Acellular pertussis vaccine use in risk groups (adolescents, pregnant women, newborns and health care workers): A review of evidences and recommendations

Comparative Evaluation of Recombinant and Acellular Pertussis Vaccines in a Murine Model

Since the 2000s, sporadic outbreaks of whooping cough have been reported in advanced countries, where the acellular pertussis vaccination rate is relatively high, and in developing countries. Small-scale whooping cough has also continued in many countries, due in part to the waning of immune protection after childhood vaccination, necessitating the development of an improved pertussis vaccine and vaccination program. Currently, two different production platforms are being actively pursued in Korea; one is based on the aP (acellular pertussis) vaccine purified from B. pertussis containing pertussis toxoid (PT), filamentous hemagglutin (FHA) and pertactin (PRN), and the other is based on the recombinant aP (raP), containing genetically detoxified pertussis toxin ADP-ribosyltransferase subunit 1 (PtxS1), FHA, and PRN domain, expressed and purified from recombinant E. coli. aP components were further combined with diphtheria and tetanus vaccine components as a prototype DTaP vaccine by GC Pharma (GC DTaP vaccine). We evaluated and compared the immunogenicity and the protective efficacy of aP and raP vaccines in an experimental murine challenge model: humoral immunity in serum, IgA secretion in nasal lavage, bacterial clearance after challenge, PTx (pertussis toxin) CHO cell neutralization titer, cytokine secretion in spleen single cell, and tissue resident memory CD4+ T cell (CD4+ TRM cell) in lung tissues. In humoral immunogenicity, GC DTaP vaccines showed high titers for PT and PRN and showed similar patterns in nasal lavage and IL-5 cytokine secretions. The GC DTaP vaccine and the control vaccine showed equivalent results in bacterial clearance after challenge, PTx CHO cell neutralization assay, and CD4+ TRM cell. In contrast, the recombinant raP vaccine exhibited strong antibody responses for FHA and PRN, albeit with low antibody level of PT and low titer in PTx CHO neutralization assay, as compared to control and GC DTaP vaccines. The raP vaccine provided a sterile lung bacterial clearance comparable to a commercial control vaccine after the experimental challenge in murine model. Moreover, raP exhibited a strong cytokine response and CD4+ TRM cell in lung tissue, comparable or superior to the experimental and commercial DTaP vaccinated groups. Contingent on improving the biophysical stability and humoral response to PT, the raP vaccine warrants further development as an effective alternative to aP vaccines for the control of a pertussis outbreak.

Review of scientific evidence to support recommendations of the full-dose DTaP-IPV vaccination in pre-school age children in Italy

INTRODUCTION

Two vaccine formulations are available to prevent diphtheria, tetanus, pertussis, and poliomyelitis: the pediatric full-dose (DTaP-IPV) and the reduced dose formulation (dTap-IPV). Different immunization schedules are internationally recommended for the pre-school booster dose.

AREAS COVERED

International and Italian recommendations, scientific evidence on immunogenicity and safety of DTaP/dTap vaccines to support the full dose as a pre-school booster and Italian vaccination coverage (VC) up to adolescence.

EXPERT OPINION

The WHO recommends a '3+1' schedule with DTaP vaccine for primary immunization, followed by a pre-school booster with DTaP or dTap vaccine. In Italy, a '2+1' schedule, with no booster in the second year, and a pre-school booster dose are recommended with DTPa-IPV vaccines. Studies showed a non-inferior immunogenicity in dTap vaccinees in pre-school age; nevertheless, the antibody titers were usually greater in children vaccinated with DTaP, while lower frequencies of adverse events were recorded in children receiving dTap. Italian VCs for pre-school and adolescent boosters have not been satisfactory, which further reduced during the COVID-19 period. In Italy, the pre-school booster offers the last chance to receive a full dose of DTaP vaccine, thus, representing the most suitable intervention to provide lasting protection in children.

Immunogenicity of a new enhanced tetanus-reduced dose diphtheria-acellular pertussis (Tdap) vaccine against Bordetella pertussis in a murine model

Background

The necessity of the tetanus-reduced dose diphtheria-acellular pertussis (Tdap) vaccine in adolescence and adults has been emphasized since the resurgence of small-scale pertussis in Korea and worldwide due to the waning effect of the vaccine and variant pathogenic stains in the late 1990s. GreenCross Pharma (GC Pharma), a Korean company, developed the Tdap vaccine GC3111 in 2010. Recently, they enhanced the vaccine, GC3111, produced previously in 2010 to reinforce the antibody response against filamentous hemagglutinin (FHA). In this study, immunogenicity and efficacy of the enhanced Tdap vaccine compared and evaluated with two Tdap vaccines, GC3111 vaccine produced in 2010 previously and commercially available Tdap vaccine in a murine model.

Methods

Two tests groups and positive control group of Balb/c mice were primed with two doses of the diphtheria-tetanus-acellular pertussis (DTaP) vaccine followed by a single booster Tdap vaccine at 9 week using the commercially available Tdap vaccine or 2 Tdap vaccines from GC Pharma (GC3111, enhanced GC3111). Humoral response was assessed 1 week before and 2 and 4 weeks after Tdap booster vaccination. The enhanced GC3111 generated similar humoral response compare to the commercial vaccine for filamentous hemagglutinin (FHA). The interferon gamma (IFN-γ) (Th1), interleukin 5 (IL-5) (Th2) and interleukin 17 (IL-17) (Th17) cytokines were assessed 4 weeks after booster vaccination by stimulation with three simulators: heat inactivated Bordetella pertussis (hBp), vaccine antigens, and hBp mixed with antigens (hBp + antigen). A bacterial challenge test was performed 4 weeks after booster vaccination.

Results

Regarding cell-mediated immunity, cytokine secretion differed among the three simulators. However, no difference was found between two test groups and positive control group. All the vaccinated groups indicated a Th1 or Th1/Th2 response. On Day 5 post-bacterial challenge, B. pertussis colonies were absent in the lungs in two test groups and positive control group.

Conclusions

Our results confirmed the immunogenicity of GC Pharma’s Tdap vaccine; enhanced GC3111 was equivalent to the presently used commercial vaccine in terms of humoral response as well as cell-mediated cytokine expression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-021-00457-1.

