According to Thursday’s announcement by the Food and Drug Administration, the next round of Covid booster shot should be modified in order to target the highly contagious subvariants BA.4 and BA.5, which are extremely contagious.

Pfizer BioNTech and Moderna were asked by the FDA to create so-called bivalent vaccines. These vaccines are intended to target both the original coronavirus strain and the BA.4/BA.5 subvariants. Dr. Peter Marks is the FDA’s top vaccine regulator.

Marks stated, “As we enter the fall and winter, we need safe and effective vaccine boosters that provide protection against circulating or emerging variants to avoid the most severe consequences from Covid-19.”

According to Marks, the FDA expects that the updated vaccines are available in October for a booster campaign.

According to the Centers for Disease Control and Prevention, the BA.4 and BA.5 Subvariants were the most contagious variants of the virus and accounted for 52% of all new Covid cases in America for the week ended June 25. In the same week, BA.1, an original variant of the omicron virus, accounted for 0% of all new cases.

Moderna and Pfizer have created shots that target both the original coronavirus and the BA.1. These vaccines increased the immune response to this strain but provided less protection against BA.4 or BA.5.

Pfizer stated to NBC News that an updated vaccine targeting BA.4 or BA.5 could be ready for distribution by the first week in October.

Moderna did not respond immediately to a request to comment. However, the company previously stated that it was ready to update its vaccine if necessary.

Complete coverage of the Covid-19 pandemic

Omicron and its expanding family of subvariants have hampered the effectiveness of Pfizer and Moderna’s current vaccines. These vaccines are still in their initial iteration and were designed to target the coronavirus strain that was discovered in Wuhan, China in late 2019.

The federal government hopes that the vaccinations can be updated to better match the circulating strains, which will increase their effectiveness and provide long-lasting immunity. This approach is similar to that used to administer the flu shot. Each year, scientists update the vaccines to target the most prevalent strains.

The FDA’s vaccine advisory panel overwhelmingly voted Tuesday in favor of recommending booster shots contain a component that targets omicron variant.

However, the panel did not specify which strain of omicron boosters should target. That was up to the FDA scientists. However, many members of the committee preferred a vaccine targeting BA.4 or BA.5.

According to FDA guidance, the companies will need to submit data showing that the bivalent vaccines BA.4/BA.5 trigger an immune response similar to existing vaccines.