Use of the Pfizer Pentavalent Meningococcal Vaccine Among Persons Aged ≥10 Years: Recommendations of the Advisory Committee on Immunization Practices - United States, 2023

Meningococcal disease is a life-threatening invasive infection caused by Neisseria meningitidis. Two quadrivalent (serogroups A, C, W, and Y) meningococcal conjugate vaccines (MenACWY) (MenACWY-CRM [Menveo, GSK] and MenACWY-TT [MenQuadfi, Sanofi Pasteur]) and two serogroup B meningococcal vaccines (MenB) (MenB-4C [Bexsero, GSK] and MenB-FHbp [Trumenba, Pfizer Inc.]), are licensed and available in the United States and have been recommended by CDC's Advisory Committee on Immunization Practices (ACIP). On October 20, 2023, the Food and Drug Administration approved the use of a pentavalent meningococcal vaccine (MenACWY-TT/MenB-FHbp [Penbraya, Pfizer Inc.]) for prevention of invasive disease caused by N. meningitidis serogroups A, B, C, W, and Y among persons aged 10-25 years. On October 25, 2023, ACIP recommended that MenACWY-TT/MenB-FHbp may be used when both MenACWY and MenB are indicated at the same visit for the following groups: 1) healthy persons aged 16-23 years (routine schedule) when shared clinical decision-making favors administration of MenB vaccine, and 2) persons aged ≥10 years who are at increased risk for meningococcal disease (e.g., because of persistent complement deficiencies, complement inhibitor use, or functional or anatomic asplenia). Different manufacturers' serogroup B-containing vaccines are not interchangeable; therefore, when MenACWY-TT/MenB-FHbp is used, subsequent doses of MenB should be from the same manufacturer (Pfizer Inc.). This report summarizes evidence considered for these recommendations and provides clinical guidance for the use of MenACWY-TT/MenB-FHbp.

Tick-Borne Encephalitis Vaccine: Recommendations of the Advisory Committee on Immunization Practices, United States, 2023

Tick-borne encephalitis (TBE) virus is focally endemic in parts of Europe and Asia. The virus is primarily transmitted to humans by the bites of infected

Ixodes species ticks but can also be acquired less frequently by alimentary transmission. Other rare modes of transmission include through breastfeeding, blood transfusion, solid organ transplantation, and slaughtering of viremic animals. TBE virus can cause acute neurologic disease, which usually results in hospitalization, often permanent neurologic or cognitive sequelae, and sometimes death. TBE virus infection is a risk for certain travelers and for laboratory workers who work with the virus. In August 2021, the Food and Drug Administration approved Ticovac TBE vaccine for use among persons aged ≥1 year. This report summarizes the epidemiology of and risks for infection with TBE virus, provides information on the immunogenicity and safety of TBE vaccine, and summarizes the recommendations of the Advisory Committee on Immunization Practices (ACIP) for use of TBE vaccine among U.S. travelers and laboratory workers.

The risk for TBE for most U.S. travelers to areas where the disease is endemic is very low. The risk for exposure to infected ticks is highest for persons who are in areas where TBE is endemic during the main TBE virus transmission season of April–November and who are planning to engage in recreational activities in woodland habitats or who might be occupationally exposed. All persons who travel to areas where TBE is endemic should be advised to take precautions to avoid tick bites and to avoid the consumption of unpasteurized dairy products because alimentary transmission of TBE virus can occur. TBE vaccine can further reduce infection risk and might be indicated for certain persons who are at higher risk for TBE. The key factors in the risk-benefit assessment for vaccination are likelihood of exposure to ticks based on activities and itinerary (e.g., location, rurality, season, and duration of travel or residence). Other risk-benefit considerations should include 1) the rare occurrence of TBE but its potentially high morbidity and mortality, 2) the higher risk for severe disease among certain persons (e.g., older persons aged ≥60 years), 3) the availability of an effective vaccine, 4) the possibility but low probability of serious adverse events after vaccination, 5) the likelihood of future travel to areas where TBE is endemic, and 6) personal perception and tolerance of risk

ACIP recommends TBE vaccine for U.S. persons who are moving or traveling to an area where the disease is endemic and will have extensive exposure to ticks based on their planned outdoor activities and itinerary. Extensive exposure can be considered based on the duration of travel and frequency of exposure and might include shorter-term (e.g., <1 month) travelers with daily or frequent exposure or longer-term travelers with regular (e.g., a few times a month) exposure to environments that might harbor infected ticks. In addition, TBE vaccine may be considered for persons who might engage in outdoor activities in areas where ticks are likely to be found, with a decision to vaccinate made on the basis of an assessment of their planned activities and itinerary, risk factors for a poor medical outcome, and personal perception and tolerance of risk. In the laboratory setting, ACIP recommends TBE vaccine for laboratory workers with a potential for exposure to TBE virus

The Present and Future of the Adult Pneumococcal Vaccine Program in the United States

Adult Pneumococcal Vaccine Program in the United StatesStreptococcus pneumoniae (pneumococcus) is a common cause of bacterial respiratory infections leading to substantial morbidity and mortality. Here, Kobayashi et al. discuss the recently updated U.S. guidelines for adult pneumococcal vaccination.

Pneumococcal Vaccine for Adults Aged ≥19 Years: Recommendations of the Advisory Committee on Immunization Practices, United States, 2023

This report compiles and summarizes all published recommendations from CDC’s Advisory Committee on Immunization Practices (ACIP) for use of pneumococcal vaccines in adults aged ≥19 years in the United States. This report also includes updated and new clinical guidance for implementation from CDC

Before 2021, ACIP recommended 23-valent pneumococcal polysaccharide vaccine (PPSV23) alone (up to 2 doses), or both a single dose of 13-valent pneumococcal conjugate vaccine (PCV13) in combination with 1–3 doses of PPSV23 in series (PCV13 followed by PPSV23), for use in U.S. adults depending on age and underlying risk for pneumococcal disease. In 2021, two new pneumococcal conjugate vaccines (PCVs), a 15-valent and a 20-valent PCV (PCV15 and PCV20), were licensed for use in U.S. adults aged ≥18 years by the Food and Drug Administration

ACIP recommendations specify the use of either PCV20 alone or PCV15 in series with PPSV23 for all adults aged ≥65 years and for adults aged 19–64 years with certain underlying medical conditions or other risk factors who have not received a PCV or whose vaccination history is unknown. In addition, ACIP recommends use of either a single dose of PCV20 or ≥1 dose of PPSV23 for adults who have started their pneumococcal vaccine series with PCV13 but have not received all recommended PPSV23 doses. Shared clinical decision-making is recommended regarding use of a supplemental PCV20 dose for adults aged ≥65 years who have completed their recommended vaccine series with both PCV13 and PPSV23

Updated and new clinical guidance for implementation from CDC includes the recommendation for use of PCV15 or PCV20 for adults who have received PPSV23 but have not received any PCV dose. The report also includes clinical guidance for adults who have received 7-valent PCV (PCV7) only and adults who are hematopoietic stem cell transplant recipients

Associations Between Weight and Lower Respiratory Tract Disease Outcomes in Hospitalized Children

OBJECTIVE

To identify associations between weight status and clinical outcomes in children with lower respiratory tract infection (LRTI) or asthma requiring hospitalization.

METHODS

We performed a retrospective cohort study of 2 to 17 year old children hospitalized for LRTI and/or asthma from 2009 to 2019 using electronic health record data from the PEDSnet clinical research network. Children <2 years, those with medical complexity, and those without a calculable BMI were excluded. Children were classified as having underweight, normal weight, overweight, or class 1, 2, or 3 obesity based on Body Mass Index percentile for age and sex. Primary outcomes were need for positive pressure respiratory support and ICU admission. Subgroup analyses were performed for children with a primary diagnosis of asthma. Outcomes were modeled with mixed-effects multivariable logistic regression incorporating age, sex, and payer as fixed effects.

RESULTS

We identified 65 132 hospitalizations; 6.7% with underweight, 57.8% normal weight, 14.6% overweight, 13.2% class 1 obesity, 5.0% class 2 obesity, and 2.8% class 3 obesity. Overweight and obesity were associated with positive pressure respiratory support (class 3 obesity versus normal weight odds ratio [OR] 1.62 [1.38-1.89]) and ICU admission (class 3 obesity versus normal weight OR 1.26 [1.12-1.42]), with significant associations for all categories of overweight and obesity. Underweight was also associated with positive pressure respiratory support (OR 1.39 [1.24-1.56]) and ICU admission (1.40 [1.30-1.52]).

