Real-world Nuvaxovid COVID-19 vaccine safety profile after first 100,000 doses in Australia, 2022-2023

IntroductionNuvaxovid became available in Australia from February 2022, a year later than the first COVID-19 vaccines were released. It was a much-anticipated alternative vaccine for people that had either suffered an adverse event to-and/or were hesitant to receive-one of the mRNA or adenovirus-based COVID-19 vaccines. Although safety from clinical trials was reassuring, small trial population size, relatively low administration rates worldwide and limited post-licensure intelligence meant potential rare adverse events were underinformed. MethodsWe conducted a retrospective observational analysis of adverse events following immunisation (AEFI) spontaneously reported to SAFEVAC, the integrated vaccine safety surveillance system used by Victoria and Western Australia, Australia. Reports received from 14 Feb 2022 to 30 June 2023 were analysed by vaccinee demographics, reported reactions and COVID-19 vaccine dose received and compared as reporting rates (RR) per 100,000 doses administered. Results356 AEFI reports were received, following 102,946 Nuvaxovid doses administered. Rates were higher post dose 1 than dose 2 (rate ratio 1.5, p=0.0008); primary series than booster (rate ratio 2.4, p<0.0001); in females than males (rate ratio 1.4, p<0.01), especially those aged 30-49 years (RR=1.6, p=0.002). Serious AEFI included 76 chest pain (RR=73.8), two myocarditis (RR=1.9) and 20 pericarditis (RR=19.4). No cases of Guillain-Barre or thrombosis with thrombocytopaenia syndromes were reported and no deaths attributable to vaccination. ConclusionThe shared SAFEVAC platform enables pooling of clinically reviewed data across jurisdictions, increasing the safety profile evidence-base of novel vaccines like Nuvaxovid and improving the odds for identification and description of rare events across all vaccines. O_TEXTBOXKey public health messageO_ST_ABSWhat did you want to address in this study and why?C_ST_ABSNuvaxovid is a protein-based vaccine for protection against COVID-19. Nuvaxovid received provisional licensure following clinical trials in which 30,058 participants received at least one dose of Nuvaxovid. Introduced following adenoviral vector and mRNA COVID-19 vaccines, some people had been waiting for this vaccine as an alternative to other brands that had risk of blood clots or heart inflammation. We wanted to inform on safety of Nuvaxovid following over 100,000 doses administered in real-world population-wide setting in two Australian states. What have we learnt from this study?Adverse events reported were mostly mild, transient symptoms and no deaths were attributed to Nuvaxovid immunisation. Reporting rate for heart inflammation was similar to the mRNA COVID-19 vaccines, but more likely to be milder pericarditis than myocarditis. For over 25,000 people Nuvaxovid was their first dose of a COVID-19 vaccine received, despite being more than a year since COVID-19 vaccines became available. What are the implications of your findings for public health?This first real-world population-wide evidence of Nuvaxovid vaccine safety provides reassurance on the risk-benefit of vaccination for protection from severe COVID-19 disease. We must continue to look hard, using real-world data, to not only ensure vaccines are safe, but also support confidence in immunisation. C_TEXTBOX