The complementary roles of Phase 3 trials and post-licensure surveillance in the evaluation of new vaccines

The impact of EV71 vaccination program on hand, foot and mouth disease in Zhejiang Province, China: A negative control study

Objective

To estimate the potential causal impact of Enterovirus A71 (EV71) vaccination program on the reduction of EV71-infected hand, foot, and mouth disease (HFMD) in Zhejiang Province.

Methods

We utilized the longitudinal surveillance dataset of HFMD and EV71 vaccination in Zhejiang Province during 2010-2019. We estimated vaccine efficacy using a Bayesian structured time series (BSTS) model, and employed a negative control outcome (NCO) model to detect unmeasured confounding and reveal potential causal association.

Results

We estimated that 20,132 EV71 cases (95% CI: 16,733, 23,532) were prevented by vaccination program during 2017-2019, corresponding to a reduction of 29% (95% CI: 24%, 34%). The effectiveness of vaccination increased annually, with reductions of 11% (95% CI: 6%, 16%) in 2017 and 66% (95% CI: 61%, 71%) in 2019. Children under 5 years old obtained greater benefits compared to those over 5 years. Cities with higher vaccination coverage experienced a sharper EV71 reduction compared to those with lower coverage. The NCO model detected no confounding factors in the association between vaccination and EV71 cases reduction.

Conclusions

This study suggested a potential causal effect of the EV71 vaccination, highlighting the importance of achieving higher vaccine coverage to control the HFMD.

Established and new rotavirus vaccines: a comprehensive review for healthcare professionals

Robust scientific evidence related to two rotavirus (RV) vaccines available worldwide demonstrates their significant impact on RV disease burden. Improving RV vaccination coverage may result in better RV disease control. To make RV vaccination accessible to all eligible children worldwide and improve vaccine effectiveness in high-mortality settings, research into new RV vaccines continues. Although current and in-development RV vaccines differ in vaccine design, their common goal is the reduction of RV disease risk in children <5 years old for whom disease burden is the most significant. Given the range of RV vaccines available, informed decision-making is essential regarding the choice of vaccine for immunization. This review aims to describe the landscape of current and new RV vaccines, providing context for the assessment of their similarities and differences. As data for new vaccines are limited, future investigations will be required to evaluate their performance/added value in a real-world setting.

Assessment of Herpes Zoster Risk Among Recipients of COVID-19 Vaccine

Importance

Herpes zoster infection after COVID-19 vaccination has been reported in numerous case studies. It is not known whether these cases represent increased reporting or a true increase in risk.

Objective

To assess whether COVID-19 vaccination is associated with an increased risk of herpes zoster infection.

Design, Setting, and Participants

This cohort study used a self-controlled risk interval (SCRI) design to compare the risk of herpes zoster in a risk interval of 30 days after COVID-19 vaccination or up to the date of the second vaccine dose with a control interval remote from COVID-19 vaccination (defined as 60-90 days after the last recorded vaccination date for each individual, allowing for a 30-day washout period between control and risk intervals). A supplemental cohort analysis was used to compare the risk of herpes zoster after COVID-19 vaccination with the risk of herpes zoster after influenza vaccination among 2 historical cohorts who received an influenza vaccine in the prepandemic period (January 1, 2018, to December 31, 2019) or the early pandemic period (March 1, 2020, to November 30, 2020). Data were obtained from Optum Labs Data Warehouse, a US national deidentified claims-based database. A total of 2 039 854 individuals who received any dose of a COVID-19 vaccine with emergency use authorization (BNT162b2 [Pfizer-BioNTech], mRNA-1273 [Moderna], or Ad26.COV2.S [Johnson & Johnson]) from December 11, 2020, through June 30, 2021, were eligible for inclusion. Individuals included in the SCRI analysis were a subset of the COVID-19-vaccinated cohort who had herpes zoster during either a risk or control interval.

Exposures

Any dose of a COVID-19 vaccine.

Main Outcomes and Measures

Incident herpes zoster, defined by International Statistical Classification of Diseases and Related Health Problems, Tenth Revision codes and a prescription of a new antiviral medication or a dose increase in antiviral medication within 5 days of diagnosis.

Results

Among 2 039 854 individuals who received any dose of a COVID-19 vaccine during the study period, the mean (SD) age was 43.2 (16.3) years; 1 031 149 individuals (50.6%) were female, and 1 344 318 (65.9%) were White. Of those, 1451 patients (mean [SD] age, 51.6 [12.6] years; 845 [58.2%] female) with a herpes zoster diagnosis were included in the primary SCRI analysis. In the SCRI analysis, COVID-19 vaccination was not associated with an increased risk of herpes zoster after adjustment (incidence rate ratio, 0.91; 95% CI, 0.82-1.01; P = .08). In the supplementary cohort analysis, COVID-19 vaccination was not associated with a higher risk of herpes zoster compared with influenza vaccination in the prepandemic period (first dose of COVID-19 vaccine: hazard ratio [HR], 0.78 [95% CI, 0.70-0.86; P < .001]; second dose of COVID-19 vaccine: HR, 0.79 [95% CI, 0.71-0.88; P < .001]) or the early pandemic period (first dose of COVID-19 vaccine: HR, 0.89 [95% CI, 0.80-1.00; P = .05]; second dose: HR, 0.91 [95% CI, 0.81-1.02; P = .09]).