CONCLUSIONS

Both underweight and overweight or obesity are associated with increased severity of LRTI or asthma in hospitalized children.

Dengue: A Growing Problem With New Interventions

Dengue is the disease caused by 1 of 4 distinct, but closely related dengue viruses (DENV-1-4) that are transmitted by Aedes spp. mosquito vectors. It is the most common arboviral disease worldwide, with the greatest burden in tropical and sub-tropical regions. In the absence of effective prevention and control measures, dengue is projected to increase in both disease burden and geographic range. Given its increasing importance as an etiology of fever in the returning traveler or the possibility of local transmission in regions in the United States with competent vectors, as well as the risk for large outbreaks in endemic US territories and associated states, clinicians should understand its clinical presentation and be familiar with appropriate testing, triage, and management of patients with dengue. Control and prevention efforts reached a milestone in June 2021 when the Advisory Committee on Immunization Practices (ACIP) recommended Dengvaxia for routine use in children aged 9 to 16 years living in endemic areas with laboratory confirmation of previous dengue virus infection. Dengvaxia is the first vaccine against dengue to be recommended for use in the United States and one of the first to require laboratory testing of potential recipients to be eligible for vaccination. In this review, we outline dengue pathogenesis, epidemiology, and key clinical features for front-line clinicians evaluating patients presenting with dengue. We also provide a summary of Dengvaxia efficacy, safety, and considerations for use as well as an overview of other potential new tools to control and prevent the growing threat of dengue .

Use of 15-Valent Pneumococcal Conjugate Vaccine and 20-Valent Pneumococcal Conjugate Vaccine Among U.S. Adults: Updated Recommendations of the Advisory Committee on Immunization Practices - United States, 2022

In 2021, 20-valent pneumococcal conjugate vaccine (PCV) (PCV20) (Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc.) and 15-valent PCV (PCV15) (Merck Sharp & Dohme Corp.) were licensed by the Food and Drug Administration for adults aged ≥18 years, based on studies that compared antibody responses to PCV20 and PCV15 with those to 13-valent PCV (PCV13) (Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc.). Antibody responses to two additional serotypes included in PCV15 were compared to corresponding responses after PCV13 vaccination, and antibody responses to seven additional serotypes included in PCV20 were compared with those to the 23-valent pneumococcal polysaccharide vaccine (PPSV23) (Merck Sharp & Dohme Corp.). On October 20, 2021, the Advisory Committee on Immunization Practices (ACIP) recommended use of either PCV20 alone or PCV15 in series with PPSV23 for all adults aged ≥65 years, and for adults aged 19-64 years with certain underlying medical conditions or other risk factors* who have not previously received a PCV or whose previous vaccination history is unknown. ACIP employed the Evidence to Recommendation (EtR) framework,^† using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE)^§ approach to guide its deliberations regarding use of these vaccines. Before this, PCV13 and PPSV23 were recommended for use for U.S. adults and the recommendations varied by age and risk groups. This was simplified in the new recommendations.

Dengue Vaccine: Recommendations of the Advisory Committee on Immunization Practices, United States, 2021

Dengue is a vectorborne infectious disease caused by dengue viruses (DENVs), which are predominantly transmitted by Aedes aegypti and Aedes albopictus mosquitos. Dengue is caused by four closely related viruses (DENV-1–4), and a person can be infected with each serotype for a total of four infections during their lifetime. Areas where dengue is endemic in the United States and its territories and freely associated states include Puerto Rico, American Samoa, the U.S. Virgin Islands, the Federated States of Micronesia, the Republic of Marshall Islands, and the Republic of Palau. This report summarizes the recommendations of the Advisory Committee on Immunization Practices (ACIP) for use of the Dengvaxia vaccine in the United States. The vaccine is a live-attenuated, chimeric tetravalent dengue vaccine built on a yellow fever 17D backbone. Dengvaxia is safe and effective in reducing dengue-related hospitalizations and severe dengue among persons who have had dengue infection in the past. Previous natural infection is important because Dengvaxia is associated with an increased risk for severe dengue in those who experience their first natural infection (i.e., primary infection) after vaccination. Dengvaxia was licensed by the Food and Drug Administration for use among children and adolescents aged 9–16 years (referred to in this report as children). ACIP recommends vaccination with Dengvaxia for children aged 9–16 having evidence of a previous dengue infection and living in areas where dengue is endemic. Evidence of previous dengue infection, such as detection of anti-DENV immunoglobulin G with a highly specific serodiagnostic test, will be required for eligible children before vaccination.

Weight Status and Risk of Inpatient Admission for Children With Lower Respiratory Tract Disease

OBJECTIVES

To identify associations between weight category and hospital admission for lower respiratory tract disease (LRTD), defined as asthma, community-acquired pneumonia, viral pneumonia, or bronchiolitis, among children evaluated in pediatric emergency departments (PEDs).

METHODS

We performed a retrospective cohort study of children 2 to <18 years of age evaluated in the PED at 6 children's hospitals within the PEDSnet clinical research network from 2009 to 2019. BMI percentile of children was classified as underweight, healthy weight, overweight, and class 1, 2, or 3 obesity. Children with complex chronic conditions were excluded. Mixed-effects multivariable logistic regression was used to assess associations between BMI categories and hospitalization or 7- and 30-day PED revisits, adjusted for covariates (age, sex, race and ethnicity, and payer).

RESULTS

Among 107 446 children with 218 180 PED evaluations for LRTD, 4.5% had underweight, 56.4% had healthy normal weight, 16.1% had overweight, 14.6% had class 1 obesity, 5.5% had class 2 obesity, and 3.0% had class 3 obesity. Underweight was associated with increased risk of hospital admission compared with normal weight (odds ratio [OR] 1.76; 95% confidence interval [CI] 1.69-1.84). Overweight (OR 0.87; 95% CI 0.85-0.90), class 1 obesity (OR 0.88; 95% CI 0.85-0.91), and class 2 obesity (OR 0.91; 95% CI 0.87-0.96) had negative associations with hospital admission. Class 1 and class 2, but not class 3, obesity had small positive associations with 7- and 30-day PED revisits.

CONCLUSIONS

We found an inverse relationship between patient weight category and risk for hospital admission in children evaluated in the PED for LRTD.

Suboptimal uptake of human papillomavirus (HPV) vaccine in survivors of childhood and adolescent and young adult (AYA) cancer

PURPOSE

To estimate the population-based incidence of HPV vaccination after childhood cancer.

METHODS

Pediatric and young adult cancer survivors identified in the institutional Comprehensive Cancer Center registry were linked to the North Carolina Immunization Registry (NCIR). Initiation and completion of any HPV vaccine was evaluated in survivors born between 1984 and 2002 with an NCIR record by December 2014. Descriptive statistics and Kaplan-Meier estimates of cumulative incidence were stratified by sex and age at eligibility for vaccine. Cox proportional hazards were conducted and stratified by sex.

RESULTS

Among 879 (n = 428 female; n = 451 male) study-eligible cancer survivors without prior HPV vaccination (n = 501 < 18 years, n = 378 ≥ 18 years at the time of eligibility), the cumulative incidence of HPV vaccine initiation following cancer therapy was 48.1% among females at 8.2 years and 29.2% among males at 5.0 years after vaccine eligibility among those < 18 years, and 6.2% among females at 8.1 years and 2.0% among males at 4.2 years after vaccine eligibility among those ≥ 18 years. Among those who initiated vaccination, 53% of females and 43% of males completed a 3-dose series. Younger age at cancer diagnosis (≤ 10 and 11-14 years vs. ≥ 15 years) and shorter interval from diagnosis to vaccine eligibility were more likely to initiate vaccination in models adjusted for age at eligibility, race/ethnicity, cancer type, relapse, and transplant.

CONCLUSIONS

Despite the benefit of a cancer prevention strategy, cancer survivors are sub-optimally vaccinated against HPV.

