Need For Boosters Research Articles

Clinical spectrum and outcomes of the 2019-2020 pediatric diphtheria outbreak in Yemen

Background Diphtheria is an acute bacterial infectious disease characterized by serious morbidity and mortality. Outbreaks continue to occur in developing countries despite national vaccination programs. Vaccination, early recognition the disease, and adequate intervention are needed to avoid devastating outcomes.
 Objective To describe the clinical spectrum of childhood diphtheria and its association to outcomes during the 2019-2020 diphtheria outberak in Yemen.
 Methods This was a retrospective study to assess the demographic, clinical features, and outcomes of paediatric respiratory diphtheria in patients with diphtheria during the outbreak from September 2019 until May 2020 admitted at Mukalla Maternity and Children Hospital. We used SPSS 22 version for data analysis.
 Results There were 34 culture-confirmed diphtheria cases included in this study, their age ranged from 13 months to 15 years old. Most of the cases (76.5%) happened to children at more than 5 years old. There was no gender difference. Of these 34-positive diphtheria, 79.4% from Hadramout and 17.6% from Shabwa governorate. Most of the cases (35.3%) were admitted in December. More than half of the patients (52.9%) were unimmunized. Fever, sore throat, and enlarged tonsils were presented in all patients, dysphagia (82.4 %), pseudomembrane (91.7%), bull neck (52.9%), and stridor (8.8%) were also found in some patients. Complications included acute renal failure (20.6%), disseminated intravascular coagulation (DIC), shock (17.6%), and myocarditis (8.8%). Significant poor outcome (P< 0.05) was associated with bull neck, myocarditis, acute renal failure, DIC, and shock. The case fatality rate (CFR) was 20.6%.
 Conclusion Fever, sore throat, tonsillitis, pseudomembrane, and bull neck are high index suspicion of diphtheria and anticipation of ominous outcome. The shifting of occurrence of diphtheria to older age group indicates the need for booster(s) diphtheria toxoid vaccine in addition to improving and strengthening the current immunization program.

Modeling the response of an endangered rabbit population to RHDV2 and vaccination

AbstractRabbit hemorrhagic disease virus 2 (RHDV2), recently detected in the western United States, has the potential to cause mass mortality events in wild rabbit and hare populations. Currently, few management strategies exist other than vaccination. We developed a spatially explicit model of RHDV2 for a population of riparian brush rabbits (Sylvilagus bachmani riparius), a subspecies of brush rabbit classified as endangered in the United States, on a subsection of the San Joaquin River National Wildlife Refuge. The goal of our model was to provide guidance regarding vaccination strategies for an endangered rabbit species. Our model predicts that increased interactions between rabbits (a proxy for landscape connectivity) and disease transmission rates among susceptible hosts (individual brush rabbits and conspecifics) have the greatest influence on the outcome of a potential vaccination campaign. Our model projects that across a range of parameter estimates (given an RHDV2 incursion), the median estimated population size with a 0%–10% vaccination rate after 1 year is 538 rabbits (95% Confidence Interval [C.I.] 69–1235), approximately 36% of the expected size of the study population of 1470 rabbits without an RHDV2 introduction. With a 10%–20%, 20%–30%, or 30%–40% vaccination rate, the median estimated population size increased to 628 rabbits (95% C.I. 130–1298), 723 rabbits (95% C.I. 198–1317), and 774 rabbits (95% C.I. 228–1410), respectively. These estimates represent 43%, 49%, and 53% of the expected population size without an RHDV2 introduction. Overall, a 1% increase in vaccination rate was associated with a six rabbit (95% C.I. 5–7) increase in total remaining population size. This result is dependent on assumptions regarding environmental transmission, home range size (and contact rates of rabbits). Given the relatively short lifespan of rabbits and the potential need for boosters, vaccination programs are most likely to be successful for small target populations where relatively high vaccination rates can be maintained.

A single-dose MCMV-based vaccine elicits long-lasting immune protection in mice against distinct SARS-CoV-2 variants.