Clinical characteristics of 967 children with pertussis: a single-center analysis over an 8-year period in Beijing, China

The purpose of this study is to understand children’s clinical characteristics with pertussis and analyze risk factors on critical pertussis patients. Demographic data from patients with pertussis at Children’s Hospital affiliated to the Capital Institute of Pediatrics between March 2011 and December 2018 were collected. We retrospectively gathered more information with the positive exposure, vaccination, antibiotic usage before diagnosis, clinical manifestation, laboratory tests, therapy, and complications for hospitalized children. We divided the patients into severe and non-severe groups, comparing related factors and clinical characteristics among each group. In particular, we summarize the clinical features of the severe patients before aggravation. A total of 967 pertussis cases were diagnosed, of which 227 were hospitalized. The onset age younger than 3 months old accounted for the highest proportion, and 126 patients received hospitalization. For those patients, the incidence of post-tussive vomiting, paroxysmal cyanosis, post-tussive heart rate decrease, hypoxemia, severe pneumonia, and mechanical ventilation was significantly higher than that in the ≥ 3-month-old group (p < 0.05). Among 227 hospitalized patients, 54 suffered from severe pertussis. Risk factors for severe patients included early age of onset, pathogen exposure, and unvaccinated status. Cough paroxysms, post-tussive vomiting, paroxysmal cyanosis, facial flushing/cyanosis/fever during cough, increased WBC, and chest X-ray revealing pneumonia/consolidation/atelectasis were important indications of severe pertussis. Unvaccinated status was an independent risk factor for severe pertussis. The most vulnerable population was infants < 3 months old to pertussis, and may be on the severe end of the disease. Pediatricians must detect and treat severe cases promptly and recommend timely vaccination for all eligible children.

Pertussis immunisation during pregnancy: Antibody levels and the impact of booster vaccine

Pertussis (whooping cough) is a highly infectious disease caused by Bordetella pertussis. Mothers lacking adequate immunity and contracting the disease represent the biggest risk of transmission to new-borns, for which the disease is often a threat. The aim of the study was to estimate the frequency of pertussis susceptibility among pregnant women, in order to point out the need for a vaccine recall during pregnancy, and to evaluate the antibody response in already vaccinated women. A cross-sectional observational study was conducted in the blood test centre of "St. Anna" Obstetrics and Gynaecology Hospital in Turin (Piedmont, Italy). Eligibility criteria included pregnant women coming to the centre for any blood test, aged 18 or above and with gestational age between 33 and 37 weeks at the moment of the blood draw. The data collection was carried out from May 2019 to January 2020 and the concentration of anti-Pertussis Toxin (anti-PT) IgG was measured through the Enzyme-Linked Immunosorbent Assay (ELISA) technique. Two-hundred women (median age 35) were enrolled: 132 (66%) had received at least one dose of pertussis vaccine, 82 of which during pregnancy. Recently vaccinated women had significantly higher antibody titres (even 12-15 times as high) compared to those vaccinated more than 5 years before or never vaccinated at all (p < 0.0001). Moreover, 95.1% of recently vaccinated women had anti-PT IgG levels above 10 IU/ml, and 85.4% above 20 IU/ml, while the same proportions were as low as 37% and 21% (respectively) in the group of women not vaccinated in pregnancy. This study confirmed that the vaccination is greatly effective in ensuring high antibody titres in the first months after the booster vaccine, with considerable differences in anti-PT IgG compared to women vaccinated earlier or never vaccinated at all, and therefore vaccinating pregnant women against pertussis still represents a valuable strategy.

Determinants of policy and uptake of national vaccine programs for pregnant women: results of mixed method study from Spain, Italy, and India

An important strategy for addressing maternal and newborn risks of disease is through vaccinating pregnant women. We conducted a mixed-methods study including a narrative literature review of drivers of maternal vaccination and key informant interviews in Spain, Italy, and India to characterize different approaches to national maternal immunization programs. Fifty-nine respondents participated in the study conducted between November 2018 and January 2019. Policies in Spain and Italy both reflect a life-course approach to vaccination, but recommendations and how they ensure uptake differs. Italy was focused on tracking of progress and mandates to ensure compliance in all regions, while Spain, an early adopter, relied more on advocacy and building provider acceptance. India includes Td in their national program, but the political will and advocacy for other vaccines are not seen. Needs for improving rates of maternal vaccination include education of health-care providers and pregnant women, use of central registries to track progress, stronger global guidance for use of vaccines, and engagement of champions, particularly obstetrician-gynecologists (ob-gyns). Health security concerns can also be leveraged to build political priority and needed platforms to detect disease and deliver vaccines in some countries. Understanding what drives a country’s maternal immunization program decisions and the success of implementation is useful in designing strategies to share best practices and guide support to strengthen platforms for maternal vaccination.

Association of weather variability with resurging pertussis infections among different age groups: A non-linear approach

Pertussis has resurged in many countries over recent years, especially among adolescents and adults. This study assessed the effect of weather variability on resurging pertussis among different age groups in Jinan, China. Data on weekly pertussis notifications by age group and weather factors (mean temperature (MeanT), mean temperature standard deviation within a week (MeanT SD), diurnal temperature range (DTR) and relative humidity (RH)) were collected between 2013 and 2017. Distributed lag non-linear models (DLNMs) and regression tree models were used to examine the non-linear association between weather variability and pertussis infections. The 2-weeks cumulative relative risk (RR) of pertussis infections was 4.46 (95% confidence interval (CI): 2.33-9.51) in 0-4 age group, 6.25 (95% CI: 1.38-22.76) in 5-9 age group and 10.11 (95% CI: 2.83-39.07) in 10+ age group when MeanT was at 30.0 °C. MeanT SD (RR range in the three age groups: 2.82-5.83), DTR (RR range: 6.33-11.56) and RH (RR range: 2.02-7.43) also exert significant influence, with the highest risks at 10+ age group. Regression tree models showed the interactive effects of weather variability. The mean pertussis infections increased by over 1.7-fold in 0-4 years group when MeanT ≥14 °C, RH ≥57% and DTR ≥10 °C; by over 2.3-fold in 5-9 years group when MeanT ≥20 °C and MeanT SD ≥3 °C; by 2.0-fold in 10+ years group when MeanT ≥0.7 °C, DTR ≥8.3 °C and RH ≥74%. The study found significantly different associations between weather variability and pertussis infections by age group, and appeared to be stronger in 10+ years group. Continuing climate change, together with other risk factors such as low antibody levels among adolescents and adults, may facilitate pertussis resurgence. This supports previous suggestions of carefully reconsidering current vaccination programme to effectively curb the resurgence of pertussis.

