FDA to announce tougher standards for a coronavirus vaccine that make it unlikely one will be cleared by Election Day

The guidance, which is far more rigorous than what was used for emergency clearance of hydroxychloroquine or convalescent plasma, is an effort to shore up confidence in an agency that has made missteps during the pandemic. With the vaccines, the FDA is expected to ask manufacturers seeking an emergency authorization — a far quicker process than a formal approval — to follow participants in late-stage clinical trials for a median of at least two months, starting after they receive a second vaccine shot, according to two individuals familiar with the situation who spoke on the condition of anonymity to discuss information before it is made public.

As a sign the vaccine works, the agency also is likely to look for at least five severe cases of covid-19, the disease caused by the coronavirus, in the placebo group for each trial, as well as some cases of the disease in older people.

These standards, plus the time it will take companies to prepare their applications and the agency to review the data, make it highly improbable any vaccine will be authorized before the election. The agency has previously said any vaccine would have to be 50 percent more effective than a placebo.  ...