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The UK has become the first country to approve vaccine boosters designed to target the omicron variant of COVID-19, paving the way for Britons to receive their shots in early autumn.
The Moderna vaccine approved in the UK is “bivalent”, meaning it is a mixture of two versions of the vaccine: half is for the original strain of COVID-19, and the other half is a new formulation designed to combat the original omicron variant, also known as BA.1.
“What this bivalent vaccine gives us is a sharp tool in our arsenal to help protect us against this disease as the virus continues to evolve,” said Dr June Raine, head of the UK Food Regulatory Agency. medicines and health products, said in a press release.
UK researchers have found that the omicron booster made by Moderna “triggers a strong immune response” against the original 2020 strain of coronavirus and the original omicron variant, which emerged late last year.
What has been approved in the UK is a different vaccine than the specific omicron booster that US officials hope to release this fall.
Here in the United States, the FDA has asked vaccine developers to target omicron subvariants known as BA.4 and BA.5 – the two strains that currently make up the vast majority of cases here – rather than focusing on the original omicron variant, which swept the country last winter.
Moderna’s shot approved on Monday in the UK was less effective against BA.5 – although it “still generates[d] a good immune response” against this strain, the researchers said.
UK regulators also found that the side effects of the bivalent vaccine were similar to those of the original Moderna vaccine – “generally mild and self-resolving” – and that there were no serious safety concerns.
Why does the United States want different omicron boosters?
Modern‘s bivalent booster – with a similar one made by Pfizer and BioNTech – is more effective against new variants of the virus than are the original vaccines.
But these bivalent shots were designed around the original omicron variant and as a result they are less effective against BA.4 and BA.5.
The original omicron variant emerged in late 2021 and contributed to the massive wave of infections during the holiday season last year. It has since mutated into a handful of different sub-variants which, one by one, have come to dominate the workload. Now the BA.5 subvariant is dominant in the United States, accounting for nearly 90% of all cases.
This rapid change in the composition of the virus has been “a moving target” for health officials trying to guide vaccine policy, said Dr. Anthony Fauci, the United States’ top infectious disease official. United.
In late June, the FDA, aware of the likelihood of another winter flare, decided to ask vaccine makers to create a bivalent vaccine targeting BA.4 and BA.5, rather than the original omicron strain.
“Hopefully it will be close enough to the variant that will evolve as we move into fall and winter,” Fauci said. in an interview with NPR late last month.
When will omicron boosters be available in the United States?
Officials have reported that omicron-specific boosters will be available to Americans this fall.
The United States bought more than 170 million total doses omicron boosters from Pfizer and Moderna. (That’s not enough for the 330 million Americans. But only about two-thirds of Americans have completed their initial course of the vaccine, and less than half of them have received boosters.)
The regulatory process that helps show that vaccines are safe and effective is still ongoing. Officials said they hope to clear the boosters by mid-September.
Can I just get another original booster now?
Americans 50 or older, as well as some immunocompromised people, can already get a second booster shot, according to CDC guidelines.
For others, some experts say the new BA.4 and BA.5 specific boosters are due soon enough to make the wait worthwhile.
Most people under 50 who have no underlying conditions already have some protection. Even though the effectiveness of the original vaccine and the booster has diminished, they still help, especially in preventing serious infections and hospitalizations. In addition, some estimates say up to 80% of Americans have caught COVID-19adding natural immunity to the mix.
Also, vaccines may be less effective when taken too close together. Overall, if you’re young and healthy, it might be best to wait for the new booster this fall, said Dr. Carlos del Rio, an infectious disease specialist at Emory University.
“If you’re getting a vaccine right now, the problem is you won’t respond as well when you get another vaccine so close to this one. You need to have some time between vaccine doses,” del Rio said. . in an interview with NPR earlier this month. “In other words, there are more risks than benefits in getting another recall right now.”
Additional reporting by NPR’s Rob Stein.