Development and implementation of standardized method for detecting immunogenicity of acellular pertussis vaccines in Korea

Purpose

There is no standard method for confirming the immunogenicity of acellular pertussis vaccines. We tried to develop a local standard method for evaluating the immunogenicity of the three-component of acellular pertussis vaccines which was developed by a Korean local company.

Materials and Methods

The developed pertussis antigens (pertussis toxin, filamentous hemagglutinin, pertactin) were evaluated by in-house enzyme-linked immunosorbent assay (ELISA) using 189 negative sera, 25 positive sera, and 73 paired sera (pre- and post-Tdap [tetanus, diphtheria, and acellular pertussis] vaccinated sera). ELISA units were calculated by the reference line method, compared with World Health Organization reference sera, and the cut-off value was calculated using negative sera.

Results

When compared to National Institute for Biological Standards and Control control antigen (NIBSC) control antigens, the developed pertussis toxin (PT) and filamentous haemagglutinin (FHA) antigens were 203.48 and 61.60 IU/µg, respectively. Each in-house ELISA was established by validating the coefficients of variation % (PT, 11.53%; FHA, 8.60%; pertactin [PRN], 9.86%) obtained from the results of inter- and intra-assay variation. Also, the cut-off values of PT, FHA, and PRN were 11.65, 38.95, and 5.66 EU/mL, respectively. The distributions of antibody levels in paired showed that 93.15% (68/73) in anti-PT IgG, 97.26% (72/73) in anti-FHA IgG, and 100% in anti-PRN IgG were higher than a 100% increase after vaccination. Additionally, the values of 89.04% (65/73) in anti-PT IgG, 97.26% (72/73) in anti-FHA IgG, and 100% in anti-PRN IgG were below each cut-off point.

Conclusion

We established an in-house ELISA method using self-developed antigens, and these immunoassays have provided a way to standardize measuring the immunogenicity of newly developed vaccines, through single- and dual-serology.

Systematic review found that there was moderate evidence that vaccinating healthcare workers prevented pertussis in infants

This systematic review investigated the effectiveness of vaccinating healthcare workers against pertussis on the occurrence of nosocomial pertussis outbreaks or infections among unprotected infants. We focused on eight studies, with five different study designs, that involved 39,129 healthy adolescents and adults, 115 healthcare workers, 2000 simulated healthcare workers and a simulated population of 200,000 people.

CONCLUSION

There was moderate evidence that tetanus-diphtheria acellular pertussis vaccinations for healthcare workers were effective in preventing pertussis in all age groups and specifically in infants. The results must be interpreted with caution due to the low quality and heterogeneity of the studies.

Perceptions and practice of health care workers regarding hepatitis B vaccination, Bouaké, Côte d'Ivoire, 2016

Barriers to immunization are seen in both the general population and the health care workforce. We conducted this study to determine the perception of health workers on vaccination and the immunization of their patients. This cross-sectional descriptive analytical study was carried out among the medical staff in Bouaké, from 10 January to 07 March 2016. The data collected from the interviews were analyzed using Epi info 2000 software and SPSS 17.0. The Chi-2 test and logistic regression were performed and the significance threshold of the tests was 5%. The vaccination status of the 291 health care workers (HCWs) for the hepatitis B virus (HBV) was statistically related to their participation in the course in vaccination during their training (ORa = 1.69, 95% CI: 1.04-2.75 P<0.05) and the systematic verification of the vaccination status of the patient was statistically related to the vaccination status of the HCW (ORa = 4.33, 95% CI: 2.97-8.18, P<0.05). Promoting the vaccination among the population should be dependent on the promotion among HCWs.

Comparison of school based and supplemental vaccination strategies in the delivery of vaccines to 5-19 year olds in Africa - a systematic review

Background: Some vaccine preventable diseases (VPDs) still remain a public health burden in many African countries. The occurrence of VPDs in all age groups has led to the realization of the need to extend routine immunisation services to school age children, adolescents and adults. Supplemental immunisation activities (SIAs) and school based vaccinations (SBVs) are common strategies used to complement the expanded programme on immunisation (EPI). This review aimed to assess the effectiveness of SIAs compared to SBVs in the administration of vaccines to 5-19 year olds in Africa.

Methods: Systematic review methods were used to address our study aim. Several electronic databases were searched up to March 30, 2017 for primary studies investigating the delivery of vaccines via SIAs or SBVs to 5-19 year olds. This search was complemented by browsing reference lists of potential studies obtained from search outputs. Outcomes considered for inclusion were: vaccination coverage, costs of the strategy or its effect on routine immunisation services.

Results: Out of the 4938 studies identified, 31 studies met the review inclusion criteria. Both SIAs and SBVs showed high vaccination coverage. However, the SIAs reported higher coverage than SBVs: 91% (95% CI: 84%, 98%) versus 75% (95% CI: 67%, 83%). In most settings, SBVs were reported to be more expensive than SIAs. The SIAs were found to negatively affect routine immunisation services.

Conclusions: Both SIAs and SBVs are routinely used to complement the EPI in the delivery of vaccines in Africa. In settings where school enrolment is suboptimal, as is the case in many African countries, our results show SIAs may be more effective in reaching school age children and adolescents than SBVs. Our results re-iterate the importance of evaluating systematic evidence to best inform African authorities on the optimal vaccine delivery strategies targeting school age children and adolescents.

