COVID-19 vaccine manufacturers should include the newer forms of the omicron coronavirus variant in booster shots this fall, the Food and Drug Administration recommended today.

The agency said it wants vaccine manufacturers to create booster shots that include two forms of the virus — the original strain, which is what’s in current vaccines, and the BA.4 and BA.5 lineages of the omicron variant. Those lineages have taken over as the most common form of the virus circulating in the United States. They’re highly contagious and are even better at evading the immune system than some previous versions of the virus.

Vaccine manufacturers Pfizer, Moderna, and Novavax have already been testing omicron-targeted versions of their vaccines, which early data showing that they can help trigger a stronger immune response to the omicron variant than existing shots. The versions they’ve been testing, though, include an earlier form of the omicron variant — the BA.1 lineage. Companies should do additional clinical trials on BA.4 and BA.5 shots, the FDA said in a statement, but should still send in data from the BA.1 shots.

The current iterations of the COVID-19 vaccines still protect extremely well against severe disease and death, but a combination of waning immunity and new variants has left people less protected against infection. Experts hope that the next generation of shots will offer longer-lasting protection against the disease.