IMPLICATIONS FOR CANCER SURVIVORS

Immunization registries can help oncologists and primary care providers identify gaps in vaccination and target HPV vaccine delivery in survivors.

Association of Prior Vaccination With Influenza Vaccine Effectiveness in Children Receiving Live Attenuated or Inactivated Vaccine

IMPORTANCE

Some studies have reported negative effects of prior-season influenza vaccination. Prior-season influenza vaccination effects on vaccine effectiveness (VE) in children are not well understood.

OBJECTIVE

To assess the association of prior-season influenza vaccination with subsequent VE in children aged 2 to 17 years.

DESIGN, SETTING, AND PARTICIPANTS

This multiseason, test-negative case-control study was conducted in outpatient clinics at 4 US sites among children aged 2 to 17 years with a medically attended febrile acute respiratory illness. Participants were recruited during the 2013-2014, 2014-2015, and 2015-2016 seasons when influenza circulated locally. Cases were children with influenza confirmed by reverse-transcription polymerase chain reaction. Test-negative control individuals were children with negative test results for influenza.

EXPOSURES

Vaccination history, including influenza vaccine type received in the enrollment season (live attenuated influenza vaccine [LAIV], inactivated influenza vaccine [IIV], or no vaccine) and season before enrollment (LAIV, IIV, or no vaccine), determined from medical records and immunization registries.

MAIN OUTCOMES AND MEASURES

LAIV and IIV effectiveness by influenza type and subtype (influenza A[H1N1]pdm09, influenza A[H3N2], or influenza B), estimated as 100 × (1 - odds ratio) in a logistic regression model with adjustment for potential confounders. Prior season vaccination associations were assessed with an interaction term.

RESULTS

Of 3369 children (1749 [52%] male; median age, 6.6 years [range, 2-17 years]) included in the analysis, 772 (23%) had a positive test result for influenza and 1674 (50%) were vaccinated in the enrollment season. Among LAIV recipients, VE against influenza A(H3N2) was higher among children vaccinated in both the enrollment and 1 prior season (50.3% [95% CI, 17.0% to 70.2%]) than among those without 1 prior season vaccination (-82.4% [95% CI, -267.5% to 9.5%], interaction P < .001). The effectiveness of LAIV against influenza A(H1N1)pdm09 was not associated with prior season vaccination among those with prior season vaccination (47.5% [95% CI, 11.4% to 68.9%]) and among those without prior season vaccination (7.8% [95% CI, -101.9% to 57.9%]) (interaction P = .37). Prior season vaccination was not associated with effectiveness of IIV against influenza A(H3N2) (38.7% [95% CI, 6.8% to 59.6%] among those with prior-season vaccination and 23.2% [95% CI, -38.3% to 57.4%] among those without prior-season vaccination, interaction P = .16) or with effectiveness of IIV against influenza A[H1N1]pdm09 (72.4% [95% CI, 56.0% to 82.7%] among those with prior season vaccination and 67.5% [95% CI, 32.1% to 84.4%] among those without prior season vaccination, interaction P = .93). Residual protection from prior season vaccination only (no vaccination in the enrollment season) was observed for influenza B (LAIV: 60.0% [95% CI, 36.8% to 74.7%]; IIV: 60.0% [36.9% to 74.6%]). Similar results were observed in analyses that included repeated vaccination in 2 and 3 prior seasons.

CONCLUSIONS AND RELEVANCE

Influenza VE varied by influenza type and subtype and vaccine type, but prior-season vaccination was not associated with reduced VE. These findings support current recommendations for annual influenza vaccination of children.

2015-2016 Vaccine Effectiveness of Live Attenuated and Inactivated Influenza Vaccines in Children in the United States

Background

In the 2015-2016 season, quadrivalent live attenuated influenza vaccine (LAIV) and both trivalent and quadrivalent inactivated influenza vaccine (IIV) were available in the United States.

Methods

This study, conducted according to a test-negative case-control design, enrolled children aged 2-17 years presenting to outpatient settings with fever and respiratory symptoms for <5 days at 8 sites across the United States between 30 November 2015 and 15 April 2016. A nasal swab was obtained for reverse-transcriptase polymerase chain reaction (RT-PCR) testing for influenza, and influenza vaccination was verified in the medical record or vaccine registry. Influenza vaccine effectiveness (VE) was estimated using a logistic regression model.

Results

Of 1012 children retained for analysis, most children (59%) were unvaccinated, 10% received LAIV, and 31% received IIV. Influenza A (predominantly antigenically similar to the A/California/7/2009 strain) was detected in 14% and influenza B (predominantly a B/Victoria lineage) in 10%. For all influenza, VE was 46% (95% confidence interval [CI], 7%-69%) for LAIV and 65% (48%-76%) for IIV. VE against influenza A(H1N1)pdm09 was 50% (95% CI, -2% to 75%) for LAIV and 71% (51%-82%) for IIV. The odds ratio for vaccine failure with RT-PCR-confirmed A(H1N1)pdm09 was 1.71 (95% CI, 0.78-3.73) in LAIV versus IIV recipients.

Conclusions

LAIV and IIV demonstrated effectiveness against any influenza among children aged 2-17 years in 2015-2016. When compared to all unvaccinated children, VE against influenza A(H1N1)pdm09 was significant for IIV but not LAIV.

Clinical Trials Registration

NCT01997450.

Impact of Prior Vaccination History on Risk of Vaccine Failure with Live Attenuated and Inactivated Influenza Vaccines in Children, 2013–14 through 2015–16

Background

Prior season vaccination may influence influenza vaccine effectiveness; however, little is known about the impact of prior vaccination or vaccine type received. We assessed prior vaccination history and risk of influenza in children over 3 seasons.

Methods

Children aged 2–17 years seeking outpatient care for febrile acute respiratory illness were recruited during the 2013–14 through 2015–16 seasons (1 vaccine-mismatched H3N2 season and 2 H1N1pdm09 seasons) at 4 US sites. Influenza was confirmed by RT-PCR. Vaccination data for the season of enrollment (current) and 3 prior seasons were obtained from medical records and immunization registries. Among children who received 1 dose of influenza vaccine during the current season, risk of vaccine failure (ie, PCR-confirmed influenza) was estimated using test-negative design with logistic regression models adjusted for age, season, enrollment site, enrollment week (relative to peak), and outpatient visits. Risk of failure with live attenuated influenza vaccine (LAIV) and inactivated influenza vaccine (IIV) were modeled separately. Separate models were used for vaccine history based on number of seasons and vaccine type received (ie, none, LAIV, IIV, both).

Results

Influenza was detected in 191 (12%) of 1601 children who received 1 vaccine dose during the current season: 117 H3N2 and 74 H1N1pdm09. Among 508 current season LAIV recipients, 239 (47%) received LAIV and 144 (28%) received IIV in the prior season. Among 1093 current season IIV recipients, 94 (9%) received LAIV and 711 (65%) received IIV in the prior season. For LAIV, receipt of vaccine (any type) in a prior season was associated with a decreased risk of H3N2 failure (odds ratio 0.23; 95% CI, 0.09–0.57). Prior vaccination was not associated with risk of LAIV vaccine failure against H1N1pdm09. For IIV, there was no evidence that prior vaccination was associated with risk of vaccine failure against H3N2 or H1N1pdm09. Similar results were seen in children without any high-risk conditions.

Conclusion

Risk of vaccine failure among vaccinated children varied by vaccine type and virus subtype. Future studies should examine immunologic effects to better understand these differences.

Disclosures

H. Q. McLean, MedImmune: Grant Investigator, Research support; H. Caspard, MedImmune: Employee, Salary; M. R. Griffin, MedImmune: Grant Investigator, Grant recipient; M. Gaglani, MedImmune: Investigator, Research support; T. R. Peters, MedImmune: Investigator, Research support; K. A. Poehling, MedImmune: Investigator, Research support; C. S. Ambrose, AstraZeneca: Employee, Salary; E. Belongia, MedImmune: Grant Investigator, Research support

Effectiveness of live attenuated influenza vaccine and inactivated influenza vaccine in children during the 2014-2015 season

BACKGROUND

A clinical study found that live attenuated influenza vaccine (LAIV) was superior to inactivated influenza vaccine (IIV) against drifted A(H3N2) viruses in children. During the 2014-2015 influenza season, widespread circulation of antigenically and genetically drifted A(H3N2) viruses provided an opportunity to evaluate subtype-specific vaccine effectiveness (VE) of quadrivalent LAIV (LAIV4) and IIV in children.

