Surveillance of adverse events following immunisation in Australia, COVID-19 vaccines, 2021.

Abstract: This report summarises Australia's spontaneous (passive) surveillance data for adverse events following immunisation (AEFI) for coronavirus disease 2019 (COVID-19) vaccines in 2021 reported to the Therapeutic Goods Administration (TGA). The TGA strongly promoted and facilitated adverse event reporting in preparation for, and during, the COVID-19 vaccine rollout as a core component of the most intensive vaccine safety monitoring ever conducted in Australia. There were 111,348 AEFI reports for COVID-19 vaccines administered in 2021, an annual AEFI reporting rate of 271.4 per 100,000 doses of COVID-19 vaccines administered to people aged ≥ 12 years. The annual AEFI reporting rate for non-COVID-19 vaccines in 2021 was 30.6 per 100,000 doses administered to people of all ages. Overall, the most frequently reported symptoms were headache, adverse events classified as 'gastrointestinal nonspecific symptoms and therapeutic procedures', myalgia, pyrexia and fatigue, which were consistent with common expected adverse events following COVID-19 vaccines used in Australia. The most commonly reported adverse events of special interest were myocarditis and/or pericarditis, followed by thrombosis and thromboembolism, and anaphylaxis. Of all COVID-19 vaccine AEFI reports, 762 (0.7%) included a fatal outcome, of which over 80% were in people aged ≥ 60 years. Thirteen deaths reported in 2021 were assessed as likely to be causally linked to vaccination. This report confirms the value of spontaneous post-marketing vaccine pharmacovigilance, especially in the context of new vaccines using novel vaccine technologies and near whole-of-population pandemic vaccination programs. The most frequently reported AEFI for COVID-19 vaccines were common, mild and temporary (lasting 1 or 2 days), and consistent with clinical trial and active surveillance data. Ongoing safety monitoring detected rare, unexpected conditions, such as myocarditis/pericarditis and thrombosis with thrombocytopenia syndrome (TTS), which were investigated and confirmed as safety signals, resulting in changes to vaccine recommendations and product information. The outcomes of TGA monitoring were published in weekly vaccine safety reports. Overall, COVID-19 vaccine safety monitoring provided critical information on the risks of vaccine related adverse events that enabled decisionmakers to undertake informed risk-benefit assessments.