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The Centers for Disease Control and Prevention has authorized reformulated Covid vaccines that target the latest omicron subvariants for the fall, making it possible for many people to get an extra booster within days.
The agency’s independent vaccine committee voted 13 to 1 earlier Thursday in favor of the vaccines after reviewing available safety and effectiveness data during a nearly seven-hour meeting. CDC Director Dr. Rochelle Walensky signed off on the shots a few hours later, clearing the way for pharmacies to begin implementing the shots soon.
Pfizer’s omicron boosters were approved for people 12 years of age and older, while Moderna’s updated shots were approved for people 18 years of age and older. Eligible age groups can receive boosters at least two months after completing their main series or their most recent booster with the old vaccines.
Walensky said her decision followed a “comprehensive scientific assessment and robust scientific discussion.”
“If you’re eligible, there’s no bad time to get your Covid-19 booster, and I strongly encourage you to get it,” she said in a statement.
Pfizer plans to ask the Food and Drug Administration to also approve the new boosters for children ages 5 to 11 in early October, company executives told the committee Thursday.
The original vaccines will no longer be used as a booster in people aged 12 and over after the reformulated vaccines come online.
Public health officials are expecting a new wave of Covd infection this fall as immunity from old vaccines wanes, more contagious sub-variants of omicron spread and people spend more time indoors as the weather turns colder and families gather for the holidays.
The CDC and FDA hope the new boosters will provide more durable protection against infections, mild and severe illnesses. The reformulated injections target omicron BA.5, the dominant variant of Covid, as well as the strain that emerged in China more than two years ago.
So far, the US has provided 171 million doses of Pfizer and Moderna’s new boosters. More than 200 million people are eligible for the shots, according to the CDC. Dr. Sarah Oliver, a CDC official, told the committee Thursday that there should be enough vaccine to meet demand this fall.
There are no data on omicron BA.5 in humans
There’s no human trial data on the new BA.5 boosters, so it’s unclear how they’ll perform in the real world. The CDC and FDA used human data from clinical trials of injections targeting the original version of omicron, BA.1, which elicited a stronger immune response than the old vaccines.
Pfizer and Moderna were initially developing omicron boosters to target BA.1, but the FDA asked the companies to switch gears in June and instead develop BA.5 injections after the subvariant became dominant. The decision to focus on BA.5 did not leave enough time to wait for data from human trials before the fall vaccine launch.
The lack of human data on the BA.5 vaccines has caused some controversy, but Dr. Peter Marks, a senior FDA official, said the agency followed the same process used for years with strain changes for flu vaccines. Marks said Wednesday that flu vaccine strains are also changing without clinical data in humans.
Dr. Pablo Sanchez, the only panel member to vote against vaccines, called the recommendation premature and said the U.S. should have waited for human data before proceeding with boosters.
“There’s already a lot of hesitation about vaccines — we need the human data,” said Sanchez, professor of pediatrics at Ohio State University. But Sanchez said he believes the new boosters are safe and will likely get one himself.
Panel member Dr. Oliver Brooks, chief medical officer at Watts HealthCare Corporation in Los Angeles, asked why the FDA decided to use the BA.5 vaccine when there was clinical data on the BA.1 vaccines that the vaccine manufacturers were originally developing. In the end, Brooks voted in favor of the photos.
But Dr Sarah Long, also a member of the panel, said there was no reason to expect BA.5 boosters to be worse than the old vaccines as they also included the original strain of Covid and had the potential to reduce hospitalisations. and deaths heading into fall and winter. Long also voted yes.
FDA and CDC officials said the omicron BA.1 and omicron BA.5 boosters are similar enough that the immune response data from the BA.1 vaccine should give a good indication of how the BA.5 injections will perform. Omicron BA.1 and BA.5 are closely related with a difference of four mutations, according to Dr. Jacqueline Miller, who works on vaccine development at Moderna.
Moderna completed enrollment in clinical trials of the BA.5 injections last week and should have results by the end of the year, Miller told the CDC committee Thursday. Pfizer’s clinical trial is also ongoing, although the company has not said when it expects results.
The health agencies also reviewed data on BA.5 shots from mouse studies. Moderna presented data showing that BA.5 injections boosted antibodies in mice more than four times compared to the old injections. Mice express the same cellular protein as humans that the virus latches onto. Pfizer’s BA.5 booster boosted antibodies 2.6-fold in mice compared to the original vaccine.
The most common side effects from human trials of BA.1 injections are pain, redness, swelling at the injection site, fatigue, headache, muscle pain, joint pain, chills, nausea, vomiting and fever, according to the FDA.
Oliver, the CDC official, told the committee that health officials do not expect any difference in the safety profile of the BA.1 and BA.5 vaccines, given that the subvariants differ by only a few mutations.
But Oliver noted that the risk of myocarditis after a BA.5 booster is unknown. There is an increased risk of myocarditis among young men and adolescents after the second dose of the Pfizer and Moderna vaccines, but the risk of myocarditis from a Covid infection is higher, according to the CDC.
“We know the risk of myocarditis is unknown, but we expect a risk similar to that seen after monovalent vaccines,” Oliver said. Monovalent vaccines are the old vaccines that have been given to millions of people in the US for the past two years.
Old vaccines lose effectiveness
The original vaccines, which were first authorized in December 2020, no longer provide meaningful protection against infection because the virus has mutated so much over the past two years. The injections were developed against the first strain that appeared in China, so they are no longer suitable for targeting the omicron sub-variants that are spreading.
Infections, hospitalizations and deaths fell dramatically after last winter’s massive wave of omicron infection, but have remained stubbornly high this summer. Omicron BA.5 is the most infectious and immune-resistant variant to date, and breakthrough infections are becoming more common as a result.
The effectiveness of old vaccines against hospitalization also decreased after omicron BA.5 became dominant. A third dose was 77 percent effective in preventing hospitalization four months after receiving the shot, but protection declined after 120 days to 34 percent, according to CDC data. The fourth dose in people aged 50 and over was 56% effective in preventing hospitalization after four months.
Covid deaths and hospitalizations among people age 65 and older have increased since April, according to Heather Scobie, a CDC epidemiologist who presented data at Thursday’s meeting. Deaths have increased especially among people age 75 and older, Scobie said.
CDC has shifted to a more targeted public health response with an emphasis on protecting the most vulnerable — the elderly, people with serious medical conditions and those with weakened immune systems. Although there is no data on the actual effectiveness of the new boosters, the US is moving quickly to roll them out in hopes that they will protect people this fall.