METHODS

Children (2-17years) with febrile acute respiratory illness <5days' duration were enrolled at 4 outpatient sites in the United States during the 2014-2015 influenza season. Nasal swabs were tested for influenza by reverse transcription polymerase chain reaction; vaccination dates were obtained from medical records or immunization registries. VE was estimated using a test-negative design comparing odds of vaccination among influenza cases and test-negative controls with adjustment for potential confounders.

RESULTS

Among 1696 children enrolled, 1511 (89%) were included in the analysis. Influenza was detected in 427 (28%) children; 317 had influenza A(H3N2) and 110 had influenza B. Most influenza isolates were characterized as a drifted strain of influenza A(H3N2) or a drifted strain of B/Yamagata. For LAIV4, adjusted VE was 50% (95% confidence interval [CI], 27-66%) against any influenza, 30% (95% CI, -6% to 54%) against influenza A(H3N2), and 87% (95% CI, 63-96%) against type B. For IIV, adjusted VE was 39% (95% CI, 18-54%) against any influenza, 40% (95% CI, 16-58%) against A(H3N2), and 29% (95% CI, -15% to 56%) against type B. Odds of influenza for LAIV4 versus IIV recipients were similar against influenza A(H3N2) (odds ratio [OR], 1.17; 95% CI, 0.73-1.86) and lower against influenza B (OR, 0.18; 95% CI, 0.06-0.55).

CONCLUSIONS

LAIV4 and IIV provided similar protection against a new antigenic variant A(H3N2). LAIV4 provided significantly greater protection than IIV against a drifted influenza B strain. ClinicalTrials.gov identifier: NCT01997450.

Estimating the Burden of Pandemic Infectious Disease: The Case of the Second Wave of Pandemic Influenza H1N1 in Forsyth County, North Carolina

BACKGROUND

Understanding the burden of influenza A(H1N1)pdm09 virus during the second wave of 2009-2010 is important for future pandemic planning.

METHODS

Persons who presented to the emergency department (ED) or were hospitalized with fever and/or acute respiratory symptoms at the academic medical center in Forsyth County, North Carolina were prospectively enrolled and underwent nasal/throat swab testing for influenza A(H1N1)pdm09. Laboratory-confirmed cases of influenza A(H1N1)pdm09 virus identified through active surveillance were compared by capture-recapture analysis to those identified through independent, passive surveillance (physician-ordered influenza testing). This approach estimated the number of total cases, including those not captured by either surveillance method. A second analysis estimated the total number of influenza A(H1N1)pdm09 cases by multiplying weekly influenza percentages determined via active surveillance by weekly counts of influenza-associated discharge diagnoses from administrative data. Market share adjustments were used to estimate influenza A(H1N1)pdm09 virus ED visits or hospitalizations per 1,000 residents.

RESULTS

Capture-recapture analysis estimated that 753 residents (95% confidence interval [CI], 424-2,735) with influenza A(H1N1)pdm09 virus were seen in the academic medical center from September 2009 through mid-April 2010; this result yielded an estimated 4.7 (95% CI, 2.6-16.9) influenza A(H1N1)pdm09 virus ED visits or hospitalizations per 1,000 residents. Similarly, 708 visits were estimated using weekly influenza percentages and influenza-associated discharge diagnoses, yielding an estimated 4.4 influenza A(H1N1)pdm09 virus ED visits or hospitalizations per 1,000 residents.

CONCLUSION

This study demonstrates that the burden of influenza A(H1N1)pdm09 virus in ED and inpatient settings by capture-recapture analysis was 4-5 per 1,000 residents; this rate was approximately 8-fold higher than that detected by physician-ordered influenza testing.

Effectiveness of live attenuated influenza vaccine and inactivated influenza vaccine in children 2-17 years of age in 2013-2014 in the United States

BACKGROUND

A postmarketing observational study was initiated to evaluate quadrivalent live attenuated influenza vaccine (LAIV) effectiveness in children aged 2-17 years in the United States.

METHODS

Children and adolescents aged 2-17 years seeking outpatient care for febrile acute respiratory illness <5 days duration were enrolled at 4 geographically diverse sites during the 2013-2014 influenza season. Nasal swabs were tested for influenza using reverse transcription polymerase chain reaction. Vaccination status was documented from medical records or immunization registries. Children who received ≥1 dose of influenza vaccine ≥14 days before study visit were considered vaccinated. Vaccine effectiveness (VE) was estimated as 100×(1-adjusted odds ratio), where the odds of interest are the odds of vaccine exposure among influenza cases and test-negative controls.

RESULTS

In total, 1033 children and adolescents were included in the analysis. Influenza was detected in 14% (145/1033) of all children, with 74% (108/145) of the influenza cases due to A/H1N1pdm09 strains, 21% (31) to influenza B, and 4% (6) to influenza H3N2. LAIV did not show significant effectiveness against A/H1N1pdm09 (VE 13% [95% CI: -55 to 51]) but was effective against B/Yamagata strains (82% [95% CI: 12-96]). Inactivated influenza vaccine was effective against A/H1N1pdm09 (74% [95% CI: 50-86]) and B/Yamagata (70% [95% CI: 18-89]).

CONCLUSIONS

LAIV provided significant protection against B/Yamagata influenza but not against A/H1N1pdm09 in children aged 2-17 years in 2013-2014, resulting in a proposed change of the 2015-2016 formulation with a new and more heat-stable A/H1N1pdm09 LAIV strain.

Predictors of Influenza Diagnosis Among Patients With Laboratory-Confirmed Influenza

OBJECTIVE

This study was performed to determine predictors of clinical influenza diagnosis among patients with laboratory-confirmed influenza.

METHODS

Prospective, laboratory-confirmed surveillance for influenza was conducted among patients of all ages who were hospitalized or presented to the emergency department with fever and respiratory symptoms during 2009-2013. We evaluated all enrolled persons who had influenza confirmed by viral culture and/or polymerase chain reaction and received any discharge diagnosis. The primary outcome, clinical influenza diagnosis, was defined as (1) a discharge diagnosis of influenza, (2) a prescription of neuraminidase inhibitor, or (3) a rapid test positive for influenza virus. Bivariate analyses and multiple logistic regression modeling were performed.

RESULTS

Influenza was diagnosed for 29% of 504 enrolled patients with laboratory-confirmed influenza and for 56% of 236 patients with high-risk conditions. Overall, clinical influenza diagnosis was predicted by race/ethnicity, insurance status, year, being hospitalized, having high-risk conditions, and receiving no diagnosis of bacterial infection. Being diagnosed with a bacterial infection reduced the odds of receiving an influenza diagnosis by >3-fold for all patients and for patients with high-risk conditions.

CONCLUSIONS

Many influenza virus-positive patients, including those with high-risk conditions, do not receive a clinical diagnosis of influenza. The pattern of clinical diagnoses among influenza virus-positive patients suggests preferential consideration of bacterial diseases as a diagnosis.

Influenza-related hospitalization and ED visits in children less than 5 years: 2000-2011

BACKGROUND AND OBJECTIVES

In the United States, recommendations for annual influenza vaccination gradually expanded from 2004 to 2008, to include all children aged ≥6 months. The effects of these policies on vaccine uptake and influenza-associated health care encounters are unclear. The objectives of the study were to examine the annual incidence of influenza-related health care encounters and vaccine uptake among children age 6 to 59 months from 2000-2001 through 2010-2011 in Davidson County, TN.

METHODS

We estimated the proportion of laboratory-confirmed influenza-related hospitalizations and emergency department (ED) visits by enrolling and testing children with acute respiratory illness or fever. We estimated influenza-related health care encounters by multiplying these proportions by the number of acute respiratory illness/fever hospitalizations and ED visits for county residents. We assessed temporal trends in vaccination coverage, and influenza-associated hospitalizations and ED visit rates.

