Ryan Malosh, assistant research scientist at the University of Michigan School of Public Health, can comment on today's announcement by Pfizer and BioNTech. His research focuses on vaccine effectiveness, epidemiology and transmission of respiratory viruses, and social determinants of acute respiratory infection.
"The results of the interim efficacy analysis, shared today by Pfizer and BioNTech, on their COVID-19 vaccine candidate, are very promising," said Malosh, who is currently working on studies of COVID-19 in the community and household settings.
"The phase 3 clinical trial was large, with close to 39,000 participants receiving the recommended two doses of either the vaccine candidate or placebo. The reported efficacy is greater than 90%, which is very exciting. The press release noted that further data on efficacy and safety will be presented in the coming weeks.
"In this study cases were identified among participants with symptoms of a respiratory illness, so we cannot evaluate how well the vaccine works to prevent asymptomatic infections. These results are very encouraging, but as with any press release, we have to wait for more details to truly evaluate this study fully.
"We need more information, for example, on how long participants were followed in each group, and what symptoms those with confirmed infections were experiencing. We don't have any data here on how well the vaccine works to prevent severe disease or how well it works in specific age groups, both very important questions. The release further notes that 42% of global participants and 30% of U.S. participants have racially or ethnically diverse backgrounds, but given the disparities in incidence and severity of outcomes observed throughout the pandemic we need more data on the race and ethnicity of cases.
"Finally, it is important to remember that clinical trials represent how well the vaccine works under ideal conditions, and that additional studies will be needed to determine how well it works under real-world conditions."
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