The UK is the first country to approve vaccine boosters that target the omicron variant of COVID-19, paving the way for Brits to receive their shots in early fall.
The U.K. has approved the Moderna shot, which is a mix of two versions of the vaccine.
The head of the U.K.'s Medicines and Healthcare Products Regulatory Agency said in a statement that the vaccine gives them a "sharpened tool in their armoury" to protect against the disease.
The original 2020 strain of the coronaviruses and the original omicron variant were found to have a strong immune response against the Moderna-made omicron booster.
The booster that U.S. officials hope to release this fall has been approved in the U.K.
The FDA wants vaccine developers to focus on the two strains that make up the vast majority of cases here rather than the original omicron variant.
The Moderna shot was approved in the U.K. but it was less effective against the strain.
The side effects of the bivalent vaccine were similar to those of the original Moderna vaccine, and there were no serious safety concerns.
Moderna's bivalent booster is more effective against newer versions of the virus than the original vaccines are.
Bivalent shots are less effective against BA.4 and BA.5.
The wave of infections last year was caused by the original omicron variant. It has evolved into a number of different subvariants that have dominated the case. The BA.5 subvariant is the dominant one in the U.S.
Anthony Fauci is the top infectious disease official in the US.
The FDA asked vaccine manufacturers to create a bivalent vaccine that targeted BA.4 and BA.5 instead of the original omicron strain because of the likelihood of a winter surge.
Fauci said in an interview with NPR that he hoped that the variant would be close enough to evolve.
Sometime this fall, Americans will be able to purchase omicron-specific boosters.
More than 170 million omicron boosters have been purchased by the U.S. It's not enough for all Americans. Less than half of Americans have received a booster shot after completing their initial course.
The vaccine regulatory process is still going on. The boosters are expected to be authorized by mid- September.
CDC guidelines say that Americans who are 50 years old or older can get a second booster shot.
Some experts think that the new boosters for BA.4 and BA.5 will be worth waiting for.
Some people under the age of 50 have some protection. Even though the vaccine's effectiveness has waned, it still helps to prevent serious infections and hospitalization. Estimates show that as many as 80% of Americans have caught COVID-19.
It's possible that vaccines are less effective when taken too close together. If you're young and healthy, it's best to wait for the new booster this fall.
The concern is that if you get another vaccine so close to this one, you won't respond as well. In an interview with NPR, del Rio said that you have to have some time between vaccines. There's more risk than benefit if you get another booster now.
Rob Stein reports additional reporting.