Current vaccines against COVID-19 elicit immune responses that are overall strong but wane rapidly. As a consequence, the necessary booster shots have contributed to vaccine fatigue. Hence, vaccines that would provide lasting protection against COVID-19 are needed, but are still unavailable. Cytomegaloviruses (CMVs) elicit lasting and uniquely strong immune responses. Used as vaccine vectors, they may be attractive tools that obviate the need for boosters. Therefore, we tested the murine CMV (MCMV) as a vaccine vector against COVID-19 in relevant preclinical models of immunization and challenge. We have previously developed a recombinant MCMV vaccine vector expressing the spike protein of the ancestral SARS-CoV-2 (MCMVS). In this study, we show that the MCMVS elicits a robust and lasting protection in young and aged mice. Notably, spike-specific humoral and cellular immunity was not only maintained but also even increased over a period of at least 6 months. During that time, antibody avidity continuously increased and expanded in breadth, resulting in neutralization of genetically distant variants, like Omicron BA.1. A single dose of MCMVS conferred rapid virus clearance upon challenge. Moreover, MCMVS vaccination controlled two variants of concern (VOCs), the Beta (B.1.135) and the Omicron (BA.1) variants. Thus, CMV vectors provide unique advantages over other vaccine technologies, eliciting broadly reactive and long-lasting immune responses against COVID-19.

Optimizing COVID-19 Vaccination Strategy in Pediatric Kidney Transplant Recipients: Humoral and Cellular Response to SARS-CoV-2 mRNA Vaccination.

In this retrospective cohort study, we analyze the early humoral and cellular response in 64 adolescents KTx recipients, after two or three doses of mRNA vaccine BNT162b2 against different variants of COVID-19. After 2 doses, 77.8% % of children with no history of infection had a positive humoral response with a median anti-S IgG level of 1107 (IQR, 593-2,658) BAU/mL. All the patients with a history of infection responded with a higher median IgG level (3,265 (IQR, 1,492-8,178) BAU/mL). In non-responders after 2 doses, 75% responded after a third dose with a median Ab titer at 355 (IQR, 140-3,865BAU/mL). Neutralizing activity was significantly lower against the delta and the omicron variants compared to the wild-type strain and did not improve after a 3rd dose, while infection did provide higher levels of neutralizations against the variants. T cell specific response correlated with humoral response and no patient displayed a cellular response without a humoral response. Adolescent KTx recipients exhibit a high seroconversion rate after only two doses. A third injection, induces a response in the majority of the non-responders patients but did not counterbalance the strong decrease in neutralizing antibody activities against variants highlighting the need for boosters with specific vaccines.

Innovative informatics interventions to improve health and health care.

In this editorial, I highlight 5 papers that address innovative informatics interventions—3 research studies and 2 reviews. The papers reflect a variety of information technologies and processes including mobile health (mHealth),1 behavioral nudges in the electronic health record (EHR),2 adaptive intervention framework,3 predictive models,4 and artificial intelligence (eg, machine learning, data mining, natural language processing).5 The interventions were designed to address important clinical and public health problems such as adherence to antiretroviral therapy for persons living with HIV (PLWH),1 opioid use disorder,3 and pain assessment and management,5 as well as aspects of healthcare quality including no-show rates for appointments4 and erroneous decisions, waste, and misuse of resources due to EHR choice architecture for clinician orders.3 Schnall et al1 completed a randomized controlled trial (RCT) to assess the efficacy of an mHealth self-management interventions for PLWH on antiretroviral adherence and viral suppression. The novel WiseApp intervention comprised testimonials of lived experiences, push-notification reminders, medication trackers, health surveys, chat rooms, and a daily “To-Do” list. In a sample of PLWH with suboptimal adherence, daily antiretroviral adherence was significantly higher in the WiseApp group as compared to attention control group from day 1 to day 59 but not for days 60–120. There were no significant differences in viral suppression. The authors suggest that there is a need for booster or a combination intervention approaches after the initial effects of the mHealth intervention wanes.

