Randomized clinical trials of COVID-19 vaccines: Do adenovirus-vector vaccines have beneficial non-specific effects?

• Published in: iScience
• Main Authors: Christine S. Benn, Frederik Schaltz-Buchholzer, Sebastian Nielsen, Mihai G. Netea, Peter Aaby
• Format: Article
• Language: English
• Published: Elsevier 2023-05-01
• Subjects: Microbiology; Virology
• Online Access: http://www.sciencedirect.com/science/article/pii/S2589004223008106
• ISSN: 2589-0042

Summary: We examined the possible non-specific effects of novel mRNA- and adenovirus-vector COVID-19 vaccines by reviewing the randomized control trials (RCTs) of mRNA and adenovirus-vector COVID-19 vaccines. We calculated mortality risk ratios (RRs) for mRNA COVID-19 vaccines vs. placebo recipients and compared them with the RR for adenovirus-vector COVID-19 vaccine recipients vs. controls. The RR for overall mortality of mRNA vaccines vs. placebo was 1.03 (95% confidence interval [CI]: 0.63–1.71). In the adenovirus-vector vaccine RCTs, the RR for overall mortality was 0.37 (0.19–0.70). The two vaccine types differed significantly with respect to impact on overall mortality (p = 0.015). The RCTs of COVID-19 vaccines were unblinded rapidly, and controls were vaccinated. The results may therefore not be representative of the long-term effects. However, the data argue for performing RCTs of mRNA and adenovirus-vector vaccines head-to-head comparing long-term effects on overall mortality.