RESULTS

The proportion of fully vaccinated children increased from 6% in 2000-2001 to 38% in 2010-2011 (P < .05). Influenza-related hospitalizations ranged from 1.9 to 16.0 per 10 000 children (median 4.5) per year. Influenza-related ED visits ranged from 89 to 620 per 10 000 children (median 143) per year. Significant decreases in hospitalizations (P < .05) and increases in ED visits (P < .05) over time were not clearly related to vaccination trends. Influenza-related encounters were greater when influenza A(H3N2) circulated than during other years with median rates of 8.2 vs 3.2 hospitalizations and 307 vs 143 ED visits per 10 000 children, respectively.

CONCLUSIONS

Influenza vaccination increased over time; however, the proportion of fully vaccinated children remained <50%. Influenza was associated with a substantial illness burden particularly when influenza A(H3N2) predominated.

Relative timing of influenza disease by age group

A detailed understanding of influenza movement in communities during yearly epidemics is needed to inform improved influenza control programs. We sought to determine the relative timing of influenza presentation and symptom onset by age group and influenza strain. Prospective, laboratory-confirmed surveillance was performed over three moderate influenza seasons in emergency departments and inpatient settings of both medical centers in Winston-Salem, NC. Influenza disease presented first in school age children through community epidemics of influenza A(H1N1)pdm09 and influenza B, and first in persons 5-49 years old for influenza A(H3N2). This finding indicates that influenza prevention in persons 5-49 years of age may be particularly important in influenza epidemic control.

Respiratory syncytial virus-associated hospitalizations among children less than 24 months of age

BACKGROUND

Respiratory syncytial virus (RSV) infection is a leading cause of hospitalization among infants. However, estimates of the RSV hospitalization burden have varied, and precision has been limited by the use of age strata grouped in blocks of 6 to ≥ 12 months.

METHODS

We analyzed data from a 5-year, prospective, population-based surveillance for young children who were hospitalized with laboratory-confirmed (reverse-transcriptase polymerase chain reaction) RSV acute respiratory illness (ARI) during October through March 2000-2005. The total population at risk was stratified by month of age by birth certificate information to yield hospitalization rates.

RESULTS

There were 559 (26%) RSV-infected children among the 2149 enrolled children hospitalized with ARI (85% of all eligible children with ARI). The average RSV hospitalization rate was 5.2 per 1000 children <24 months old. The highest age-specific rate was in infants 1 month old (25.9 per 1000 children). Infants ≤ 2 months of age, who comprised 44% of RSV-hospitalized children, had a hospitalization rate of 17.9 per 1000 children. Most children (79%) were previously healthy. Very preterm infants (<30 weeks' gestation) accounted for only 3% of RSV cases but had RSV hospitalization rates 3 times that of term infants.

CONCLUSIONS

Young infants, especially those who were 1 month old, were at greatest risk of RSV hospitalization. Four-fifths of RSV-hospitalized infants were previously healthy. To substantially reduce the burden of RSV hospitalizations, effective general preventive strategies will be required for all young infants, not just those with risk factors.

Influenza testing, diagnosis, and treatment in the emergency department in 2009-2010 and 2010-2011

OBJECTIVES

The objective was to describe patterns of rapid influenza test ordering, diagnosis of influenza, and antiviral prescribing by the treating physician for children and adults presenting to emergency departments (EDs) with fever and acute respiratory symptoms in Winston-Salem, North Carolina, over two influenza seasons.

METHODS

The authors prospectively enrolled patients presenting to the ED with fever and acute respiratory symptoms for two influenza seasons: H1N1 pandemic of September 2009 through mid-May 2010 and November 2010 through April 2011. Enrolled patients had nose or and throat swabs obtained and tested for influenza by viral culture and polymerase chain reaction (PCR) testing. Demographic information and medical history were obtained by patient or guardian report. Testing, treatment, and discharge diagnosis from the ED visit, as well as medical history and insurance status, were ascertained from chart review.

RESULTS

Among 2,293 eligible patients approached, 1,657 (72%) were enrolled, of whom 38% were younger than 18 years, 47% were 18 to 49 years, and 15% were 50 years of age and older. Overall, 14% had culture- or PCR-confirmed influenza. The odds of 1) rapid influenza test ordering, 2) a physician diagnosis of influenza, and 3) prescribing antiviral treatment during the ED visit were fourfold higher among patients with than without culture- or PCR-confirmed influenza. The odds of rapid influenza test ordering were threefold lower in 2009/2010 than 2010/2011, whereas the odds of physician diagnosis of influenza and antiviral prescriptions were 2- and 3.5-fold higher, respectively.

CONCLUSIONS

In 2009/2010 compared to 2010/2011, the odds of rapid influenza test ordering were lower, whereas the odds of influenza-specific discharge diagnoses and antiviral prescriptions were higher among patients presenting to the ED with culture/PCR-confirmed influenza. These results demonstrated a gap between clinical practice and recommendations for the diagnosis and treatment of influenza from the Centers for Disease Control and Prevention (CDC).

Verifying influenza and pneumococcal immunization status of children in 2009-2010 from primary care practice records and from the North Carolina Immunization Registry

BACKGROUND

The North Carolina Immunization Registry (NCIR) has been available since 2004. We sought to measure its utilization among practices that provide primary care for children who are enrolled in a prospective influenza surveillance study.

METHODS

This study included children aged 0.5-17 years who presented with fever or acute respiratory symptoms to an emergency department or inpatient setting in Winston-Salem, North Carolina, from September 1, 2009, through May 19, 2010. Study team members verified influenza and pneumococcal immunization status by requesting records from each child's primary care practice and by independently reviewing the NCIR. We assessed agreement of nonregistry immunization medical records with NCIR data using the kappa statistic.

RESULTS

Fifty-six practices confirmed the immunization status of 292 study-enrolled children. For most children (238/292, 82%), practices verified the child's immunizations by providing a copy of the NCIR record. For 54 children whose practices verified their immunizations by providing practice records alone, agreement with the NCIR by the kappa statistic was 0.6-0.7 for seasonal and monovalent H1N1 influenza vaccines and 0.8-0.9 for pneumococcal conjugate and polysaccharide vaccines. A total of 221 (98%) of 226 enrolled children younger than 6 years of age had 2 or more immunizations documented in the NCIR.

LIMITATIONS

NCIR usage may vary in other regions of North Carolina.

CONCLUSION

More than 95% of children younger than 6 years of age had 2 or more immunizations documented in the NCIR; thus, the Centers for Disease Control and Prevention 2010 goal for immunization information systems was met in this population. We found substantial agreement between practice records and the NCIR for influenza and pneumococcal immunizations in children.

Disparities between black and white children in hospitalizations associated with acute respiratory illness and laboratory-confirmed influenza and respiratory syncytial virus in 3 US counties--2002-2009

Few US studies have assessed racial disparities in viral respiratory hospitalizations among children. This study enrolled black and white children under 5 years of age who were hospitalized for acute respiratory illness (ARI) in 3 US counties during October-May 2002-2009. Population-based rates of hospitalization were calculated by race for ARI and laboratory-confirmed influenza and respiratory syncytial virus (RSV), using US Census denominators. Relative rates of hospitalization between racial groups were estimated. Of 1,415 hospitalized black children and 1,824 hospitalized white children with ARI enrolled in the study, 108 (8%) black children and 111 (6%) white children had influenza and 230 (19%) black children and 441 (29%) white children had RSV. Hospitalization rates were higher among black children than among white children for ARI (relative rate (RR) = 1.7, 95% confidence interval (CI): 1.6, 1.8) and influenza (RR = 2.1, 95% CI: 1.6, 2.9). For RSV, rates were similar among black and white children under age 12 months but higher for black children aged 12 months or more (for ages 12-23 months, RR = 1.7, 95% CI: 1.1, 2.5; for ages 24-59 months, RR = 2.2, 95% CI: 1.3, 3.6). Black children versus white children were significantly more likely to have public insurance or no insurance (85% vs. 43%) and a history of asthma/wheezing (28% vs. 18%) but not more severe illness. The observed racial disparities require further study.

The burden of influenza in young children, 2004-2009

OBJECTIVE

To characterize the health care burden of influenza from 2004 through 2009, years when influenza vaccine recommendations were expanded to all children aged ≥6 months.