Conclusions and Relevance

In this study, there was no association found between COVID-19 vaccination and an increased risk of herpes zoster infection, which may help to address concerns about the safety profile of the COVID-19 vaccines among patients and clinicians.

Background incidence rates of adverse events of special interest related to COVID-19 vaccines in Ontario, Canada, 2015 to 2020, to inform COVID-19 vaccine safety surveillance

Background

Background incidence rates are critical in pharmacovigilance to facilitate identification of vaccine safety signals. We estimated background incidence rates of 11 adverse events of special interest related to COVID-19 vaccines in Ontario, Canada.

Methods

We conducted a population-based retrospective observational study using linked health administrative databases for hospitalizations and emergency department visits among Ontario residents. We estimated incidence rates of Bell’s palsy, idiopathic thrombocytopenia, febrile convulsions, acute disseminated encephalomyelitis, myocarditis, pericarditis, Kawasaki disease, Guillain-Barré syndrome, transverse myelitis, acute myocardial infarction, and anaphylaxis during five pre-pandemic years (2015–2019) and 2020.

Results

The average annual population was 14 million across all age groups with 51% female. The pre-pandemic mean annual rates per 100,000 population during 2015–2019 were 191 for acute myocardial infarction, 43.9 for idiopathic thrombocytopenia, 28.8 for anaphylaxis, 27.8 for Bell’s palsy, 25.0 for febrile convulsions, 22.8 for acute disseminated encephalomyelitis, 11.3 for myocarditis/pericarditis, 8.7 for pericarditis, 2.9 for myocarditis, 2.0 for Kawasaki disease, 1.9 for Guillain-Barré syndrome, and 1.7 for transverse myelitis. Females had higher rates of acute disseminated encephalomyelitis, transverse myelitis and anaphylaxis while males had higher rates of myocarditis, pericarditis, and Guillain-Barré syndrome. Bell’s palsy, acute disseminated encephalomyelitis, and Guillain-Barré syndrome increased with age. The mean rates of myocarditis and/or pericarditis increased with age up to 79 years; males had higher rates than females: from 12 to 59 years for myocarditis and ≥12 years for pericarditis. Febrile convulsions and Kawasaki disease were predominantly childhood diseases and generally decreased with age.

Conclusions

Our estimated background rates will permit estimating numbers of expected events for these conditions and facilitate detection of potential safety signals following COVID-19 vaccination.

Waning effectiveness of CoronaVac in real life: A retrospective cohort study in health care workers

Background

Real-world studies showed varying levels of effectiveness of CoronaVac vaccine against COVID-19 disease. This study aimed to assess the association between the vaccination with CoronaVac and the COVID-19 infections among the health care workers in a university hospital and to determine the vaccine effectiveness against COVID-19 in a period when alpha variant was dominant.

Methods

This retrospective cohort study was conducted in a university hospital in Istanbul, Turkey employs 4067 health care workers. The follow-up period was defined as starting 14 days after receiving the second dose for fully vaccinated group. Health care workers were censored when have a positive PCR test result or at the end of the study. Unvaccinated health care workers were censored if they receive any COVID-19 vaccine doses. The incidence rate ratio and Cox regression were used to estimate the unadjusted and adjusted effectiveness of the vaccine.

Findings: Seventy-one percent of the health care workers were fully vaccinated whereas 29% percent did not receive any doses. The incidence rate of SARS-CoV-2 infection was 133.7 vs 70.7 per 100.000 person-days in the unvaccinated and fully vaccinated groups, respectively. The unadjusted effectiveness against COVID-19 infection was 47% (95% CI 31–59%) whereas adjusted effectiveness was 39% (95% CI 20–64%).

Interpretation: This real life study conducted in health care workers demonstrated that the effectiveness of two doses of the CoronaVac vaccine (39%) was lower than that determined in clinical trials. Due to reduce in protection over time or against variants, booster doses may be needed.

Independent risk factors of COVID-19 pneumonia in vaccinated Mexican adults

Objectives

To evaluate host factors associated with the risk of coronavirus disease 2019 (COVID-19) pneumonia in vaccinated adults.

Methods

A cohort study was conducted in Mexico, and data from 1607 adults with confirmed illness, with a positive history of COVID-19 vaccination, were analyzed. Risk ratios (RR) and 95% confidence intervals (CI) were computed as a measure of the significance of the associations between putative risk factors and the prevalence of COVID-19 pneumonia in vaccinated subjects.