Focusing on the implementation of 21st century vaccines for adults

Adult immunization is a priority for public health, particularly in countries where an aging population has become increasingly more numerous. Protection against diseases which typically affect adults (like flu, pneumococcal diseases and Herpes zoster), the shift of age of infections which originally affected children (like measles), the decreasing protection with time for infections which need periodical booster doses of vaccines (Tdap), the availability of vaccines which can also impact on adult health (HPV) are only some examples of the importance of implementing targeted vaccination strategies. The possibility to reach high coverage with immunizations that can guarantee a fundamental improvement of health for adults and the elderly can only be achieved through a coordinated effort where all stakeholders, under the coordination of public health, contribute to issue recommendations; create a functioning database for vaccine coverage registration; promote formative courses for healthcare workers and continuous information for the public; increase vaccines uptake among healthcare workers, who need to give the first testimony on the relevance of immunization.

Knowledge, Attitude and Behaviours towards Recommended Vaccinations among Healthcare Workers

Healthcare workers (HCWs) are an important group of professionals exposed to biological risk during their work activities. So, the aim of this study is to perform a survey on the knowledge, attitude and behaviour of Italian HCWs towards the vaccinations recommended by the Ministry of Health. A cross-sectional study was carried out during the period September 2014–August 2015 in the Lazio region. The study was conducted by recruiting HCWs and biomedical students. The sample was comprised of 571 responders, of whom 12.4% were physicians, 18.9% were nurses, 34.3% were other HCW, and 34.3% were biomedical students (medical and nurses students). Hepatitis B virus (HBV) is perceived as a risk for personal health by 457 (80%) participants; TB is also worrying (434; 76%). Moreover, HBV (70.9%) and tuberculosis (TB) (79.2%) are perceived as a risk for health, while influenza is not considered so by most participants (46.2%). There is an underestimation of the role of influenza, perceived as a risk for 137 respondents (24%). The vaccination rate among these HCWs is highest for Hepatitis B virus (HBV) (82%), and lowest for influenza (28.5%) and varicella (40.3%). The vast majority of responders are in favour of HBV (77.8%) and TB (64.8%) vaccines. For other vaccinations there is less interest (between 33% and 40% for measles, mumps, rubella, pertussis and influenza). This study shows that knowledge of recommended occupational vaccinations is insufficient in HCWs, with few exceptions represented by HBV and TB. There is a need for novel approaches in this field, with the aim of enhancing vaccine coverage among HCW.

Risk factors for pertussis in adults and teenagers in England

Pertussis is a vaccine-preventable respiratory infection caused by Bordetella pertussis which can be fatal in infants. Although high vaccine coverage led to prolonged disease control in England, a national outbreak of pertussis in 2011 led to the largest increase in over two decades, including a marked increase in cases aged ⩾15 years. A case-control study in four regions of England was undertaken to investigate risk factors for pertussis in adolescents and adults, specifically employment type and professional and household contact with children. Pertussis cases were laboratory-confirmed and aged ⩾15 years. Controls were recruited through general practitioner nomination. Demographic and risk factor information were collected using an online survey. Multivariable logistic regression was used to estimate independent associations with outcome. Two hundred and thirty-one cases and 190 controls were recruited. None of the four employment variables (social care, education, health sector, patient contact) were significantly associated with pertussis. Professional contact with children aged < 1 year was associated with a significantly reduced odds of pertussis [odds ratio (OR) 0·25, 95% confidence interval (CI) 0·08–0·78, P = 0·017]. Household contact with ⩾1 child aged 10–14 years was associated with significantly increased odds of pertussis (OR 2·61, 95% CI 1·47–4·64, P = 0·001). Occupational contact with very young children was associated with reduced odds of pertussis, probably due to immune boosting by low-level exposures to B. pertussis. Sharing a household with a young adolescent was a significant risk factor for pertussis in adults and older teenagers. The primary focus of the childhood pertussis vaccination programmes is to prevent infant disease. Although evidence is emerging that adolescent vaccination does not provide indirect protection to infants, our results highlight the importance of children aged 10–14 years in pertussis transmission to older adolescents and adults.

ADVICE for a healthier life: Adult Vaccination Campaign in Europe

Immunization is one of the most effective public health measures to prevent disease. Despite relatively good vaccination rates in childhood in many parts of the world, vaccines to prevent diseases are underused in the adult population and adult vaccination rates are still far below the target. The European Federation of Internal Medicine (EFIM), declared that 'internal medicine must focus on better care for individuals, better health care for populations and lower costs'. Adult vaccination is a good example of a public health initiative aimed at reducing morbidity and mortality, but awareness of the need for adult vaccination and uptake of the programs across Europe is variable. The Adult Vaccination Campaign in Europe (ADVICE) was developed with an aim to raise awareness for adult vaccination and to understand the dynamics of the vaccination practices and the possible barriers against achieving targeted vaccination rates in Europe. In order to reach vaccination targets, we need evidence based, up to date guidelines; recommendations at national and international levels; surveillance for vaccination rates; and opportunities to provide vaccines more readily. Leadership at a European level and a firm research and action agenda are crucial. The European Federation of Internal Medicine can take the lead as it declared its interest on 'better care for individuals, better health care for populations'. Hence, we consider ADVICE a very timely and very valuable initiative to draw a roadmap to improve adult vaccination rates in Europe.

Vaccination of healthcare workers: A review

Vaccine-preventable diseases are a significant cause of morbidity and mortality. As new vaccines are proving to be effective and as the incidence of some infections decreases, vaccination practices are changing. Healthcare workers (HCWs) are particularly exposed to and play a role in nosocomial transmission, which makes them an important target group for vaccination. Most vaccine-preventable diseases still carry a significant risk of resurgence and have caused outbreaks in recent years. While many professional societies favor vaccination of HCWs as well as the general population, recommendations differ from country to country. In turn, vaccination coverage varies widely for each microorganism and for each country, making hospitals and clinics vulnerable to outbreaks. Vaccine mandates and non-mandatory strategies are the subject of ongoing research and controversies. Optimal approaches to increase coverage and turn the healthcare workforce into an efficient barrier against infectious diseases are still being debated.

