Top US Food and Drug Administration officials on Wednesday said the agency is aiming to decide by June whether to change the design of Covid-19 vaccines in order to combat future variants, even if it does not have all the necessary information to measure their effectiveness.

"We're going to have to think about this in a way that is less than optimal because we're not going to have all the data that we'd like to have," Peter Marks, director of FDA's Center for Biologics Evaluation and Research, said at a meeting of the agency's scientific advisers to discuss the issue.

Marks also conceded that...