METHODS

Population-based surveillance for laboratory-confirmed influenza was performed among children aged <5 years presenting with fever and/or acute respiratory illness to inpatient and outpatient settings during 5 influenza seasons in 3 US counties. Enrolled children had nasal/throat swabs tested for influenza by reverse transcriptase-polymerase chain reaction and their medical records reviewed. Rates of influenza hospitalizations per 1000 population and proportions of outpatients (emergency department and clinic) with influenza were computed.

RESULTS

The study population comprised 2970, 2698, and 2920 children from inpatient, emergency department, and clinic settings, respectively. The single-season influenza hospitalization rates were 0.4 to 1.0 per 1000 children aged <5 years and highest for infants <6 months. The proportion of outpatient children with influenza ranged from 10% to 25% annually. Among children hospitalized with influenza, 58% had physician-ordered influenza testing, 35% had discharge diagnoses of influenza, and 2% received antiviral medication. Among outpatients with influenza, 7% were tested for influenza, 7% were diagnosed with influenza, and <1% had antiviral treatment. Throughout the 5 study seasons, <45% of influenza-negative children ≥6 months were fully vaccinated against influenza.

CONCLUSIONS

Despite expanded vaccination recommendations, many children are insufficiently vaccinated, and substantial influenza burden remains. Antiviral use was low. Future studies need to evaluate trends in use of vaccine and antiviral agents and their impact on disease burden and identify strategies to prevent influenza in young infants.

Potential impact of parental Tdap immunization on infant pertussis hospitalizations

We estimated the potential impact of parental Tdap immunization before delivery, at delivery and at the 2-week newborn visit on U.S. infant pertussis hospitalizations. We used published data for pertussis hospitalization rates among U.S. infants aged 0-4 months, the Tdap vaccine efficacy in adults, and the proportion of infants with pertussis <6 months of age in which either parent was the source (16-40% from mothers and 16-20% from fathers). Immunizing parents before pregnancy or ≥ 2 weeks prior to delivery should reduce pertussis hospitalizations among infants 0-4 months by 2694-9314 if both parents are vaccinated, and by 1347-6909 if only mothers are vaccinated. Greater reductions in pertussis hospitalizations would be achieved if parents are immunized ≥ 2 weeks prior to delivery than after delivery or the 2-week newborn visit. Although immunizing parents prior to pregnancy or delivery is best, immunizing parents in the postpartum period should provide protection to that newborn and to infants of subsequent pregnancies.

Potential impact of accelerating the primary dose of rotavirus vaccine in infants

We estimated the potential impact of administering the first dose of rotavirus vaccine at 6 weeks (42 days of life) instead of 2 months of age, which is permissible for all U.S. vaccines recommended at 2 months of age, on rotavirus hospitalization rates. We used published data for hospitalization rates, vaccine coverage, and vaccine efficacy after one dose and assumed a two-week delay in seroconversion after vaccine administration in the United States. Administering the first dose of rotavirus vaccine at 6 weeks instead of 8 weeks of age should have prevented 1110, 1660, and 2210 rotavirus hospitalizations among U.S. infants <3 months of age in 2006 when the vaccine was first introduced. This estimated benefit represents a 2-4% reduction in rotavirus hospitalizations among children <5 years of age.

Detection of group A Streptococcus in tonsils from pediatric patients reveals high rate of asymptomatic streptococcal carriage

Background

Group A Streptococcus (GAS) causes acute tonsillopharyngitis in children, and approximately 20% of this population are chronic carriers of GAS. Antibacterial therapy has previously been shown to be insufficient at clearing GAS carriage. Bacterial biofilms are a surface-attached bacterial community that is encased in a matrix of extracellular polymeric substances. Biofilms have been shown to provide a protective niche against the immune response and antibiotic treatments, and are often associated with recurrent or chronic bacterial infections. The objective of this study was to test the hypothesis that GAS is present within tonsil tissue at the time of tonsillectomy.

Methods

Blinded immunofluorescent and histological methods were employed to evaluate palatine tonsils from children undergoing routine tonsillectomy for adenotonsillar hypertrophy or recurrent GAS tonsillopharyngitis.

Results

Immunofluorescence analysis using anti-GAS antibody was positive in 11/30 (37%) children who had tonsillectomy for adenotonsillar hypertrophy and in 10/30 (33%) children who had tonsillectomy for recurrent GAS pharyngitis. Fluorescent microscopy with anti-GAS and anti-cytokeratin 8 & 18 antibodies revealed GAS was localized to the tonsillar reticulated crypts. Scanning electron microscopy identified 3-dimensional communities of cocci similar in size and morphology to GAS. The characteristics of these communities are similar to GAS biofilms from in vivo animal models.

Conclusion

Our study revealed the presence of GAS within the tonsillar reticulated crypts of approximately one-third of children who underwent tonsillectomy for either adenotonsillar hypertrophy or recurrent GAS tonsillopharyngitis at the Wake Forest School of Medicine.

Trial Registration

The tissue collected was normally discarded tissue and no patient identifiers were collected. Thus, no subjects were formally enrolled.

2009-2010 seasonal influenza vaccination coverage among college students from 8 universities in North Carolina

OBJECTIVE

The authors sought to describe the 2009-2010 seasonal influenza vaccine coverage of college students.

PARTICIPANTS

A total of 4,090 college students from 8 North Carolina universities participated in a confidential, Web-based survey in October-November 2009.

METHODS

Associations between self-reported 2009-2010 seasonal influenza vaccination and demographic characteristics, campus activities, parental education, and e-mail usage were assessed by bivariate analyses and by a mixed-effects model adjusting for clustering by university.

RESULTS

Overall, 20% of students (range 14%-30% by university) reported receiving 2009-2010 seasonal influenza vaccine. Being a freshman, attending a private university, having a college-educated parent, and participating in academic clubs/honor societies predicted receipt of influenza vaccine in the mixed-effects model.

CONCLUSIONS

The self-reported 2009-2010 influenza vaccine coverage was one-quarter of the 2020 Healthy People goal (80%) for healthy persons 18 to 64 years of age. College campuses have the opportunity to enhance influenza vaccine coverage among its diverse student populations.

Assessment of parental report for 2009-2010 seasonal and monovalent H1N1 influenza vaccines among children in the emergency department or hospital

OBJECTIVE

To assess the validity of parental report for seasonal and monovalent H1N1 influenza vaccinations among children 6 months to <18 years who were recommended to receive both vaccines in 2009-2010.

METHODS

Children with fever or respiratory symptoms were prospectively enrolled in both emergency departments in Forsyth County, North Carolina, and the only pediatric hospital in the region. Enrollment occurred from September 1, 2009, through April 12, 2010, during the H1N1 influenza pandemic. A parental questionnaire was administered by trained interviewers to ascertain the status of seasonal and monovalent H1N1 influenza vaccines. Parental report was compared with that documented in the medical record and/or the North Carolina immunization registry.

RESULTS

Among 297 enrolled children 6 months to <18 years of age, 174 (59%) were 6 months to 4 years, 67 (23%) were 5-8 years, and 56 (19%) were 9 to <18 years. Parents reported that 140 (47%) children had received ≥1 dose of 2009-2010 influenza vaccine-128 (43%) for seasonal vaccine and 63 (21%) for H1N1 vaccine. Confirmed vaccination data indicated that 156 (53%) children had received ≥1 dose of any 2009-2010 vaccine-120 (40%) for seasonal vaccine and 53 (18%) for H1N1 vaccine. Parental report of any seasonal influenza vaccination was 92% sensitive and 86% specific and had a kappa of 0.76. Parental report for any H1N1 influenza vaccination was 88% sensitive and 92% specific with a kappa of 0.71.

CONCLUSIONS

Parental report of 2009-2010 seasonal and monovalent H1N1 influenza vaccinations was sensitive and specific and had reasonable agreement with the medical record and/or immunization registry.

Vaccine effectiveness for laboratory-confirmed influenza in children 6-59 months of age, 2005-2007

To estimate the effectiveness of influenza vaccine against medical care visits for laboratory-confirmed influenza in young children we conducted a matched case-control study in children with acute respiratory illness or fever from 2005-2007. Influenza vaccine effectiveness (VE) was calculated using cases with laboratory-confirmed influenza and controls who tested negative for influenza. The effectiveness of influenza vaccine in fully vaccinated children 6-59 months of age was 56% (95% CI: 25%-74%); a significant VE was not found for partial vaccination.