Protecting Newborns Against Pertussis: Treatment and Prevention Strategies

Pertussis is a potentially severe respiratory disease, which affects all age groups from young infants to older adults and is responsible for an estimated 195,000 deaths occurred globally in 2008. Active research is ongoing to better understand the pathogenesis, immunology, and diagnosis of pertussis. For diagnosis, molecular assays (e.g., polymerase chain reaction) for detection of Bordetella pertussis have become more widely available and support improved outbreak detection. In children, pertussis vaccines have been incorporated into routine immunization schedules and deployed for pertussis outbreak control. Lower levels of vaccine coverage are now being observed in communities where vaccine hesitancy is rising. Additionally, recognition that newborn babies are at risk of pertussis in the USA and UK has led to recommendations to immunize pregnant women. Among adolescents and older adults in the USA, Tetanus Toxoid, Reduced Diphtheria Toxoid and Acellular pertussis (Tdap) Vaccines are recommended, but substantial individual- and system-level barriers exist that will make achieving national Healthy People 2020 targets for immunization challenging. Current antimicrobial regimens for pertussis are focused on reducing the severity of disease, reducing rates of sequelae, and minimizing transmission of infection to susceptible individuals. Continued surveillance for pertussis will be important to identify opportunities for reducing young infants' exposure and reducing the impact of outbreaks among school-aged children. Laboratory-based surveillance for newly emerging strains of B. pertussis will be important to identify strains that may evade protection elicited by currently available vaccines. Efforts to develop new-generation pertussis vaccines should be considered now in anticipation of vaccine development programs, which may require ten or more years to deliver a licensed vaccine.

Promoting Tdap immunization in pregnancy: Associations between maternal perceptions and vaccination rates

OBJECTIVE

Tdap vaccine uptake among US pregnant women is low despite current recommendations. This study evaluated if a Tdap vaccine information statement (VIS) affected overall perception, vaccination intention, and components of a health behavior model associated with Tdap vaccination rates.

METHODS

A randomized, prospective study was conducted among pregnant women receiving care at two women's clinics in May-August 2014. Verbally consented participants were randomized to receive either the standard CDC Tdap VIS (sVIS) or a modified version (mVIS) before completing the first multi-part survey (T1). After T1, participants read their assigned VIS then completed the second part (T2). A 2015 chart review identified vaccinated participants. A health behavior model was hypothesized using the Reasoned Action Approach and Health Belief Model. Logistic regression, path analysis, and chi-square tests were used in the analysis.

RESULTS

279 surveys were analyzed. Average age of the participants was 26.4 years (SD=5.7) with average gestational age of 25.9 weeks (SD=9.2). 13% self-reported receiving Tdap vaccine prior to the survey. Overall perception scores significantly increased (3.1-3.4, p<0.001) after VIS review. A chart review showed that 131 (47%) received the vaccine post study. There was no significant difference in vaccination rates between the sVIS and mVIS groups (45% vs. 49%). Perceived benefits (B=0.315) and self-efficacy (B=0.197) were positively associated with the overall perception (T1), while perceived barriers (B=-0.191) were negatively associated with the overall perception (T1). Social norms (B=0.230), self-efficacy (B=0.213), and perceived benefits (B=0.117) were positively associated with vaccination intention (T1). The vaccination intention (T2) was positively associated with participants' decision to receive Tdap vaccine (B=0.223).

CONCLUSION

A VIS improved overall perception of the Tdap vaccine. Vaccination intention was a predictor of Tdap vaccination. It is crucial to provide information about immunization benefits to promote maternal Tdap vaccination.

Vaccination of adolescents with chronic medical conditions: Special considerations and strategies for enhancing uptake

Adolescents with chronic medical conditions (CMCs), a growing population worldwide, possess a wide array of preventive health care needs. Vaccination is strongly recommended for the vast majority of these adolescents given their increased risk of vaccine preventable infection and associated complications. Not only should they receive routine vaccines, but some also require additional vaccines. Despite these guidelines, evidence suggests that adolescents with CMCs often fail to receive needed vaccines. Many factors contribute to this under-immunization, including lack of knowledge among parents and providers and suboptimal coordination of primary and subspecialty care. This review describes current vaccination recommendations for these adolescents as well as recent data related to infection risk, vaccine efficacy and safety, vaccination coverage, and the unique multilevel factors impacting uptake in this population. It also discusses strategies for improving coverage levels and reducing missed vaccination opportunities, with a particular focus on technology-based interventions.

Assessment of antibody level and avidity against Bordetella pertussis in a cohort of Egyptian individuals aged 1-18 years

Pertussis specific antibodies were studied with respect to quality and quantity in a cohort of apparently healthy Egyptian children and adolescents, with their age range between 1 and 18 years, in an attempt to get a close and clear insight into the current humoral immunization status in this specified group and to try find a relation between the antibody levels and their avidities in eradication of this devastating infectious disease. Our results showed that avidity increase was most marked in young school children (6–8 years) where it seemed to reach a plateau in older children and adolescents. Antibody titer was highest in toddlers (1–2 years) and young school children (6–8 years) groups, most probably following vaccination and/or booster doses. Among children aged 1–5 years, 28% had highly avid and 50% had high titer antibodies, whereas in adolescents aged 13–18 years, 70% had highly avid antibodies and only 30% had high titer antibodies. The results clearly demonstrated that while levels of anti-Bordetella pertussis (B. pertussis) antibodies wane with growing age, the avidity seems to increase, to a plateau, irrespective of further antigen exposure in a pattern showing complete independence of avidity on concentration. The present study draws attention to the importance of avidity measurements, together with conventional ELISAs, for evaluating immunity against pertussis. Being based on a limited sample size, it could open doors for larger-scale surveys to be possible indicators for the need and timing of booster vaccination doses among Egyptians.

Pertussis outbreak in university students and evaluation of acellular pertussis vaccine effectiveness in Japan

BACKGROUND

Recent studies worldwide have reported increasing numbers of adults diagnosed with Bordetella pertussis despite receiving childhood vaccinations. This study describes a pertussis outbreak at a university medical faculty campus and examines the effectiveness of diphtheria, tetanus, and pertussis (DTaP) vaccination completed during infancy in Japan.