Results

The overall risk of pneumonia was 1.98 per 1000 person-days. In the multiple regression analysis, older subjects, those with a history of smoking (current), obesity, and type 2 diabetes mellitus were at increased risk of pneumonia.

Conclusions

Our results suggest that the effectiveness of COVID-19 vaccines may be reduced in a subset of adults who are older aged, smokers, obese, or have type 2 diabetes mellitus.

Impact of SARS-CoV-2 Delta variant on incubation, transmission settings and vaccine effectiveness: Results from a nationwide case-control study in France

BACKGROUND

We aimed to assess the settings and activities associated with SARS-CoV-2 infection in the context of B.1.617.2 (Delta) variant circulation in France, as well as the protection against symptomatic Delta infection.

METHODS

In this nationwide case-control study, cases were SARS-CoV-2 infected adults recruited between 23 May and 13 August 2021. Controls were non-infected adults from a national representative panel matched to cases by age, sex, region, population density and calendar week. Participants completed an online questionnaire and multivariable logistic regression analysis was used to determine the association between acute SARS-CoV-2 infection and recent activity-related exposures, past history of SARS-CoV-2 infection, and COVID-19 vaccination.

FINDINGS

We did not find any differences in the settings and activities associated with Delta versus non-Delta infections and grouped them for subsequent analyses. In multivariable analysis involving 12634 cases (8644 Delta and 3990 non-Delta) and 5560 controls, we found individuals under 40 years and attending bars (aOR:1.9; 95%CI:1.6-2.2) or parties (aOR:3.4; 95%CI:2.8-4.2) to be at increased risk of infection. In those aged 40 years and older, having children attend daycare (aOR:1.9; 95%CI:1.1-3.3), kindergarten (aOR:1.6; 95%CI:1.2-2.1), primary school (aOR:1.4; 95%CI:1.2-1.6) or middle school (aOR:1.3; 95%CI:1.2-1.6) were associated with increased risk of infection. We found strong protection against symptomatic Delta infection for those with prior infection whether it was recent (2-6 months) (95%; 95%CI:90-97) or associated with one dose (85%; 95%CI:78-90) or two doses of mRNA vaccine (96%; 95%CI:87-99). For those without past infection, protection was lower with two doses of mRNA vaccine (67%; 95%CI:63-71).

INTERPRETATION

In line with other observational studies, we find reduced vaccine effectiveness against symptomatic Delta infections. The settings and activities at increased risk of infection indicate where efforts to reinforce individual and public health measures need to be concentrated.

Vaccine Procurement: A Conceptual Framework Based on Literature Review

Ensuring timely access to affordable vaccines has been acknowledged as a global public health priority, as also recently testified by the debate sparked during the COVID-19 pandemic. Effective vaccine procurement strategies are essential to reach this goal. Nevertheless, this is still a neglected research topic. A narrative literature review on vaccine procurement was conducted, by retrieving articles from four academic databases (PubMed/MEDLINE, Scopus, Embase, WebOfScience), 'grey' literature reports, and institutional websites. The aim was to clarify key concepts and definitions relating to vaccine procurement, describe main vaccine procurement methods, and identify knowledge gaps and future perspectives. A theoretical conceptual framework was developed of the key factors involved in vaccine procurement, which include quality and safety of the product, forecasting and budgeting, procurement legislation, financial sustainability, and plurality of manufacture, contracting, investment in training, storage and service delivery, monitoring and evaluation. This information can be useful to support policymakers during planning, implementation, and evaluation of regional and national vaccine procurement strategies and policies.

Effectiveness of an Inactivated SARS-CoV-2 Vaccine in Chile

BACKGROUND

Mass vaccination campaigns to prevent coronavirus disease 2019 (Covid-19) are occurring in many countries; estimates of vaccine effectiveness are urgently needed to support decision making. A countrywide mass vaccination campaign with the use of an inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine (CoronaVac) was conducted in Chile starting on February 2, 2021.

METHODS

We used a prospective national cohort, including participants 16 years of age or older who were affiliated with the public national health care system, to assess the effectiveness of the inactivated SARS-CoV-2 vaccine with regard to preventing Covid-19 and related hospitalization, admission to the intensive care unit (ICU), and death. We estimated hazard ratios using the extension of the Cox proportional-hazards model, accounting for time-varying vaccination status. We estimated the change in the hazard ratio associated with partial immunization (≥14 days after receipt of the first dose and before receipt of the second dose) and full immunization (≥14 days after receipt of the second dose). Vaccine effectiveness was estimated with adjustment for individual demographic and clinical characteristics.

RESULTS

The study was conducted from February 2 through May 1, 2021, and the cohort included approximately 10.2 million persons. Among persons who were fully immunized, the adjusted vaccine effectiveness was 65.9% (95% confidence interval [CI], 65.2 to 66.6) for the prevention of Covid-19 and 87.5% (95% CI, 86.7 to 88.2) for the prevention of hospitalization, 90.3% (95% CI, 89.1 to 91.4) for the prevention of ICU admission, and 86.3% (95% CI, 84.5 to 87.9) for the prevention of Covid-19-related death.

