FDA has released updated guidance detailing its plans to streamline authorization of COVID-19 vaccines adapted to more-infectious variants, such as the U.K. variant B.1.1.7, which is now present in dozens of states.

FDA’s guidance would require such companies to launch small clinical studies similar to those needed for annual flu vaccines.

It also encourages sponsors to test modified vaccines in unvaccinated as well as previously-vaccinated individuals.

“The FDA is committed to identifying efficient ways to modify medical products that either are in the pipeline or have been authorized for emergency use to address emerging variants,” said Acting FDA Commissioner Dr. Janet Woodcock in a statement.

Recent data suggest that variant B.1.429, initially found in California, is also more infectious than earlier lineages.

Complicating matters further, B.1.1.7 and B.1.429 have merged in a recombination process to create a new hybrid. Other known transmissible variants have emerged in South Africa and Brazil.

With SARS-CoV-2 variants of concern spreading in the U.S. and elsewhere, vaccine developers Pfizer (NYSE:PFE) and its partner BioNTech (NSDQ:BNTX), Moderna (NSDQ:MRNA) and others have committed to creating boosters against them.BioNTech CEO Uğur Şahin has said it would take about six weeks to adapt its vaccine to a new variant.