Long-Term Immunity Against Tetanus and Diphtheria after Vaccination of Allogeneic Stem Cell Transplantation Recipients

Revaccination against tetanus and diphtheria after allogeneic hematopoietic stem cell transplantation (HCT) is usually effective, but the duration of the immunity is unknown. We conducted this study to evaluate humoral immunity to tetanus and diphtheria in long-term survivors and to provide knowledge regarding the need for boosters. The median time from HCT to blood sampling was 14 years (range, 8 to 40 years). All patients had received at least 3 doses of vaccines against both tetanus and diphtheria, either monovalent or combination vaccines containing a full dose of the diphtheria toxoid component. In addition, 1 or more booster doses were administered to 21 of the 146 patients (14%). On enzyme-linked immunosorbent assay, levels <.1 IU/mL for diphtheria and <.01 IU/mL for tetanus were considered low or seronegative. Values between .01 and .5 IU/mL for tetanus and between .1 and 1.0 IU/mL for diphtheria were considered to represent partial protection, and levels >.5 and >1.0 IU/mL were considered high and protective, respectively. In all, 39% of patients were seronegative against diphtheria, 52% had some protection, and 9% had a high titer. In contrast, no patient had become seronegative to tetanus, 32% had "partial protection" against tetanus and 68% had a high titer. In multivariate analysis, active graft-versus-host-disease, sex, or time from sampling did not affect the probability of becoming seronegative or seropositive. Younger age was associated with lower antibody levels to tetanus toxoid, but age was not correlated with antibody levels against diphtheria toxoid. Tetanus immunity was maintained after vaccination in most long-term survivors, but immunity against diphtheria was poor, and boosters should be considered.

COVID-19 Vaccines' Protection Over Time and the Need for Booster Doses; a Systematic Review.

Introduction:Controversies existed regarding the duration of COVID-19 vaccines’ protection and whether receiving the usual vaccine doses would be sufficient for long-term immunity. Therefore, we aimed to systematically review the studies regarding the COVID-19 vaccines’ protection three months after getting fully vaccinated and assess the need for vaccine booster doses.Methods:The relevant literature was searched using a combination of keywords on the online databases of PubMed, Scopus, Web of Science, and Cochrane on September 17th, 2021. The records were downloaded and the duplicates were removed. Then, the records were evaluated in a two-step process, consisting of title/abstract and full-text screening processes, and the eligible records were selected for the qualitative synthesis. We only included original studies that evaluated the efficacy and immunity of COVID-19 vaccines three months after full vaccination. This review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement to ensure the reliability of results.Results:Out of the 797 retrieved records, 12 studies were included, 10 on mRNA-based vaccines and two on inactivated vaccines. The majority of included studies observed acceptable antibody titers in most of the participants even after 6 months; however,it appeared that the titers could also decrease in a considerable portion of people. Due to the reduction in antibody titers and vaccine protection, several studies suggested administering the booster dose, especially for older patients and those with underlying conditions, such as patients with immunodeficiencies.Conclusion:Studies indicated that vaccine immunity decreases over time, making people more susceptible to contracting the disease. Besides, new variants are emerging, and the omicron variant is continuing to spread and escape from the immune system, indicating the importance of a booster dose.

Variability in Severe Acute Respiratory Syndrome Coronavirus 2 IgG Antibody Affinity to Omicron and Delta Variants in Convalescent and Community mRNA-Vaccinated Individuals.

The emergence of the omicron and delta variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has begun a number of discussions regarding breakthrough infection, waning immunity, need and timing for vaccine boosters, and whether existing mRNA vaccines for the original SARS-CoV-2 strain are adequate. Our work leverages a biosensor-based technique to evaluate the binding efficacy of SARS-CoV-2 S1-specific salivary Abs to the omicron and delta variants using a cohort of mRNA-vaccinated (n = 109) and convalescent (n = 19) subjects. We discovered a wide range of binding efficacies to the variant strains, with a mean reduction of 60.5, 26.7, and 14.7% in measurable signal to the omicron strain and 13.4, 2.4, and -6.4% mean reduction to the delta variant for convalescent, Pfizer-, and Moderna-vaccinated groups, respectively. This assay may be an important tool in determining susceptibility to infection or need for booster immunization as the pandemic evolves.