CONCLUSIONS

Our results suggest that the inactivated SARS-CoV-2 vaccine effectively prevented Covid-19, including severe disease and death, a finding that is consistent with results of phase 2 trials of the vaccine. (Funded by Agencia Nacional de Investigación y Desarrollo and others.).

Impact of original, B.1.1.7, and B.1.351/P.1 SARS-CoV-2 lineages on vaccine effectiveness of two doses of COVID-19 mRNA vaccines: Results from a nationwide case-control study in France

Background

We aimed to assess the effectiveness of two doses of mRNA COVID-19 vaccines against COVID-19 with the original virus and other lineages circulating in France.

Methods

In this nationwide case-control study, cases were SARS-CoV-2 infected adults with onset of symptoms between 14 February and 3 May 2021. Controls were non-infected adults from a national representative panel matched to cases by age, sex, region, population density and calendar week. Participants completed an online questionnaire on recent activity-related exposures and vaccination history. Information about the infecting virus was based on a screening RT-PCR for either B.1.1.7 or B.1.351/P.1 variants.

Findings

Included in our analysis were 7 288 adults infected with the original SARS-CoV-2 virus, 31 313 with the B.1.1.7 lineage, 2 550 with B.1.351/P1 lineages, and 3 644 controls. In multivariable analysis, the vaccine effectiveness (95% confidence interval) seven days after the second dose of mRNA vaccine was estimated at 88% (81-92), 86% (81-90) and 77% (63-86) against COVID-19 with the original virus, the B.1.1.7 lineage, and the B.1.351/P.1 lineages, respectively. Recent (2 to 6 months) history of virologically confirmed SARS-CoV-2 infection was found to be 83% (76-88), 88% (85-91) and 83% (71-90) protective against COVID-19 with the original virus, the B.1.1.7 lineage, and the B.1.351/P.1 lineages, respectively; and more distant (> 6 months) infections were 76% (54-87), 84% (75-90), and 74% (41-89) protective against COVID-19 with the original virus, the B.1.1.7 lineage, and the B.1.351/P.1 lineages, respectively.

Interpretation

In real-life settings, two doses of mRNA vaccines proved to be effective against COVID-19 with the original virus, B.1.1.7 lineage and B.1.351/P.1 lineages.

Funding

Institut Pasteur, Research & Action Emerging Infectious Diseases (REACTing), Fondation de France (Alliance “Tous unis contre le virus”).

Interim findings from first-dose mass COVID-19 vaccination roll-out and COVID-19 hospital admissions in Scotland: a national prospective cohort study

BACKGROUND

The BNT162b2 mRNA (Pfizer-BioNTech) and ChAdOx1 nCoV-19 (Oxford-AstraZeneca) COVID-19 vaccines have shown high efficacy against disease in phase 3 clinical trials and are now being used in national vaccination programmes in the UK and several other countries. Studying the real-world effects of these vaccines is an urgent requirement. The aim of our study was to investigate the association between the mass roll-out of the first doses of these COVID-19 vaccines and hospital admissions for COVID-19.

METHODS

We did a prospective cohort study using the Early Pandemic Evaluation and Enhanced Surveillance of COVID-19-EAVE II-database comprising linked vaccination, primary care, real-time reverse transcription-PCR testing, and hospital admission patient records for 5·4 million people in Scotland (about 99% of the population) registered at 940 general practices. Individuals who had previously tested positive were excluded from the analysis. A time-dependent Cox model and Poisson regression models with inverse propensity weights were fitted to estimate effectiveness against COVID-19 hospital admission (defined as 1-adjusted rate ratio) following the first dose of vaccine.

FINDINGS

Between Dec 8, 2020, and Feb 22, 2021, a total of 1 331 993 people were vaccinated over the study period. The mean age of those vaccinated was 65·0 years (SD 16·2). The first dose of the BNT162b2 mRNA vaccine was associated with a vaccine effect of 91% (95% CI 85-94) for reduced COVID-19 hospital admission at 28-34 days post-vaccination. Vaccine effect at the same time interval for the ChAdOx1 vaccine was 88% (95% CI 75-94). Results of combined vaccine effects against hospital admission due to COVID-19 were similar when restricting the analysis to those aged 80 years and older (83%, 95% CI 72-89 at 28-34 days post-vaccination).

INTERPRETATION

Mass roll-out of the first doses of the BNT162b2 mRNA and ChAdOx1 vaccines was associated with substantial reductions in the risk of hospital admission due to COVID-19 in Scotland. There remains the possibility that some of the observed effects might have been due to residual confounding.

FUNDING

UK Research and Innovation (Medical Research Council), Research and Innovation Industrial Strategy Challenge Fund, Health Data Research UK.

