All covid-19 vaccines currently in use in the US are available under emergency access only. None of the covid-19 vaccines in use are actually "approved." Through an emergency access mechanism known as Emergency Use Authorisation (EUA), the products being rolled out still technically remain "investigational." Factsheets distributed to vaccinees are clear: "There is no FDA approved vaccine to prevent covid-19." One key difference between EUA and approval (also called "licensure," and which for vaccines is known as a BLA (Biologics License Application)) was the expected length of follow-up of trial participants. Unlike its clear articulation of two months for an EUA, the FDA has not committed to a clear minimum for approval. Among the six "first in disease" vaccines approved by the FDA since 2006, pre-licensure pivotal trials were a median of 23 months in duration. Duration of protection is not the only question that longer, placebo controlled trials can address. They also address vaccine safety. The BMJ asked Moderna, Pfizer, and Janssen (Johnson and Johnson) what proportion of trial participants were now formally unblinded, and how many originally allocated to placebo have now received a vaccine. Pfizer declined to say, but Moderna announced that "as of April 13, all placebo participants have been offered the Moderna covid-19 vaccine and 98% of those have received the vaccine." In other words, the trial is unblinded, and the placebo group no longer exists.