Evaluating immunity to SARS-CoV-2 in nursing home residents using saliva IgG.

SARS-CoV-2 circulating variants coupled with waning immunity pose a significant threat to the long-term care (LTC) population. Our objective was to measure salivary IgG antibodies in residents and staff of an LTC facility to (1) evaluate IgG response in saliva post-natural infection and vaccination and (2) assess its feasibility to describe the seroprevalence over time. We performed salivary IgG sampling of all residents and staff who agreed to test in a 150-bed skilled nursing facility during three seroprevalence surveys between October 2020 and February 2021. The facility had SARS-CoV-2 outbreaks in May 2020 and November 2020, when 45 of 138 and 37 of 125 residents were infected, respectively; they offered two Federal vaccine clinics in January 2021. We evaluated quantitative IgG in saliva to the Nucleocapsid (N), Spike (S), and Receptor-binding domain (RBD) Antigens of SARS-CoV-2 over time post-infection and post-vaccination. One hundred twenty-four residents and 28 staff underwent saliva serologic testing on one or more survey visits. Over three surveys, the SARS-CoV-2 seroprevalence at the facility was 49%, 64%, and 81%, respectively. IgG to S, RBD, and N Antigens all increased post infection. Post vaccination, the infection naïve group did not have a detectable N IgG level, and N IgG levels for the previously infected did not increase post vaccination (p < 0.001). Fully vaccinated subjects with prior COVID-19 infection had significantly higher RBD and S IgG responses compared with those who were infection-naïve prior to vaccination (p < 0.001 for both). Positive SARS-COV-2 IgG in saliva was concordant with prior infection (Anti N, S, RBD) and vaccination (Anti S, RBD) and remained above positivity threshold for up to 9 months from infection. Salivary sampling is a non-invasive method of tracking immunity and differentiating between prior infection and vaccination to inform the need for boosters in LTC residents and staff.

Relação entre Idade e Imunidade para a COVID-19 em Profissionais de Saúde

Introduction The initiation of vaccination against Covid-19 raises some questions about the effectiveness, safety, durability of protection and the need for booster doses. The measurement of anti-spike IgG antibodies can help to answer these questions, as well as to reduce the contagion between Health Professionals and patients, ensuring the responsiveness of the National Health Service. Objectives Assess the anti-spike IgG antibody titles in vaccinated healthcare professionals at three and six months after full vaccination and how they vary with age. Methodology Anti-spike IgG antibodies against SARS-CoV2 were measured in a group of 923 health professionals from a Local Health Unit at three and six months after vaccination with the COMIRNATY® vaccine. The serological test used was the fully automated chemiluminescent immunoassay (Abbott). Epidemiological data was collected, such as Age, Gender and Professional Category, and it was determined whether there was a relationship between antibody titles and age. Results Of the 923 participants, the majority were women (81.4%), and the mean age was 45.51 years. Antibody titles averaged 6452.61 AU/mL at three months and 2011.17AU/mL at six months, with a drop of 68.84% from three to six months. From the results obtained, it can be noted that antibody values vary with age: the older the age, the lower the number of antibodies produced, and from three to six months this association is stronger, that is, older people produce fewer antibodies, and they lose them intensely over time. Discussion/Conclusion The measurement of IgG anti-spike antibodies cannot be seen as a unique measure of vaccine efficacy, there is also an important component of humoral immunity that we still do not know for sure the true importance. Antibody dosing may provide relevant information about efficacy, the need for vaccine booster, identification of risk groups and contributing to disease prevention in Health Professionals. This study allows us to identify that most people responded well to vaccination, but that the antibodies drop sharply from three to six months. It also makes it possible to establish a relationship, albeit tenuous, between age and antibody titles, reinforcing the idea of boosting vaccination in older people. Keywords: Covid-19, Vaccine, Immunity, Antibodies, Age, Occupational Health.