Interim findings from first-dose mass COVID-19 vaccination roll-out and COVID-19 hospital admissions in Scotland: a national prospective cohort study

BACKGROUND

The BNT162b2 mRNA (Pfizer-BioNTech) and ChAdOx1 nCoV-19 (Oxford-AstraZeneca) COVID-19 vaccines have shown high efficacy against disease in phase 3 clinical trials and are now being used in national vaccination programmes in the UK and several other countries. Studying the real-world effects of these vaccines is an urgent requirement. The aim of our study was to investigate the association between the mass roll-out of the first doses of these COVID-19 vaccines and hospital admissions for COVID-19.

METHODS

We did a prospective cohort study using the Early Pandemic Evaluation and Enhanced Surveillance of COVID-19-EAVE II-database comprising linked vaccination, primary care, real-time reverse transcription-PCR testing, and hospital admission patient records for 5·4 million people in Scotland (about 99% of the population) registered at 940 general practices. Individuals who had previously tested positive were excluded from the analysis. A time-dependent Cox model and Poisson regression models with inverse propensity weights were fitted to estimate effectiveness against COVID-19 hospital admission (defined as 1-adjusted rate ratio) following the first dose of vaccine.

FINDINGS

Between Dec 8, 2020, and Feb 22, 2021, a total of 1 331 993 people were vaccinated over the study period. The mean age of those vaccinated was 65·0 years (SD 16·2). The first dose of the BNT162b2 mRNA vaccine was associated with a vaccine effect of 91% (95% CI 85-94) for reduced COVID-19 hospital admission at 28-34 days post-vaccination. Vaccine effect at the same time interval for the ChAdOx1 vaccine was 88% (95% CI 75-94). Results of combined vaccine effects against hospital admission due to COVID-19 were similar when restricting the analysis to those aged 80 years and older (83%, 95% CI 72-89 at 28-34 days post-vaccination).

INTERPRETATION

Mass roll-out of the first doses of the BNT162b2 mRNA and ChAdOx1 vaccines was associated with substantial reductions in the risk of hospital admission due to COVID-19 in Scotland. There remains the possibility that some of the observed effects might have been due to residual confounding.

FUNDING

UK Research and Innovation (Medical Research Council), Research and Innovation Industrial Strategy Challenge Fund, Health Data Research UK.

Pertussis vaccine effectiveness and duration of protection - A systematic review and meta-analysis

A comprehensive review of observational pertussis vaccine effectiveness (VE) studies is needed to update gaps from previous reviews. We conducted a systematic review of VE and duration of protection studies for the whole-cell (wP) and acellular (aP) pertussis vaccines and conducted a formal meta-analysis using random effects models. Evidence continues to suggest that receipt of any pertussis vaccine confers protection in the short-term against disease although this protection wanes rapidly for aP vaccine. We detected significant heterogeneity in pooled estimates due, in part, to factors such as bias and confounding which may be mitigated by study design. Our review of possible sources of heterogeneity may help interpretation of other VE studies and aid design decisions in future pertussis VE research.

Pregnant women & vaccines against emerging epidemic threats: Ethics guidance for preparedness, research, and response

Zika virus, influenza, and Ebola have called attention to the ways in which infectious disease outbreaks can severely - and at times uniquely - affect the health interests of pregnant women and their offspring. These examples also highlight the critical need to proactively consider pregnant women and their offspring in vaccine research and response efforts to combat emerging and re-emerging infectious diseases. Historically, pregnant women and their offspring have been largely excluded from research agendas and investment strategies for vaccines against epidemic threats, which in turn can lead to exclusion from future vaccine campaigns amidst outbreaks. This state of affairs is profoundly unjust to pregnant women and their offspring, and deeply problematic from the standpoint of public health. To ensure that the needs of pregnant women and their offspring are fairly addressed, new approaches to public health preparedness, vaccine research and development, and vaccine delivery are required. This Guidance offers 22 concrete recommendations that provide a roadmap for the ethically responsible, socially just, and respectful inclusion of the interests of pregnant women in the development and deployment of vaccines against emerging pathogens. The Guidance was developed by the Pregnancy Research Ethics for Vaccines, Epidemics, and New Technologies (PREVENT) Working Group - a multidisciplinary, international team of 17 experts specializing in bioethics, maternal immunization, maternal-fetal medicine, obstetrics, pediatrics, philosophy, public health, and vaccine research and policy - in consultation with a variety of external experts and stakeholders.

Systematic literature review of the impact and effectiveness of monovalent meningococcal C conjugated vaccines when used in routine immunization programs

BACKGROUND

Monovalent meningococcal C conjugate vaccine (MCCV) was introduced into the routine immunization program in many countries in Europe and worldwide following the emergence of meningococcal serogroup C (MenC) in the late 1990s. This systematic literature review summarizes the immediate and long-term impact and effectiveness of the different MCCV vaccination schedules and strategies employed.

METHODS

We conducted a systematic literature search for peer-reviewed, scientific publications in the databases of MEDLINE (via PubMed), LILACS, and SCIELO. We included studies from countries where MCCV have been introduced in routine vaccination programs and studies providing the impact and effectiveness of MCCV published between 1st January 2001 and 31st October 2017.

