Adverse events associated with pandemic influenza vaccines: Comparison of the results of a follow-up study with those coming from spontaneous reporting

Cardiovascular Sequelae of the COVID-19 Vaccines

Vaccines against COVID-19 present a key tool in lowering the morbidity, mortality, and transmission of the disease, but they also present a strongly controversial topic. As a result, the adverse effects of the vaccine have been under scrutiny by the public eye. A comprehensive summary of the cardiovascular (CV) adverse effects of COVID-19 vaccines is vital for clinical recognition of rare adverse events, determining the public health implications, and creating a base for future research. In May 2023, a search was conducted in the PubMed and Cochrane databases to identify literature on CV complications resulting from the COVID-19 vaccine. All articles with relevant data and discussion regarding adverse effects of the COVID-19 vaccines were included in the review. In total, 4419 articles were screened, and 166 articles were included in the review. The vaccine-associated CV adverse events encompassed the following conditions: myocarditis, pericarditis, acute coronary syndrome, stress cardiomyopathy, hypertension, isolated tachycardia, myocardial infarction (MI) with nonobstructive coronary arteries (MINOCA), cardiac arrest, vaccine-induced thrombotic thrombocytopenia (VITT), MI, cerebral venous thrombosis (CVT), deep vein thrombosis (DVT), pulmonary embolism (PE), and other venous thrombotic disorders. Among these, myocarditis and thrombosis, especially VITT, emerged as the most frequently cited complications in the reviewed literature. Ranges of incidences for the following were recorded among the reviewed articles: myocarditis: 2 to 17 per million, VITT: 3-10 per million, CVST: 2.6-10 per million, MI: 3-4 per million. COVID-19 vaccines entail the potential for adverse events, although at low incidence, some of which exhibit notable severity. These adverse events exhibit demographic specificity and vaccine-specific profiles. The adverse events reviewed are uniformly acute in nature. The existing body of evidence offers limited support for the assertion that COVID-19 vaccines may elevate the baseline risk of CV events in the long term. However, the available research on effects greater than six months is scarce.

Events supposedly attributable to vaccination or immunization during pandemic influenza A (H1N1) vaccination campaigns in Latin America and the Caribbean

As part of the vaccination activities against influenza A[H1N1]pdm vaccine in 2009-2010, countries in Latin American and the Caribbean (LAC) implemented surveillance of events supposedly attributable to vaccines and immunization (ESAVI). We describe the serious ESAVI reported in LAC in order to further document the safety profile of this vaccine and highlight lessons learned. We reviewed data from serious H1N1 ESAVI cases from LAC countries reported to the Pan American Health Organization/World Health Organization. We estimated serious ESAVI rates by age and target group, as well as by clinical diagnosis, and completed descriptive analyses of final outcomes and classifications given in country. A total of 1000 serious ESAVI were reported by 18 of the 29 LAC countries that vaccinated against A[H1N1]pdm. The overall reporting rate in LAC was 6.91 serious ESAVI per million doses, with country reporting rates ranging from 0.77 to 64.68 per million doses. Rates were higher among pregnant women (16.25 per million doses) when compared to health care workers (13.54 per million doses) and individuals with chronic disease (4.03 per million doses). The top three most frequent diagnoses were febrile seizures (12.0%), Guillain-Barré Syndrome (10.5%) and acute pneumonia (8.0%). Almost half (49.1%) of the serious ESAVI were reported among children aged <18 years of age; within this group, the highest proportion of cases was reported among those aged <2 years (53.1%). Of all serious ESAVI reported, 37.8% were classified as coincidental, 35.3% as related to vaccine components, 26.4% as non-conclusive and 0.5% as a programmatic error. This regional overview of A[H1N1]pdm vaccine safety data in LAC estimated the rate of serious ESAVI at lower levels than other studies. However, the ESAVI diagnosis distribution is comparable to the published literature. Lessons learned can be applied in the response to future pandemics.

Regional advisory board position statement on optimal pneumococcal vaccination in adults. Update to 2011 consensus on adult pneumococcal disease: update on optimal pneumococcal vaccination in adults

BACKGROUND

An important development in the field of adult pneumococcal vaccination since the last Consensus Statement, published by the Expert Panel of Central and Eastern Europe and Israel (the Region) in September 2012, was the licensure of the 13-valent pneumococcal conjugate vaccine (PCV13) for adults aged 50 years and older.

DISCUSSION

The Expert Panel has developed this Position Statement as an update to its previous Consensus to address the following topics which are likely to be on the agenda of national scientific societies during the ongoing updates of vaccination recommendations in the Region: the availability of a pneumococcal conjugate vaccine for adults over 50 years of age, the available clinical evidence on its use in adults, and the future place of conjugate vaccines in adult pneumococcal vaccination. The Expert Panel concluded that there is sufficient epidemiologic immunogenicity and safety evidence to use PCV 13 in adults over 50 years of age.

RESULTS

The use of conjugate vaccine induces immunological memory and can overcome some limitations associated with the plain polysaccharide vaccine (PPV). It was also agreed that, if the use of PPV is considered appropriate, PCV13 should be administered first, regardless of prior pneumococcal vaccination status.