22. An Innovative Approach to Examining the Waning of Vaccine Effectiveness Using Automated Healthcare Data

BackgroundWe conducted a large real-world study of the long-term vaccine effectiveness (VE) of the live attenuated zoster vaccine (Zostavax; ZVL). Using an innovative approach with automated observational data we measured VE for incident herpes zoster (HZ) and severe HZ outcomes including post-herpetic neuralgia (PHN), herpes zoster ophthalmicus (HZO), and hospitalized HZ. This approach could be useful in long-term effectiveness studies of other vaccines.MethodsWe assessed VE against HZ, PHN, HZO and hospitalized HZ for up to 10+ years after vaccination at Kaiser Permanente Northern California. We identified incident cases using diagnoses, laboratory tests and prescriptions, and validated a sample by chart review. For each outcome, we used a Cox regression model with a calendar timeline to estimate VE in relation to year since vaccination. The model for HZ included 11 time-varying vaccination status indicators to denote -- at each timepoint during follow-up -- either the number of years since ZVL vaccination (30 days to < 1 year, 1 to < 2 years, . . ., and 10+ years) or that the individual is unvaccinated (reference group). Analyses were adjusted for demographics and time-varying measures of immune compromise status, healthcare use and comorbidities. ResultsFrom 2007-2018, 1.5 million people contributed to analyses; 507,000 (34%) were vaccinated. During 9 million person-years of follow-up, we observed 75,135 HZ cases, including 4,982 (7%) with PHN, 4,418 (6%) with HZO, and 555 (< 1%) who were hospitalized. VE for HZ was 67% (95% Confidence Interval [CI]: 65-69%) in the first year after vaccination, waned to 50% (CI: 47-52%) in the second year after vaccination, and then waned more gradually to 15% (CI: 5-24%) by 10+ years after vaccination. Initial VE was higher against PHN (83%; CI: 78-87%) and hospitalized HZ (89%; CI: 67-97%) with less waning observed over time (42% by Year 8 for PHN and 53% in Years 5 to < 8 for hospitalized HZ). VE against HZO was 71% in Year 1 and waned to 29% in Years 5 to < 8. ConclusionOur large population, long follow-up and innovative methods let us estimate VE against HZ, PHN, HZO and hospitalized HZ for 10+ years after vaccination. Our approach could help assess waning and need for boosters for vaccines against other agents including COVID-19.Disclosures Morgan Marks, PhD, ScM, Merck & Co Inc. (Employee) Patricia Saddier, MD, PhD, Merck & Co Inc (Employee) Nicola P. Klein, MD, PhD, GlaxoSmithKline (Grant/Research Support)MedImmune (Grant/Research Support)Merck & Co Inc (Grant/Research Support)Pfizer (Grant/Research Support)Protein Sciences (now Sanofi Pasteur) (Grant/Research Support)Sanofi Pasteur (Grant/Research Support)

Protection by vaccination of children against typhoid fever with a Vi-tetanus toxoid conjugate vaccine in urban Bangladesh: a cluster-randomised trial

SummaryBackgroundTyphoid fever remains a major cause of morbidity and mortality in low-income and middle-income countries. Vi-tetanus toxoid conjugate vaccine (Vi-TT) is recommended by WHO for implementation in high-burden countries, but there is little evidence about its ability to protect against clinical typhoid in such settings.MethodsWe did a participant-masked and observer-masked cluster-randomised trial preceded by a safety pilot phase in an urban endemic setting in Dhaka, Bangladesh. 150 clusters, each with approximately 1350 residents, were randomly assigned (1:1) to either Vi-TT or SA 14-14-2 Japanese encephalitis (JE) vaccine. Children aged 9 months to less than 16 years were invited via parent or guardian to receive a single, parenteral dose of vaccine according to their cluster of residence. The study population was followed for an average of 17·1 months. Total and overall protection by Vi-TT against blood culture-confirmed typhoid were the primary endpoints assessed in the intention-to-treat population of vaccinees or all residents in the clusters. A subset of approximately 4800 participants was assessed with active surveillance for adverse events. The trial is registered at www.isrctn.com, ISRCTN11643110.Findings41 344 children were vaccinated in April–May, 2018, with another 20 412 children vaccinated at catch-up vaccination campaigns between September and December, 2018, and April and May, 2019. The incidence of typhoid fever (cases per 100 000 person-years) was 635 in JE vaccinees and 96 in Vi-TT vaccinees (total Vi-TT protection 85%; 97·5% CI 76 to 91, p<0·0001). Total vaccine protection was consistent in different age groups, including children vaccinated at ages under 2 years (81%; 95% CI 39 to 94, p=0·0052). The incidence was 213 among all residents in the JE clusters and 93 in the Vi-TT clusters (overall Vi-TT protection 57%; 97·5% CI 43 to 68, p<0·0001). We did not observe significant indirect vaccine protection by Vi-TT (19%; 95% CI −12 to 41, p=0·20). The vaccines were well tolerated, and no serious adverse events judged to be vaccine-related were observed.InterpretationVi-TT provided protection against typhoid fever to children vaccinated between 9 months and less than 16 years. Longer-term follow-up will be needed to assess the duration of protection and the need for booster doses.FundingThe study was funded by the Bill & Melinda Gates Foundation.