METHODS

After the outbreak, self-administered questionnaires and serum samples were collected from students on campus to determine the incidence of pertussis and underlying diseases. Pertussis was diagnosed on the basis of clinical criteria and serum anti-pertussis toxin antibody levels. Using data collected from 248 first and second grade students who had submitted copies of their vaccination records, we evaluated the effectiveness of DTaP vaccination in infancy against adult pertussis.

RESULTS

Questionnaire responses were obtained from 636 students (of 671 registered students; 95% response rate). Of 245 students who reported a continuous cough during the outbreak period, 84 (attack rate: 13.2%) were considered "probable" pertussis cases that met clinical criteria. The outbreak occurred mainly in first and second grade students in the Faculty of Medicine. Of 248 students who provided vaccination records, 225 had received 4 DTaP doses (coverage: 90.7%); the relative risk of the complete vaccination series compared to those with fewer than 4 doses or no doses for probable cases was 0.48 (95% confidence interval: 0.24-0.97).

CONCLUSIONS

Waning protection was suspected due to over time. Booster vaccination for teenagers and development of highly efficacious pertussis vaccines are needed.

Pertussis

Pertussis continues to be an important public-health issue. The high immunization coverage rates achieved, mainly in industrialized countries, have certainly decreased the spread of the pathogen. However, as immunity wanes, adolescents and adults play an important role in the dynamics of the infection. The surveillance system has several limitations and the underestimation of pertussis in adolescents, young adults and adults is mainly related to the atypical clinical characteristics of cases and the lack of lab confirmation. The real epidemiological impact of pertussis is not always perceived. The unavailability of comprehensive data should not hamper the adoption of active prophylactic measures designed to avoid the impact of waning immunity against pertussis. Different immunization strategies have been suggested and/or already adopted such as immunization of newborns, pre-school and school children, adolescents, adults, healthcare workers, childcare workers, pregnant women, cocoon strategy. Prevention of pertussis requires an integrated approach and the adoption of different immunization strategies, with the objective of achieving and maintaining high coverage rates.

Attitude toward immunization and risk perception of measles, rubella, mumps, varicella, and pertussis in health care workers working in 6 hospitals of Florence, Italy 2011

BACKGROUND

Health care workers (HCWs) are at risk of infection and transmission of vaccine-preventable infectious diseases. In recent years cases of measles or varicella in health care workers were observed with increasing frequency. The aim of our study was to investigate attitude toward immunization and risk perception of measles, rubella, mumps, varicella, and pertussis in HCWs working in 6 hospitals of Florence (Italy).

METHODS

A cross-sectional survey among the physicians, nurses, midwives, and nursing assistants working in selected departments was performed trough a self-administered, anonymous questionnaire. Overall, 600 questionnaires were sent and 436 HCWs' completed forms were included into the study (Participation rate: 72.7%). Data were analyzed with STATA 11.0® and odds ratio (OR) were calculated in a multivariate analysis.

RESULTS

Among all respondents 74.9% were females. The average age was nearly 43-years-old (42.9-SD 8.95). The majority of participants (58.6%) were nurses, 21.3% physicians, 12.9% nursing assistants, and 7.2% were midwives. Among those HCWs reporting no history of disease, 52.8% (95% CI: 42.0-63.3%) declared to have been immunized for measles, 46.9% for rubella (95% CI: 39.0-54.9%), 21.6% for mumps (95% CI: 15.1-29.4%), 14.9% for varicella (95% CI: 7.4-25.7%), and 14.5% for pertussis (95% CI: 10.0-20.0%). When considering potentially susceptible HCWs (without history of disease or vaccination and without serological confirmation), less than a half of them feel at risk for the concerned diseases and only less than 30% would undergo immunization. One of the main reasons of the relatively low coverage was indeed lack of active offer of vaccines.

CONCLUSION

Attitudes toward immunization observed in this study are generally positive for preventing some infectious diseases (i.e., measles and rubella), but relatively poor for others (i.e., varicella). More information should be made available to HCWs on the benefits of vaccination and efforts to encourage vaccination uptake should be performed. Educational program on the risk of being infected working in a hospital should be implemented in order to increase the risk perception toward infectious diseases among HCWs.

Child and adolescent immunizations: selected review of recent US recommendations and literature

PURPOSE OF REVIEW

To provide a clinically relevant summary of the latest research and recommendations regarding childhood and adolescent immunizations.

RECENT FINDINGS

Childhood vaccination has dramatically reduced pediatric morbidity and mortality in the United States. Recent research on childhood and adolescent immunizations has focused on expanding the use of current vaccines for additional subpopulations as well as the development of new vaccines. In particular, data confirming the safety and immunogenicity of vaccines in various groups of children have shaped national guidelines. Furthermore, studies on vaccine uptake, cost-effectiveness, and impact of vaccination have reinforced the importance of adhering to these guidelines. More work needs to be done by providers and parents to increase vaccination coverage rates to better protect children and adolescents from these serious diseases. In this article, selected recent publications and recommendations on the following vaccines are reviewed: influenza, meningococcal conjugate, childhood and adolescent/adult formulations of diphtheria and tetanus toxoids and acellular pertussis, pneumococcal conjugate, and human papillomavirus.

SUMMARY

Research on childhood and adolescent vaccinations continues to shape future guidelines. Through this work, we can learn how to optimize the protection of all children and adolescents against vaccine-preventable diseases.

[Vaccination and pregnancy]

Vaccination against influenza is recommended during the vaccination period in pregnant women regardless of trimester. In contrast, administration of live vaccines, such as the vaccine against varicella, MMR (measles-mumps-rubella) is contraindicated in pregnant women. Vaccinations against hepatitis B, diphtheria, tetanus, poliomyelitis, hepatitis A can be made as indicated. Vaccination against yellow fever may be considered in pregnant women travelling to endemic countries. In post-partum period, live vaccines may be administered if necessary, especially vaccination against whooping cough for women not to date with their vaccinations. Vaccination against yellow fever is contraindicated in case of breast feeding. Prevention of pertussis in newborns is based in France on vaccination of the mothers in the post-partum period, and the close contacts of the newborn during the pregnancy ("cocooning").

