Engagement in Meaningful Activities Among Older Adults With Disability, Dementia, and Depression

trials.Among the 21 vaccines, 17 (81.0%)had at least 1 pivotal efficacy trial that used masking, 20 (95.2%) that used an active or placebo comparator group, and 8 (38.1%) approved based on a clinical primary end point; of these, the median vaccine efficacy was 91.9% (IQR, 79.6%-98.0%)(Table 2).Among the 5 vaccines for diseases for which no FDA-approved vaccine existed at time of approval, 4 (80%) used a clinical primary end point.Discussion | Since 2010, most novel vaccines approved by the FDA required about 8 years of clinical development and were based on evidence from a median of 7 clinical trials, including at least 2 pivotal efficacy trials that were randomized, masked, and used a comparator group.These pivotal efficacy trials enrolled a median of 5000 patients, who were followed up for serious adverse events for at least 6 months.Given the urgency of developing a COVID-19 vaccine, trials will need to be larger than those supporting prior vaccine approvals and include sufficient follow-up time for emergence of adverse effects.