RESULTS

Forty studies were included in the review; 30 studies reporting impact and 17 reporting effectiveness covering 9 countries (UK, Spain, Italy, Canada, Brazil, Australia, Belgium, Germany and the Netherlands). Following MCCV introduction, significant and immediate reduction of MenC incidence was consistently observed in vaccine eligible ages in all countries with high vaccine uptake. The reduction in non-vaccine eligible ages (especially population > 65 years) through herd protection was generally observed 3-4 years following introduction. Vaccine effectiveness (VE) was mostly assessed through screening methods and ranged from 38 to 100%. The VE was generally highest during the first year after vaccination and waned over time. The VE was better maintained in countries employing catch-up campaigns in older children and adolescents, compared to routine infant only schedules.

CONCLUSIONS

MCCV were highly effective, showing a substantial and sustained decrease in MenC invasive meningococcal disease. The epidemiology of meningococcal disease is in constant transition, and some vaccination programs now include adolescents and higher valent vaccines due to the recent increase in cases caused by serogroups not covered by MCCV. Continuous monitoring of meningococcal disease is essential to understand disease evolution in the setting of different vaccination programs.

Letter to the editor concerning the article 'Association between rotavirus vaccination and risk of intussusception among neonates and infants: a systematic review and meta-analysis' (JAMA Netw Open. 2019;2(10):e1912458)

A recent meta-analysis investigating the association between intussusception (IS) and rotavirus (RV) vaccination demonstrated an absence of risk up to 2 years after vaccination. Meta-analyses including only randomized clinical trials are inadequate to identify a potential increased risk of rare adverse events such as IS. The study conducted failed to discuss relevant limitations. Additionally, the safety profiles of newer RV vaccines, evaluated in clinical studies with limited sample size, were considered comparable with that of the well-established and widely used RV vaccines, RotaTeq and Rotarix. We, therefore, re-emphasize that extensive and updated evidence from post-marketing surveillance indicates a slight increased risk of IS, mostly within 7 days of RV vaccination, with a benefit/risk profile assessment in favor of RV vaccination.

Key steps in vaccine development

OBJECTIVE

The goal of a vaccine is to prime the immune response so the immune memory can facilitate a rapid response to adequately control the pathogen on natural infection and prevent disease manifestation. This article reviews the main elements that provide for the development of safe and effective vaccines.

DATA SOURCES

Literature covering target pathogen epidemiology, the key aspects of the functioning immune response underwriting target antigen selection, optimal vaccine formulation, preclinical and clinical trial studies necessary to deliver safe and efficacious immunization.

STUDY SELECTIONS

Whole live, inactivated, attenuated, or partial fractionated organism-based vaccines are discussed in respect of the balance of reactogenicity and immunogenicity. The use of adjuvants to compensate for reduced immunogenicity is described. The requirements from preclinical studies, including establishing a proof of principle in animal models, the design of clinical trials with healthy volunteers that lead to licensure and beyond are reviewed.

RESULTS

The 3 vaccine development phases, preclinical, clinical, and post-licensure, integrate the requirements to ensure safety, immunogenicity, and efficacy in the final licensed product. Continuing monitoring of efficacy and safety in the immunized populations is essential to sustain confidence in vaccination programs.

CONCLUSION

In an era of increasing vaccine hesitancy, the need for a better and widespread understanding of how immunization acts to counteract the continuing and changing risks from the pathogenic world is required. This demands a societal responsibility for obligate education on the benefits of vaccination, which as a medical intervention has saved more lives than any other procedure.

Use of Real-world Evidence to Evaluate the Effectiveness of Herpes Zoster Vaccine

This article reviews the use of real-world evidence (RWE) from observational studies to evaluate herpes zoster vaccine effectiveness and complement clinical trial data that have known limitations. The use of RWE with appropriate study designs and cautious interpretation can be informative in decision-making. Understanding the advantages and limitations of studies yielding RWE can facilitate the critical evaluation of findings from different studies. This is a timely issue, as regulatory agencies are considering how RWE can contribute to the assessment of effectiveness in regulatory decision-making.

Risk factors for modified vaccine effectiveness of the live attenuated zoster vaccine among the elderly in England

Background

The United Kingdom introduced routine vaccination with the live-attenuated zoster vaccine for 70 year-olds in 2013, with the vaccine also offered to 79 year-olds as part of a catch-up campaign. In the subsequent years, the catch-up campaign was extended to also include adults aged 78 years. We investigated 14 pre-identified potential risk factors for potential modified vaccine effectiveness.

Methods

This retrospective cohort study in England included subjects born in 1943-1946 (the routine cohort) and in 1934-1937 (the catch-up cohort). We used the Clinical Practice Research Datalink (CPRD) to identify herpes zoster (HZ) cases and the risk factors: age, gender, ethnicity, socio-economic status, asthma, type 2 diabetes, chronic obstructive pulmonary disease, smoking, body mass index, immunosuppression, history of HZ, co-administration with influenza or pneumococcal vaccine. We derived HZ incidence by risk groups, overall vaccine effectiveness (VE) and modified VE expressed as relative differences in VE from Poisson regression models.