Influencers and preference predictors of HPV vaccine uptake among US male and female young adult college students

ObjectiveThe purpose of the study was to assess the knowledge, attitudes and beliefs of male and female college students in Kentucky about HPV associated diseases and vaccines, and to determine which parameters predicted self-reported uptake of HPV vaccination. Materials and methodsA self-selected cross-sectional sample of college students completed an evidence-based online survey. ResultsOf approximately 1200 potential respondents, 585 completed the survey. The average age was 20.6 (SD 3.15) and 78% were female; 84% of the population had had one or more sexual partners. Concern for HPV vaccine safety and potential need for boosters did not significantly deter vaccine uptake. Likewise, knowledge about HPV associated cancers was not predictive of vaccine uptake. On the other hand, parental influence for vaccination was a strong predictor for vaccine uptake (aOR = 5.32, 2.71–13.03), and free vaccine nearly doubled the likelihood of being vaccinated (aOR 1.90, 1.05–3.41). In addition, the strong preference for the respondent's partner to be HPV vaccinated predicted vaccine uptake (aOR = 4.04, 95% CI: 2.31–7.05), but the lack of preference for partner vaccination predicted an unvaccinated self (aOR = 0.50, 0.27–0.93). ConclusionsHPV vaccination has been successful in young adult college students in Kentucky. Young adults prefer their partners to be HPV vaccinated regardless of whether they themselves are vaccinated. Parental influence and free vaccine were positive predictors for vaccine uptake in this population.

Immunogenicity of pulsatile-release PLGA microspheres for single-injection vaccination

The World Health Organization's Expanded Programme on Immunization has led to a dramatic rise in worldwide vaccination rates over the past 40years, yet 19.4 million infants remain underimmunized each year. Many of these infants have received at least one vaccine dose but may remain unprotected because they did not receive subsequent booster doses due to logistical challenges. This study aimed to develop injectable controlled release microparticles with kinetics that mimic common vaccine dosing regimens consisting of large antigen doses administered periodically over the course of months in order to eliminate the need for boosters. Sixteen poly(lactic-co-glycolic acid) (PLGA) microsphere formulations containing bovine serum albumin (BSA) as a model vaccine antigen were screened in vitro to determine their respective release kinetics. Three formulations that exhibited desirable pulsatile release profiles were then selected for studying immunogenicity in mice. Two low-dose microsphere formulations induced peak anti-BSA IgG antibody titers of 13.9±1.3 and 13.7±2.2 log2 compared to 15.5±1.5 log2 for a series of three bolus injections delivered at 0, 4, and 8weeks with an equivalent cumulative dose. Similarly, high-dose formulations induced peak antibody titers that were 16.1±2.1 log2 compared to 17.7±2.2 log2 for controls. All three microparticle formulations studied in vivo induced peak antibody titers that were statistically similar to bolus controls. These results suggest that pulsatile antigen release from polymeric microparticles is a promising approach for single-injection vaccination, which could potentially reduce the logistical burden associated with immunization in the developing world.