Updated treatment and prevention guidelines for pertussis

Pertussis, commonly referred to as whooping cough, is one of the top 10 causes of death in children globally despite vaccine availability. Adhering to vaccination guidelines for both the primary childhood series as well as adolescent and adult boosters is crucial in preventing the spread of disease. However, due to vaccine failure, outbreaks occur every 3 to 5 years. As a result, early recognition and prompt treatment are instrumental in controlling the epidemic.

Healthcare workers as vectors of infectious diseases

Nosocomial infections cause considerable morbidity and mortality. Healthcare workers (HCWs) may serve as vectors of many infectious diseases, many of which are not often primarily considered as healthcare-associated. The probability of pathogen transmission to patients depends on several factors, such as the characteristics of a pathogen, HCW and patient. Pathogens with high transmission potential from HCWs to patients include norovirus, respiratory infections, measles and influenza. In contrast, human immunodeficiency virus (HIV) and viral hepatitis are unlikely to be transferred. The prevention of HCW-associated transmission of pathogens include systematic vaccinations towards preventable diseases, continuous education, hand hygiene surveillance, active feedback and adequate staff resources.

The issue of mandatory vaccination for healthcare workers in Europe

Mandatory policies have occasionally been implemented, targeting optimal vaccination uptake among healthcare workers (HCWs). Herein, we analyze the existing recommendations in European countries and discuss the feasibility of implementing mandatory vaccination for HCWs. As reflected by a survey among vaccine experts from 29 European countries, guidelines on HCW vaccination were issued in all countries, though with substantial differences in targeted diseases, HCW groups and type of recommendation. Mandatory policies were only exceptionally implemented. Results from a second survey suggested that such policies would not become easily adopted, and recommendations might work better if focusing on specific HCW groups and appropriate diseases such as hepatitis B, influenza and measles. In conclusion, guidelines for HCW vaccination, but not mandatory policies, are widely adopted in Europe. Recommendations targeting specific HCW groups and diseases might be better accepted and facilitate higher vaccine uptake than policies vaguely targeting all HCW groups.

Immunogenicity and safety after booster vaccination of diphtheria, tetanus, and acellular pertussis in young adults: an open randomized controlled trial in Japan

The recent increase of pertussis in young adults in Japan is hypothesized to be due in part to waning protection from the acellular pertussis vaccine. While a booster immunization may prevent an epidemic of pertussis among these young adults, little is known about the safety and immunogenicity of such a booster with the diphtheria, tetanus, and acellular pertussis vaccine (DTaP), which is currently available in Japan. One hundred and eleven medical students with a mean age of 19.4 years were randomly divided into 2 groups of 55 and 56 subjects and received, respectively, 0.2 or 0.5 ml of DTaP. Immunogenicity was assessed by performing the immunoassay using serum, and the geometric mean concentration (GMC), GMC ratio (GMCR), seropositive rate, and booster response rate were calculated. Adverse reactions and adverse events were monitored for 7 days after vaccination. After booster vaccination in the two groups, significant increases were found in the antibodies against pertussis toxin, filamentous hemagglutinin, diphtheria toxoid, and tetanus toxoid, and the booster response rates for all subjects reached 100%. The GMCs and GMCRs against all antigens were significantly higher in the 0.5-ml group than in the 0.2-ml group. No serious adverse events were observed. Frequencies of local reactions were similar in the 2 groups, although the frequency of severe local swelling was significantly higher in the 0.5-ml group. These data support the acceptability of booster immunization using both 0.2 and 0.5 ml of DTaP for young adults for controlling pertussis. (This study was registered at UMIN-CTR under registration number UMIN000010672.).

Report of a pertussis outbreak in a low coverage booster vaccination group of otherwise healthy children in Italy

Background

The introduction of universal pertussis immunization and the high coverage achieved in most developed countries have largely changed the epidemiology of the disease. Although vaccination rates are high in the first year of life, the rates of booster doses are unsatisfactory and lead to the onset of outbreaks. This report describes an outbreak of pertussis affecting school students already immunized in a town of Puglia (Italy), detected at the end of April 2009.

Methods

Vaccine effectiveness is measured by calculating the incidence rates (attack rates- AR) of disease among vaccinated (ARV) and unvaccinated (ARU) people and determining the percentage reduction in the incidence rate of disease among vaccinated people compared to unvaccinated people.

Results

The index case was a healthy child, female, 9-years-old who attended a local elementary school and developed pertussis on 27 April 2009. The secondary cases were the aunt and the cousin of the index case who developed a cough on 10 May 2009. In the elementary class of the index case, a cluster occurred. The overall AR was 15.8%, in particular 20% in children who did not receive the booster doses at 5–6 years old (ARU) and 14.3% in children receiving the booster (ARV). The VE of booster dose in this setting was 28.5%. Moreover, only the index case developed a persistent cough; the VE against moderate to severe pertussis was 100%. A cluster was detected in the middle school class that the cousin of the index case attended; AR was 44.4% (12/27); ARU was 50% (10/20) and ARV 28.6% (2/7). VE in this setting was 42.8%.

Conclusions

Our results confirm the need to administer booster doses; failure the booster is the principal determinant for the outbreak onset.

Ethics of mandatory vaccination for healthcare workers

Healthcare workers (HCWs) are at increased risk of contracting infections at work and further transmitting them to colleagues and patients. Immune HCWs would be protected themselves and act as a barrier against the spread of infections and maintain healthcare delivery during outbreaks, but vaccine uptake rates in HCWs have often been low. In order to achieve adequate immunisation rates in HCWs, mandatory vaccination policies are occasionally implemented by healthcare authorities, but such policies have raised considerable controversy. Here we review the background of this debate, analyse arguments for and against mandatory vaccination policies, and consider the principles and virtues of clinical, professional, institutional and public health ethics. We conclude that there is a moral imperative for HCWs to be immune and for healthcare institutions to ensure HCW vaccination, in particular for those working in settings with high-risk groups of patients. If voluntary uptake of vaccination by HCWs is not optimal, patients’ welfare, public health and also the HCW’s own health interests should outweigh concerns about individual autonomy: fair mandatory vaccination policies for HCWs might be acceptable. Differences in diseases, patient and HCW groups at risk and available vaccines should be taken into consideration when adopting the optimal policy.