Results

Overall VE was 66.8% [95% CI: 62.2; 71.0]. Two out of the 14 investigated risk factors modified the HZ VE. Notably, lower VE was observed in diabetics and in persons with a history of HZ with relative differences in VE of -22·2%, [95% CI: -39·6, -4·5] and -22·5%, [95% CI: -44·9, -0·1].

Conclusions

Live-attenuated zoster vaccine protection against HZ was lower in type 2 diabetics and in subjects with a history of HZ. Contrary to clinical trial results, age did not affect the observed VE. Further study is required to gain insights into why certain risk groups are less protected. Identifying and understanding the effect modifiers of VE is important for future vaccine development as well as vaccine recommendations.

Medicines Regulation in Africa: Current State and Opportunities

Sound regulatory systems are critical for protecting public health against use of medical products which do not meet international standards of quality, safety and efficacy. This review provides a summary of the current status of National Medicines Regulatory Authorities (NMRAs) in Africa, and various initiatives that have been established to improve their performance. All countries in Africa (except Sahrawi Republic), have NMRAs but their organizational set-up and functionality is variable. Some are located within Ministries of Health and others are semi-autonomous. There is progressive improvement in regulatory capacity, particularly in quality control and post-marketing surveillance, pharmacovigilance and clinical trials oversight. The African Vaccines Regulatory Forum, African Medicines Regulatory Harmonization Initiative, Network of Official Medicines Control Laboratories and WHO Prequalification Scheme have helped countries strengthen their regulatory capacities. The potential establishment of the African Medicines Agency (AMA) in 2018 is an opportunity to improve NMRAs’ capacity in Africa.

Introduction to RNA Vaccines

RNA vaccines are attractive, because they exhibit characteristics of subunit vaccines and live-attenuated vectors, including flexible production and induction of both humoral and cellular immunity. While human proof-of-concept for RNA vaccines is still pending, the nascent field of RNA therapeutics has already attracted substantial industry and government funding as well as record investments of private venture capital. Most recently, the WHO acknowledged messenger RNA (mRNA) as a new therapeutic class. In this chapter, we briefly review key developments in RNA vaccines and outline the contents of this volume of Methods in Molecular Biology.

Adverse events following immunization: real causality and myths

INTRODUCTION

To assure the highest safety of immunization programs, detect adverse events following immunization (AEFIs), eliminate concerns, and reduce the risk of low vaccination coverage, authorities in industrialized countries have collected years of reports of suspected AEFIs and have systematically assessed their clinical importance.

AREAS COVERED

In this paper, the methods used to assess vaccine safety and the results obtained by the analysis of reports, studies, and meta-analyses are discussed.

EXPERT OPINION

Severe AEFIs are rare, and all evaluations of safety of vaccines recommended for both children and adults have demonstrated that the advantages of vaccines are always significantly higher than the problems that they cause, and there is no need to modify recommendations. However, the definition of AEFI is dependent on the vaccines themselves, complicating the definition of an AEFI and explaining why doubts and concerns have been raised. Presently, disease epidemiology data collected in healthy people and in subjects with underlying disease, general vaccine coverage, and the vaccination status of subjects with AEFIs are managed by many independent institutions. Only strict co-operation between these institutions will lead to the successful identification of AEFIs and to a reduction of the weight of anti-vaccine arguments.

Safety and tolerability of pneumococcal vaccines in children

INTRODUCTION

A number of pneumococcal vaccines have long been available and have been used to reduce the medical, social, and economic problems associated with Streptococcus pneumoniae-related diseases.

AREAS COVERED

The main purpose of this review was to analyze what has been, until recently, the established doctrine regarding the safety and tolerability of pneumococcal vaccines that have been used in the past and are currently being used in children.

EXPERT OPINION

Pneumococcal vaccines available on the market are all safe and are highly recommended in clinical practice. In children, pneumococcal conjugate vaccines (PCVs) are considered the preparations of choice because of their enhanced immunogenicity and superior ability to impact nasopharyngeal carriage. All PCVs are considered safe because the incidence of severe adverse events (AEs) is marginal. Nonetheless, evidence has emerged from post-marketing surveillance regarding the occurrence of very rare but significant potential AEs following PCV administration. Therefore, post-marketing surveillance should be maintained to confirm the existence of these AEs. Over the next few years, other pneumococcal vaccines will be developed. When these new products are licensed and reach the market, new technologies and innovative epidemiological methods will permit a more rapid and more effective evaluation of AEs.

Can Digital Tools Be Used for Improving Immunization Programs?