Persistence of antibodies 20 y after vaccination with a combined hepatitis A and B vaccine

ABSTRACTVaccination is the most effective and well-tolerated method of conferring long-term protection against hepatitis A and B viruses (HAV; HBV). Long-term studies are required to characterize the duration of protection and need for boosters. Following primary immunization of 150 and 157 healthy adults with 3-doses of combined hepatitis A/hepatitis B vaccine (HAB; Twinrix™, GSK Vaccines, Belgium) at 0-1-6 months in 2 separate studies, we measured vaccine-induced antibody persistence against HAV and HBV annually for 20 y (Study A: NCT01000324; Study B: NCT01037114). Subjects with circulating anti-HAV antibodies < 15 mIU/mL or with anti-hepatitis B surface antigen < 10 mIU/mL were offered an additional monovalent hepatitis A and/or B vaccine dose (Havrix™/Engerix™-B, GSK Vaccines, Belgium). Applying the immunogenicity results from these studies, mathematical modeling predicted long-term persistence. After 20 y, 18 and 25 subjects in studies A and B, respectively, comprised the long-term according-to-protocol cohort for immunogenicity; 100% and 96.0% retained anti-HAV antibodies ≥ 15 mIU/mL, respectively; 94.4% and 92.0% had anti-HBs antibodies ≥ 10 mIU/mL, respectively. Between Years 16–20, 4 subjects who received a challenge dose of monovalent hepatitis A vaccine (N = 2) or hepatitis B vaccine (N = 2), all mounted a strong anamnestic response suggestive of immune memory despite low antibody levels. Mathematical modeling predicts that 40 y after vaccination ≥ 97% vaccinees will maintain anti-HAV ≥ 15 mIU/mL and ≥ 50% vaccinees will retain anti-HBs ≥ 10 mIU/mL. Immunogenicity data confirm that primary immunization with 3-doses of HAB induces persisting anti-HAV and anti-HBs specific antibodies in most adults for up to 20 y; mathematical modeling predicts even longer-term protection.

Vaccinations, response, and controls before and after intestinal transplantation in children.

Vaccination is an effective strategy to decrease infections in transplant recipients. Children after intestinal transplantation carry a high risk of infection due to increased immunosuppression. In a series of 22 children after intestinal transplantation, we studied the vaccination schedules and the antibodies against vaccine-preventable diseases before transplantation, and at one and five yr after transplantation. We reviewed whether the vaccination schedules were complete, and we analysed the factors that may influence serological immunity and the incidence of disease in patients with deficient immunity. All patients completed the recommended vaccination schedules for DTaP-IPV and HBV. After transplantation, the negative antibodies against vaccine-preventable diseases were mostly related to an antirejection therapy: for DTaP-IPV: four of four patients with no antibody had been treated for rejection, for HBV: two of five, HAV: three of four, MMR: three of seven, and VZV: three of four. A post-transplantation varicella infection was followed by acute rejection, with probability for a relationship between both events. We observed 50% of varicella cases in unvaccinated children, highlighting the importance of pretransplant vaccination. Waning immunogenicity mediated by antibodies against vaccine-preventable disease after transplantation indicated a need for boosters. The recommendations should be regularly enforced, as the reliance on routine immunizations schedules is not adequate in immunocompromised patients.

Protection conferred by recombinant turkey herpesvirus avian influenza (rHVT-H5) vaccine in the rearing period in two commercial layer chicken breeds in Egypt

