The FDA wants to be sure Omicron shots and therapies work safely and can be made correctly before authorizing their use, while moving as quickly as it can to conduct the assessment to aid efforts to stay ahead of the variant, according to people familiar with the matter.

Under the rules that the FDA is putting into place, drugmakers working on new vaccines would be expected to meet standards similar to those required for authorization of boosters, a person familiar with the matter said.

For vaccines, the companies wouldn’t have to conduct large, lengthy trials enrolling thousands of subjects that wait for a certain number to catch symptomatic Covid-19. Instead, they could, for example, study the immune responses in a few hundred subjects.

Drugmakers would need about three months to develop and test the new vaccines, a person familiar with the matter said. Then the companies would seek authorization of the shots through an expedited review process, and it would take the FDA one to two weeks to make a decision, according to the person.