The reporting completeness of a passive safety surveillance system for pandemic (H1N1) 2009 vaccines: a capture-recapture analysis

Adverse events following pandemic (H1N1) 2009 vaccines ("2009 H1N1 vaccines") in Taiwan were passively reported to the National Adverse Drug Reaction Reporting System. To evaluate the completeness of spontaneous reporting, cases of death, Guillain-Barré syndrome (GBS), convulsion, Bell's palsy, and idiopathic thrombocytopenic purpura (ITP) after 2009 H1N1 vaccination that occurred between November 1, 2009 and August 31, 2010 were selected from the National Adverse Drug Reaction Reporting System (NADRRS) database and an additionally constructed nationwide large-linked database (LLDB), and matched on a unique personal identifier, date of vaccination (within ±7 days), and date of diagnosis (within ±7 days). Overall, matches occurred between the two data sources included 21 for death, 5 for GBS, 19 for convulsion, 22 for Bell's palsy, and 5 for ITP. The Chapman capture-recapture estimated spontaneous reporting completeness within 0-42 days of vaccination was 4% for death, 71% for GBS, 3% for convulsion, 9% for Bell's palsy, and 15% for ITP. For the interval ≥43 days after vaccination, reporting completeness was 0.1% for death, 14% for GBS, 0.1% for convulsion, <0.1% for Bell's palsy, and 0% for ITP. The estimated-to-expected ratio for Bell's palsy in the interval 0-42 days after vaccination was 1.48 (95% CI 1.11-1.98). Reporting completeness was higher for GBS than other adverse events after 2009 H1N1 vaccination. Linking the NADRRS to existing data sources in a capture-recapture analysis can be considered as an alternative to enhance Taiwan's postlicensure safety assessment of other routine vaccines. Nevertheless, the possibility of an increased risk for Bell's palsy detected by capture-recapture analyses needs further evaluation by controlled studies.

Adverse events following pandemic A (H1N1) 2009 monovalent vaccines in pregnant women--Taiwan, November 2009-August 2010

Background

During the 2009 H1N1 pandemic, pregnant women were prioritized to receive the unadjuvanted or MF59®-adjuvanted pandemic A (H1N1) 2009 monovalent vaccines (“2009 H1N1 vaccines”) in Taiwan regardless of stage of pregnancy. Monitoring adverse events following 2009 H1N1 vaccination in pregnant women was a priority for the mass immunization campaign beginning November 2009.

Methods/Findings

We characterized reports to the national passive surveillance from November 2009 through August 2010 involving adverse events following 2009 H1N1 vaccines among pregnant women. Reports from the passive surveillance were matched to a large-linked database on a unique identifier, date of vaccination, and date of diagnosis in a capture-recapture analysis to estimate the true number of spontaneous abortion after 2009 H1N1 vaccination. We verified 16 spontaneous abortions, 11 stillbirths, 4 neonatal deaths, 4 nonpregnancy-specific adverse events, and 2 inadvertent immunizations in recipients who were unaware of pregnancy at time of vaccination. The Chapman capture-recapture estimator of true number of spontaneous abortion after 2009 H1N1 vaccination was 329 (95% confidence interval [CI] 196–553). Of the 14,474 pregnant women who received the 2009 H1N1 vaccines, the estimated risk of spontaneous abortion was 2.3 (95% CI, 1.4–3.8) per 100 pregnancies, compared with a local background rate of 12.8 (95% CI, 12.8–12.9) per 100 pregnancies.

Conclusions

The passive surveillance provided rapid initial assessment of adverse events after 2009 H1N1 vaccination among pregnant women. Its findings were reassuring for the safety of 2009 H1N1 vaccines in pregnancy.

Safety of pandemic H1N1 vaccines in children and adolescents

During the 2009 influenza A (H1N1) pandemic several pandemic H1N1 vaccines were licensed using fast track procedures, with relatively limited data on the safety in children and adolescents. Different extensive safety monitoring efforts were put in place to ensure timely detection of adverse events following immunization. These combined efforts have generated large amounts of data on the safety of the different pandemic H1N1 vaccines, also in children and adolescents. In this overview we shortly summarize the safety experience with seasonal influenza vaccines as a background and focus on the clinical and post marketing safety data of the pandemic H1N1 vaccines in children. We identified 25 different clinical studies including 10,505 children and adolescents, both healthy and with underlying medical conditions, between the ages of 6 months and 23 years. In addition, large monitoring efforts have resulted in large amounts of data, with almost 13,000 individual case reports in children and adolescents to the WHO. However, the diversity in methods and data presentation in clinical study publications and publications of spontaneous reports hampered the analysis of safety of the different vaccines. As a result, relatively little has been learned on the comparative safety of these pandemic H1N1 vaccines - particularly in children. It should be a collective effort to give added value to the enormous work going into the individual studies by adhering to available guidelines for the collection, analysis, and presentation of vaccine safety data in clinical studies and to guidance for the clinical investigation of medicinal products in the pediatric population. Importantly the pandemic has brought us the beginning of an infrastructure for collaborative vaccine safety studies in the EU, USA and globally.