With Omicron evolving into more contagious subvariants and another COVID-19 outbreak on the horizon, scientists are racing against time to update vaccines to better protect against the virus.

A Federal Drug Administration panel this week recommended that new shots be developed that target Omicron by this fall, when experts predict a new wave of COVID will hit.

Ulysses Wu, MD, chief epidemiologist for Hartford HealthCare, said the sooner new vaccines are developed the better, as he expects another outbreak this fall fueled by waning vaccine efficacy, people spending more time indoors and new Omicron subvariants emerging.

Current vaccines were all developed to protect against the original COVID strain that first emerged in Wuhan, China, in 2019. But as the virus has evolved through the pandemic, vaccines have become less effective.

Connecticut’s COVID-19 positivity rate is around 8.1 percent, and experts are concerned about two new variants spreading in the state.

Here’s what you need to know about BA.4 and BA.5, two offshoots of the pesky Omicron variant that has kept the virus more prevalent than expected this spring and summer. The new strains are:

“People who are counting on, ‘I’m free for a couple months now because I got COVID,’ not true,” said Dr. Wu.

As of June 3, BA.4 and BA.5 made up about 20 percent of Connecticut’s COVID-19 cases, and are likely to become the dominant strains as summer progresses. The Centers for Disease Control and Prevention says the variants make up at least a quarter of cases nationwide.

Wu said BA.4 and BA.5 could keep positivity rates relatively high in Connecticut during the summer months – at a time when some expected a drop off in cases.

“They will blunt our descent,” Wu said. “That’s probably why we have this saw-tooth pattern — up one day, down one day. I do believe [the variants are] contributing to that to a certain extent.”