The effectiveness of recombinant turkey herpesvirus avian influenza (A/swan/Hungary/4999/2006(H5N1)) clade 2.2 virus (rHVT-H5) vaccine was evaluated in two layer chicken breeds (White Bovans [WB] and Brown Shaver [BS]). One dose of rHVT-H5 vaccine was administered at day 1 and birds were monitored serologically (haemagglutination inhibition test) and virologically for 19 weeks. Maternally-derived antibody and post-vaccination H5 antibody titres were measured using the Chinese (A/Goose/Guangdong/1/96(H5N1)) HA and the Egyptian (A/chicken/Egypt/128s/2012(H5N1)) HA as antigens. The challenge was conducted at 19 weeks of age and on six experimental groups: Groups I (WB) and II (BS), both vaccinated and challenged; Groups III (WB) and IV (BS), both vaccinated but not challenged; Groups V and VI, unvaccinated specific pathogen free chickens, serving respectively as positive and negative controls. The challenge virus was the clade 2.2.1 highly pathogenic avian influenza H5N1 A/chicken/Egypt/128s/2012 at a dose of 106 median embryo infective dose. For both breeds, complete maternally-derived antibody waning occurred at the age of 4 weeks. The immune response to rHVT-H5 vaccination was detected from the sixth week. The seroconversion rates for both breeds reached 85.7 to 100% in the eighth week of age. Protection levels of 73.3%, 60% and 0% were respectively recorded in Groups I, II and V. No mortalities occurred in the unchallenged groups. Group I showed superior results for all measured post-challenge parameters. In conclusion, a single rHVT-H5 hatchery vaccination conferred a high level of protection for a relatively extended period. This vaccine could be an important tool for future A/H5N1 prevention/control in endemic countries. Further studies on persistence of immunity beyond 19 weeks, need for booster with inactivated vaccines, breed susceptibility and vaccinal response, and transmissibility are recommended.

Response to booster doses of hepatitis B vaccine among young adults who had received neonatal vaccination.

BackgroundNewborns who have received hepatitis B immunization in 1980s are now young adults joining healthcare disciplines. The need for booster, pre- and post-booster checks becomes a practical question.AimsThe aim of this study is to refine the HBV vaccination policy for newly admitted students in the future.MethodsA prospective study on medical and nursing school entrants to evaluate hepatitis B serostatus and the response to booster doses among young adults.FindingsAmong 212 students, 17–23-year-old, born after adoption of neonatal immunization, 2 (0.9%) were HBsAg positive, 40 (18.9%) were anti-HBs positive. At 1 month after a single-dose booster for anti-HBs-negative students, 14.5% had anti-HBs <10 mIU/mL, 29.0% and 56.5% were 10–100 and >100 mIU/mL, respectively. The anti-HBs levels were significantly higher for females than males (mean [SD]: 431 [418] vs. 246 [339] mIU/mL, P = 0.047). At 2–4 month after the third booster dose, 97.1% had anti-HBs >100 mIU/mL and 2.9% had 10–100 mIU/mL.ConclusionsPre-booster check is still worthwhile to identify carriers among newly recruited healthcare workers born after adoption of neonatal immunization. A 3-dose booster, rather than a single dose, is required for the majority to achieve an anti-HBs level >100 mIU/mL, as memory immunity has declined in a substantial proportion of individuals. Cost-effectiveness of post-booster check for anti-HBs is low and should be further evaluated based on contextual specific utilization of results.

Booster Vaccination: The Role of Reduced Antigen Content Vaccines as a Preschool Booster

The need for boosters for tetanus, diphtheria, pertussis, and polio, starting from preschool age, is related to the waning immune protection conferred by vaccination, the elimination/reduction of natural boosters due to large-scale immunization programs, and the possibility of reintroduction of wild agents from endemic areas. Taking into account the relevance of safety/tolerability in the compliance with vaccination among the population, it have been assessed whether today enough scientific evidences are available to support the use of dTap-IPV booster in preschool age. The review of the literature was conducted using the PubMed search engine. A total of 41 works has been selected; besides, the documentation produced by the World Health Organization, the European Centre for Disease Control, and the Italian Ministry of Health has been consulted. Many recent papers confirm the opportunity to use a low antigenic dose vaccine starting from 4 to 6 years of age. There is also evidence that 10 years after immunization the rate of seroprotected subjects against diphtheria does not differ significantly between those vaccinated with paediatric dose (DTaP) or reduced dose (dTaP or dTap) product. The dTpa vaccine is highly immunogenic for diphtheria toxoids regardless of prior vaccination history (2 + 1 and 3 + 1 schedules).

No need for booster for yellow fever vax

No need for booster for yellow fever vax