Perceptions of Tetanus-diphteria-acellular pertussis (Tdap) Vaccination among Korean Women of Childbearing Age

BACKGROUND

The number of cases of pertussis reported has increased gradually in the last decade. Pertussis vaccination is the most effective strategy for the prevention of infection. Despite the fact that young infants are at the highest risk for pertussis, the rate of tetanus-diphtheria-acellular pertussis (Tdap) vaccination is presumed to be very low among women of childbearing age in Korea. The purpose of this study was to investigate the perceptions of women of childbearing age regarding Tdap vaccination in Korea.

MATERIALS AND METHODS

Women of childbearing age, who visited the Department of Obstetrics and Gynecology at 3 University hospitals in the Seoul and Gyeonggi-do provinces of Korea, were surveyed. Individual questionnaires were administered from April to May 2012. Demographic data, Tdap vaccination history, general knowledge about pertussis, and information on factors associated with decision on vaccination were collected.

RESULTS

Of the 500 reproductive-age women enrolled, only 4 (0.8%) had received the Tdap. The most common reason for non-vaccination was the lack of awareness of pertussis and information about the Tdap. Totally, 171 (34.2%) responded that they would receive a Tdap vaccination in the future. By multivariate analysis, general confidence in the effectiveness of the vaccine (odds ratio [OR] = 1.88, 95% confidence interval [CI] 1.17 to 3.01) was indicated as an important factor for deciding whether to receive the Tdap vaccine (P < 0.01).

CONCLUSIONS

The coverage of Tdap vaccination of women of childbearing age, including pregnant women, is very low because of the lack of awareness of pertussis and the Tdap. Education of women of childbearing age about pertussis is very important to increase Tdap vaccination rates among these women, particularly during the perinatal period.

Update on adolescent immunizations: selected review of US recommendations and literature

PURPOSE OF REVIEW

To provide a clinically relevant synopsis of recent research findings as well as updated recommendations from the American Academy of Pediatrics (AAP) and Advisory Committee on Immunization Practices (ACIP) regarding adolescent immunizations.

RECENT FINDINGS

Coverage rates for the adolescent vaccinations continue to lag behind those of the childhood vaccinations, despite their importance. Recent research has focused on the reasons for suboptimal adolescent vaccination rates as well as strategies for improvement. By more fully understanding the barriers to immunization, efforts can be implemented to address these concerns and to ensure that all eligible adolescents receive their vaccinations. In addition, much work has focused on the duration of protection induced by childhood and adolescent vaccinations and the need for booster doses in older adolescents. Because immunity has been found to wane after vaccination, these booster doses can serve to more fully protect adolescents. This article reviews selected recent publications on human papillomavirus, meningococcal conjugate, and tetanus and diphtheria toxoids and acellular pertussis vaccines.

SUMMARY

Adolescent vaccinations will continue to be studied and this research will serve to shape future recommendations. Through this work, we can learn the best methods to optimize the protection of all adolescents against these very serious diseases.

Pertussis: a review of disease epidemiology worldwide and in Italy

Pertussis continues to be a relevant public-health issue. The high coverage rates achieved have decreased the spread of the pathogen, but the waning of immunity implies a relevant role of adolescents and adults in the infective dynamics as they may represent a significant source of infection for unvaccinated or incompletely immunized newborns. The passive surveillance system is affected by many limitations. The underestimation of pertussis in adolescents, young adults and adults is mainly related to the atypical clinical characteristics of cases and the lack of lab confirmation. The real epidemiological impact of pertussis is not always perceived, anyway, the unavailability of comprehensive data should not hamper the adoption of active prophylactic interventions aimed at preventing the impact of waning immunity on pertussis. To avoid an increase of the mean age of acquisition of the infection, a booster dose of low-antigen content combined vaccine should be adopted in adolescents and adults. A decreased risk of infection in newborns can be achieved with the cocoon strategy, although the debate on this aspect is still open and enhanced surveillance and further studies are needed to fine-tune the pertussis prevention strategy.

Infectious diseases and vaccination strategies: how to protect the "unprotectable"?

Introduction. The circulation of infectious diseases puts small infants too young to be vaccinated at risk of morbidity and mortality, often requiring prolonged hospitalization. Material and Methods. We have reviewed the medical records of children not eligible for vaccination because of age, admitted to hospital for pertussis, measles, or varicella from February 1, 2010, till February 1, 2012. Results. Of the case records scrutinized, 21 were hospitalized for pertussis, 18 for measles, and 32 for varicella. Out of them, 42%, 66%, and 78% diagnosed with, respectively, pertussis, measles, and varicella had a complicated course of the disease. Discussion. To avoid infectious disease circulation, childhood immunization strategies should be adopted, such as vaccination of healthcare givers, adult household contacts, and parents planning to have, or who have had, a newborn baby.

Pertussis re-emergence in the post-vaccination era

BACKGROUND

Resurgence of pertussis in the post-vaccination era has been reported in Western countries. A shift of cases from school-age children to adolescents, adults and children under 1 year of age has been described in the last decade, and mortality rates in infants are still sustained. We aimed to review and discuss the possible vaccination strategies which can be adopted in order to improve the pertussis control, by searches of Pubmed, and websites of US and European Centers for Disease Control and Prevention, between 1st January 2002, and 1st March 2013.

DISCUSSION

The following vaccination strategies have been retrieved and analysed: the cocooning strategy, the immunization of pregnant women and newborns, vaccination programs for preschool children, adolescents, adults and health-care workers. Cost-effectiveness studies provide some contrasting data, mainly supporting both maternal vaccination and cocooning. Adolescent and/or adult vaccination seems to be cost-effective, however data from observational studies suggest that this vaccination strategy, used alone, leads to a reduced pertussis burden globally, but does not affect the disease incidence in infants. Moreover, substantial logistical and economic difficulties have to be overcome to vaccinate the largest number of individuals.

SUMMARY

The simultaneous use of more than one strategy, including cocooning strategy plus vaccination of adolescents and adults, seems to be the most reasonable preventive measure. The development of new highly immunogenic and efficacious pertussis vaccines continues to be a primary objective for the control of pertussis.