellow fever developed in 98.6% of subjects in Group 1 compared with 100% in Group 2.

CONCLUSIONS

These findings were consistent with similarity in the immune responses between treatment groups as defined a priori. The adverse experience (AE) profile did not appear to be substantially affected by concomitant administration of all three vaccines. Providing these three vaccines concomitantly can simplify the process of obtaining pretravel prophylaxis and may help ensure that all needed vaccines are administered.