In order to successfully control and eliminate vaccine-preventable infectious diseases, an appropriate vaccine coverage has to be achieved and maintained. This task requires a high level of effort as it may be compromised by a number of barriers. Public health agencies have issued specific recommendations to address these barriers and therefore improve immunization programs. In the present review, we characterize issues and challenges of immunization programs for which digital tools are a potential solution. In particular, we explore previously published research on the use of digital tools in the following vaccine-related areas: immunization registries, dose tracking, and decision support systems; vaccine-preventable diseases surveillance; surveillance of adverse events following immunizations; vaccine confidence monitoring; and delivery of information on vaccines to the public. Subsequently, we analyze the limits of the use of digital tools in such contexts and envision future possibilities and challenges.

European decision-maker perspective with regard to influenza prevention policies

Influenza is a public health priority in Europe. The impact of influenza pandemics on public health is very high, but seasonal influenza also constitutes an important burden in terms of hospitalisation and excess deaths. Influenza vaccination is a fundamental pillar of disease prevention. In the absence of a clear decision-making process for vaccination policies, EU institutions have, in recent years, fostered collaboration among Member States. Such collaboration was closer during the 2009 pandemic, which constituted a clear cross-border threat to EU citizens' health. The EU institutions have been supporting national vaccination programmes by providing evidence of the effectiveness and safety of influenza vaccination. Decision 1082/2013 was a major step toward EU collaboration, in that it highlighted the role of pandemic vaccination in the field of preparedness and emergency response, in which concerted action is clearly valuable.

How to best measure the effectiveness of male human papillomavirus vaccine programmes?

In many countries now, vaccination of young adolescent girls with prophylactic human papillomavirus (HPV) vaccines has been rolled out as a public health programme. In countries where coverage has been high, this has led to dramatic reductions in cervical high-grade precancerous lesions, as well as genital warts. A reduction in circulating vaccine-related HPV types has also been demonstrated. With the introduction of gender-neutral approaches incorporating universal vaccination of pre-adolescent boys in some countries, implementation of post-vaccine monitoring will be critical to evaluate the incremental impact of male vaccination. In contrast to cervical screening programmes, population-wide screening for HPV infection or related disease in males is not recommended; hence real-time monitoring of HPV vaccine effectiveness in males will require dedicated surveillance strategies. Monitoring the prevalence of circulating genital HPV types using a sentinel surveillance model could offer a good surrogate marker of early vaccine effectiveness in males. However, such an approach requires careful consideration of the most appropriate anatomical sites from which to collect specimens, the best sampling methods and the most sensitive assays to use. Additionally, in assessing an accurate measure of the impact of HPV vaccination in the male population, the effect of herd protection will need to be assessed, as most male programmes will commence in the setting of established female programmes. This poses an interesting epidemiological challenge.

Methods and challenges in measuring the impact of national pneumococcal and rotavirus vaccine introduction on morbidity and mortality in Malawi

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Evaluation of vaccine impact and effectiveness is critically important but methodologically challenging.

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Challenges include achieving unbiased ascertainment of vaccine status, and non-vaccine-attributable decline in morbidity and mortality.

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Use of multiple sites together with diverse evaluation methods provides more robust evaluation.

Background

Pneumonia and gastroenteritis are leading causes of vaccine-preventable childhood morbidity and mortality. Malawi introduced pneumococcal conjugate and rotavirus vaccines to the immunisation programme in 2011 and 2012, respectively. Evaluating their effectiveness is vital to ensure optimal implementation and justify sustained investment.

Methods/Design

A national evaluation platform was established to determine vaccine effectiveness and impact in Malawi. Impact and effectiveness against vaccine-type invasive pneumococcal disease, radiological pneumonia and rotavirus gastroenteritis are investigated using before-after incidence comparisons and case-control designs, respectively. Mortality is assessed using a prospective population cohort. Cost-effectiveness evaluation is nested within the case-control studies. We describe platform characteristics including strengths and weaknesses for conducting vaccine evaluations.

Discussion

Integrating data from individual level and ecological methods across multiple sites provides comprehensive information for policymakers on programme impact and vaccine effectiveness including changes in serotype/genotype distribution over time. Challenges to robust vaccine evaluation in real-world conditions include: vaccination ascertainment; pre-existing rapid decline in mortality and pneumococcal disease in the context of non-vaccine interventions; and the maintenance of completeness and quality of reporting at scale and over time. In observational non-randomised designs ascertainment of vaccine status may be biased particularly in infants with fatal outcomes. In the context of multiple population level interventions targeting study endpoints attribution of reduced incidence to vaccine impact may be flawed. Providing evidence from several independent but complementary studies will provide the greatest confidence in assigning impact. Welcome declines in disease incidence and in child mortality make accrual of required sample sizes difficult, necessitating large studies to detect the relatively small but potentially significant contribution of vaccines to mortality prevention. Careful evaluation of vaccine effectiveness and impact in such settings is critical to sustaining support for vaccine programmes. Our evaluation platform covers a large population with a high prevalence of HIV and malnutrition and its findings will be relevant to other settings in sub-Saharan Africa.