Impact of maternal immunization on influenza hospitalizations in infants

We sought to determine whether maternal vaccination during pregnancy was associated with a reduced risk of laboratory-confirmed influenza hospitalizations in infants <6 months old. Active population-based, laboratory-confirmed influenza surveillance was conducted in children hospitalized with fever and/or respiratory symptoms in 3 US counties from November through April during the 2002 through 2009 influenza seasons. The exposure, influenza vaccination during pregnancy, and the outcome, positive/negative influenza testing among their hospitalized infants, were compared using logistic regression analyses. Among 1510 hospitalized infants <6 months old, 151 (10%) had laboratory-confirmed influenza and 294 (19%) mothers reported receiving influenza vaccine during pregnancy. Eighteen (12%) mothers of influenza-positive infants and 276 (20%) mothers of influenza-negative infants were vaccinated (unadjusted odds ratio, 0.53; 95% confidence interval, 0.32-0.88 and adjusted odds ratio, 0.52; 95% confidence interval, 0.30-0.91). Infants of vaccinated mothers were 45-48% less likely to have influenza hospitalizations than infants of unvaccinated mothers. Our results support the current influenza vaccination recommendation for pregnant women.

Practice and child characteristics associated with influenza vaccine uptake in young children

OBJECTIVES

The objective of this study was to determine both practice and child characteristics and practice strategies associated with receipt of influenza vaccine in young children during the 2004-2005 influenza season, the first season for the universal influenza vaccination recommendation for all children who are aged 6 to 23 months.

METHODS

Clinical and demographic data from randomly selected children who were aged 6 to 23 months were obtained by chart review from a community-based cohort study in 3 US counties. The proportion of children who were vaccinated by April 5, 2005, in each practice was obtained. For assessment of practice characteristics and strategies, sampled practices received a self-administered practice survey. Practice and child characteristics that predicted complete influenza vaccination were determined by using multinomial logistic regression.

RESULTS

Forty-six (88%) of 52 sampled practices completed the survey and permitted chart reviews. Of 2384 children who were aged 6 to 23 months and were studied, 27% were completely vaccinated. The proportion of children who were completely vaccinated varied widely among practices (0%-71%). Most (87%) practices implemented ≥1 vaccination strategy. Complete influenza vaccination was associated with 3 practice characteristics: suburban location, lower patient volume, and vaccination strategies of evening/weekend vaccine clinics; with child characteristics of younger age, existing high-risk conditions, ≥6 well visits to the practice by 3 years of age, and any practice visit from October through January.

CONCLUSIONS

Modifiable factors that were associated with increased influenza vaccination coverage included October to January practice visits and evening/weekend vaccine clinics.

Failure of routine diagnostic methods to detect influenza in hospitalized older adults

OBJECTIVE

To define the utility of using routine diagnostic methods to detect influenza in older, hospitalized adults.

DESIGN

Descriptive study.

SETTING

One academic hospital and 1 community hospital during the 2006-2007 and 2007-2008 influenza seasons. Participants. Hospitalized adults 50 years of age or older.

METHODS

Adults who were 50 years of age or older and hospitalized with symptoms of respiratory illness were enrolled and tested for influenza by use of reverse-transcriptase polymerase chain reaction (RT-PCR). Using RT-PCR as the gold standard, we assessed the performances of rapid antigen tests and conventional influenza culture and the diagnostic use of the clinical definition of influenza-like illness.

RESULTS

Influenza was detected by use of RT-PCR in 26 (11%) of 228 patients enrolled in our study. The sensitivity of the rapid antigen test performed at bedside by research staff members was 19.2% (95% confidence interval, 8.51%-37.9%); the sensitivity of conventional influenza culture was 34.6% (95% confidence interval, 19.4%-53.8%). The ability to detect influenza with both the rapid antigen test and culture was associated with patients with a higher viral load (P=.002 and P=.001, respectively). The ability to diagnose influenza by use of the clinical definition of influenza-like illness had a higher sensitivity (80.8%) but lacked specificity (40.6%).

CONCLUSION

Because rapid antigen testing and viral culture have poor sensitivity (19.2% and 34.6%, respectively), neither testing method is sufficient to use to determine what type of isolation procedures to implement in a hospital setting.

Sickle cell trait, hemoglobin C trait, and invasive pneumococcal disease

BACKGROUND

The cause of historically higher rates of invasive pneumococcal disease among blacks than whites has remained unknown. We tested the hypothesis that sickle cell trait or hemoglobin C trait is an independent risk factor for invasive pneumococcal disease.

METHOD

Eligible children were born in Tennessee (1996-2003), had a newborn screen, enrolled in TennCare aged <1 year, and resided in a Tennessee county with laboratory-confirmed, pneumococcal surveillance. Race/ethnicity was ascertained from birth certificates. Children were followed through 2005 until loss of enrollment, pneumococcal disease episode, fifth birthday, or death. We calculated incidence rates by race/ethnicity and hemoglobin type before and after pneumococcal conjugate vaccine (PCV7) introduction. Poisson regression analyses compared invasive pneumococcal disease rates among blacks with sickle cell trait or hemoglobin C trait with whites and blacks with normal hemoglobin, controlling for age, gender, time (pre-PCV7, transition year, or post-PCV7) and high-risk conditions (eg, heart disease).

RESULTS

Over 10 years, 415 invasive pneumococcal disease episodes occurred during 451,594 observed child-years. Before PCV7 introduction, disease rates/100,000 child-years were 2941 for blacks with sickle cell disease, 258 for blacks with sickle cell trait or hemoglobin C trait and 188, 172, and 125 for blacks, whites, and Hispanics with normal hemoglobin. Post-PCV7, rates declined for all groups. Blacks with sickle cell trait or hemoglobin C trait had 77% (95% CI = 22-155) and 42% (95% CI = 1-100) higher rates than whites and blacks with normal hemoglobin.

CONCLUSION

Black children with sickle cell trait or hemoglobin C trait have an increased risk of invasive pneumococcal disease.

Potential impact of accelerating the primary dose of pneumococcal conjugate vaccine in infants

OBJECTIVE

To estimate the potential effect of the acceleration of administration of the first dose of pneumococcal conjugate vaccine from 2 months to 6 weeks of age.

DESIGN

Prediction model using data from a retrospective cohort study.

SETTING

Published data from 8 states that participated in Active Bacterial Core Surveillance of the Emerging Infections Program Network for pneumococcus before pneumococcal conjugate vaccine introduction (July 1, 1997- June 30, 2000).

PARTICIPANTS

A total of 759 739 live births under surveillance. Intervention Estimating the potential benefit of administration of the first dose of the pneumococcal conjugate vaccine at 6 weeks of age instead of 2 months of age.

MAIN OUTCOME MEASURES

Estimation of reduction in the rate of invasive pneumococcal disease in infants 61 to 90 days of age.

RESULTS

The estimated direct effect of the acceleration of administration of the first dose of pneumococcal conjugate vaccine from 2 months to 6 weeks of age when this vaccine was first introduced could have reduced the burden of invasive pneumococcal disease in infants 61 to 90 days of age by 39.9%, 56.0%, and 72.1% for respective vaccine efficacies of 50%, 70%, and 90%. This translates into preventing an estimated 73, 103, and 133 cases of invasive pneumococcal disease per year among approximately 4 112 052 live births in the United States.

CONCLUSIONS

The acceleration of administration of the pneumococcal conjugate vaccine from 2 months to 6 weeks of age could reduce the burden of invasive pneumococcal disease among infants. This observation may be important when a new conjugate vaccine becomes available, particularly among populations with prevalent invasive pneumococcal disease from a serotype included in the new vaccine.

The burden of respiratory syncytial virus infection in young children

BACKGROUND

The primary role of respiratory syncytial virus (RSV) in causing infant hospitalizations is well recognized, but the total burden of RSV infection among young children remains poorly defined.

METHODS

We conducted prospective, population-based surveillance of acute respiratory infections among children under 5 years of age in three U.S. counties. We enrolled hospitalized children from 2000 through 2004 and children presenting as outpatients in emergency departments and pediatric offices from 2002 through 2004. RSV was detected by culture and reverse-transcriptase polymerase chain reaction. Clinical information was obtained from parents and medical records. We calculated population-based rates of hospitalization associated with RSV infection and estimated the rates of RSV-associated outpatient visits.

RESULTS

Among 5067 children enrolled in the study, 919 (18%) had RSV infections. Overall, RSV was associated with 20% of hospitalizations, 18% of emergency department visits, and 15% of office visits for acute respiratory infections from November through April. Average annual hospitalization rates were 17 per 1000 children under 6 months of age and 3 per 1000 children under 5 years of age. Most of the children had no coexisting illnesses. Only prematurity and a young age were independent risk factors for hospitalization. Estimated rates of RSV-associated office visits among children under 5 years of age were three times those in emergency departments. Outpatients had moderately severe RSV-associated illness, but few of the illnesses (3%) were diagnosed as being caused by RSV.

CONCLUSIONS

RSV infection is associated with substantial morbidity in U.S. children in both inpatient and outpatient settings. Most children with RSV infection were previously healthy, suggesting that control strategies targeting only high-risk children will have a limited effect on the total disease burden of RSV infection.

Influenza in older adults: impact of vaccination of school children

The extent to which immunizing school children reduce the burden of influenza in adults is controversial. We enrolled a systematic sample of adults > or = 50 years hospitalized with respiratory symptoms in two counties, one with and one without a school-based immunization program. We tested all subjects for influenza by polymerase chain reaction. Hospitalizations per 1000 adults aged > or = 50 years were 1.28 (95% CI 0.59, 2.04) in the intervention county and 1.53 (95% CI 0.71, 2.34) in the control county. These rates did not differ significantly except in the subgroup aged 50 -- 64 years where rates in the intervention county were significantly lower.

Potential impact of acceleration of the pertussis vaccine primary series for infants

OBJECTIVE

This study estimates the potential impact, on rates of pertussis infections, hospitalizations, and deaths among infants in the United States, of administering the first dose of diphtheria and tetanus toxoids and acellular pertussis vaccine at 6 weeks rather than 2 months of age.

METHODS

We used existing data to estimate current US rates of pertussis infections, hospitalizations, and deaths according to age and infant population in 2004. We then estimated the potential impact of accelerating the administration of the first dose of diphtheria and tetanus toxoids and acellular pertussis vaccine from 2 months to 6 weeks of age, an alternative schedule consistent with current vaccination guidelines. We used Poisson distribution analysis to determine 95% confidence intervals for projected rates of pertussis disease.

RESULTS

Acceleration of administration of the first dose of diphtheria and tetanus toxoids and acellular pertussis vaccine from 2 months to 6 weeks of age is expected to prevent 1236 cases of pertussis, 898 hospitalizations, and 7 deaths attributable to pertussis per year in the United States. These decreases represent 9% reduction in cases, 9% reduction in hospitalizations, and 6% reduction in deaths attributable to pertussis among infants <3 months of age. Acceleration of the second and third doses by 2 weeks is expected to prevent an additional 923 cases, 520 hospitalizations, and 2 deaths attributable to pertussis each year.

CONCLUSION

Acceleration of administration of diphtheria and tetanus toxoids and acellular pertussis vaccine from 2 months to 6 weeks should reduce the burden of pertussis among young infants.

Vaccine effectiveness against laboratory-confirmed influenza in children 6 to 59 months of age during the 2003-2004 and 2004-2005 influenza seasons

OBJECTIVE

The goal was to estimate the effectiveness of influenza vaccination against laboratory-confirmed influenza during the 2003-2004 and 2004-2005 influenza seasons in children 6 to 59 months of age.

METHODS

We conducted a case-control study with children with medically attended, acute respiratory infections who received care in an inpatient, emergency department, or outpatient clinic setting during 2 consecutive influenza seasons. All children residing in Monroe County, New York, Davidson County, Tennessee, or Hamilton County, Ohio, were enrolled prospectively at the time of acute illness and had nasal/throat swabs tested for influenza with cultures and/or polymerase chain reaction assays. Children with laboratory-confirmed influenza were case subjects and children who tested negative for influenza were control subjects. Child vaccination records from the parent and the child's physician were used to determine and to validate influenza vaccination status. Influenza vaccine effectiveness was calculated as (1 - adjusted odds ratio) x 100.

RESULTS

We enrolled 288 case subjects and 744 control subjects during the 2003-2004 season and 197 case subjects and 1305 control subjects during the 2004-2005 season. Six percent and 19% of all study children were fully vaccinated according to immunization guidelines in the respective seasons. Full vaccination was associated with significantly fewer influenza-related inpatient, emergency department, or outpatient clinic visits in 2004-2005 (vaccine effectiveness: 57%) but not in 2003-2004 (vaccine effectiveness: 44%). Partial vaccination was not effective in either season.

CONCLUSIONS

Receipt of all recommended doses of influenza vaccine was associated with halving of laboratory-confirmed influenza-related medical visits among children 6 to 59 months of age in 1 of 2 study years, despite suboptimal matches between the vaccine and circulating influenza strains in both years.

Influenza burden for children with asthma

OBJECTIVE

The goal was to estimate the influenza disease burden among children with asthma and among healthy children by using active, laboratory-confirmed, population-based surveillance.

METHODS

Children 6 to 59 months of age residing in 3 US counties who were hospitalized with acute respiratory illnesses or fever were enrolled prospectively from 2000 through 2004. Similar children who presented to clinics and emergency departments during 2 of the influenza seasons (2002-2004) were enrolled. Rates of influenza-attributable outpatient visits and hospitalizations for children with asthma and for healthy children were estimated. History of asthma and receipt of influenza vaccine for the study children were determined through parental report. The prevalence of asthma in the surveillance population was assumed to be 6.2% for children 6 to 23 months of age and 12.3% for children 24 to 59 months of age.

RESULTS

Of 81 children 6 to 59 months of age with influenza-confirmed hospitalizations in 2000 to 2004, 19 (23%) had asthma. Average annual influenza-attributable hospitalization rates were significantly higher among children with asthma than among healthy children 6 to 23 months of age (2.8 vs 0.6 cases per 1000 children) but not children 24 to 59 months of age (0.6 vs 0.2 case per 1000 children). Of 249 children 6 to 59 months of age with influenza-confirmed outpatient visits in 2002 to 2004, 38 (15%) had asthma. Estimated outpatient influenza-attributable visit rates were higher among children with asthma than among healthy children 6 to 23 months of age (316 vs 152 cases per 1000 children) and 24 to 59 months of age (188 vs 102 cases per 1000 children) in 2003 to 2004. Few parents reported that their children had been vaccinated, including <30% of children with asthma.

CONCLUSION

Influenza-attributable health care utilization is high among children with asthma and is generally higher than among healthy children.

Validity of parental report of influenza vaccination in children 6 to 59 months of age

OBJECTIVE

The objective of this study was to assess the validity of parental report of influenza vaccinations.

PATIENTS AND METHODS

A cross-sectional study of children who were 6 to 59 months of age and presented to a large, pediatric residency clinic from February through April 2005 was performed. A standardized, parental questionnaire ascertained the influenza vaccination status of children during the 2004-2005 influenza season and was compared with the medical chart, the criterion standard. Children were classified as being at high risk when they had a specific influenza vaccine recommendation in 2004-2005 by age (6-23 months of age) or by chronic medical condition.

RESULTS

Of 218 parents approached in the pediatric residency clinic, 198 (95%) children who were 6 to 59 months of age were enrolled, and 84 (42%) were vaccinated according to the medical chart. More children who were 6 to 23 months than those who were 24 to 59 months of age were vaccinated (63% vs 21%). Children with chronic medical conditions were more likely to be vaccinated than healthy children who were 24 to 59 months of age (57% vs 11%), but no difference was observed for children who were 6 to 23 months of age (79% vs 60%). In comparison with the medical chart, parental report of influenza vaccination had a sensitivity of 88%, a specificity of 90%, and a kappa coefficient of 0.78. For children who were 6 to 23 months of age or had a chronic medical condition (n = 123), parental report had a sensitivity of 89%, a specificity of 81%, and a kappa coefficient of 0.71.

CONCLUSIONS

Parental report of influenza vaccination among children who were 6 to 59 months of age had reasonable sensitivity, specificity, and reliability as compared with the medical chart in this study population.