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The Centers for Disease Control and Prevention’s Independent Vaccines Commission recommended reformulated booster shots targeting the latest omicron subvariants.
The panel voted 13 to 1 in favor of the shots on Thursday after reviewing available safety and effectiveness data in a nearly seven-hour meeting. CDC Director Dr. Rochelle Walensky has yet to issue the final sign before pharmacies can begin administering the boosters, but her approval is expected to follow soon.
Pfizer’s ommicron boosters are for people ages 12 and older, while Moderna’s updated shots are for adults ages 18 and older. The eligible age groups can receive the boosters at least two months after completing their primary series or their most recent booster with the old shots.
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 on Thursday.
The original vaccines will no longer be used as boosters in people 12 years and older as the reformulated injections come online.
Public health officials expect another wave of Covd infections this fall as immunity from the old vaccines wanes, more infectious omicron subvariants 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 infection, mild illness and severe illness. The reformulated shots target omicron BA.5, the dominant strain of Covid, as well as the strain that emerged in China more than two years ago.
The US has secured 171 million doses of the new boosters from Pfizer and Moderna to date. More than 200 million people are eligible for the injections, according to the CDC. dr. Sara Oliver, a CDC official, told the committee Thursday that there should be enough supply of the vaccine this fall to meet demand.
No ommicron BA.5 human data
There is no human trial data with the new BA.5 boosters, so it’s unclear how they will perform in the real world. The CDC and FDA used human data from clinical trials for shots that targeted the original version of omicron, BA.1, which elicited a stronger immune response than the old vaccines.
Pfizer and Moderna originally developed omicron boosters to target BA.1, but the FDA asked the companies to switch in June and instead develop BA.5 shots after the subvariant became dominant. The decision to focus on BA.5 did not leave enough time to wait for human trial data prior to the rollout of a fall vaccine.
The lack of human data for the BA.5 injections 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 on Wednesday that flu vaccine strains are also being changed without human clinical data.
dr. Pablo Sanchez, the only committee member to vote against the shots, called the recommendation premature and said the US should have waited for human data before proceeding with the boosters.
“There’s already a lot of hesitation about vaccines — we need the human data,” said Sanchez, a professor of pediatrics at Ohio State University. But Sanchez said he believes the new boosters are safe and that he will likely receive one himself.
Panel member Dr. Oliver Brooks, chief medical officer at Watts HealthCare Corporation in Los Angeles, wondered why the FDA decided to go with a BA.5 vaccine when clinical data is available for the BA.1 injections the vaccine makers are originally developing goods. Brooks eventually voted for the shots.
But dr. Sarah Long, also a committee member, said there is no reason to expect the BA.5 boosters to be inferior to the old shots as they also contain the original Covid strain and they have the potential to increase hospitalizations and deaths. way to fall and winter. Long also voted in favour.
FDA and CDC officials have said the omicron BA.1 and omicron BA.5 boosters are similar enough that the immune response data from the BA.1 injection should give a good indication of how the BA.5 injections will take. to 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 for clinical trials of the BA.5 injections last week and should have results by the end of the year, Miller told the CDC committee on Thursday. Pfizer’s clinical trial is also underway, although the company has not said when it expects results.
The health authorities also reviewed data on BA.5 recordings from mouse studies. Moderna presented data showing that the BA.5 shots more than quadrupled the antibodies in mice compared to the old shots. The mice express the same cell protein as humans to which the virus clings. Pfizer’s BA.5 booster increased antibodies in mice by a factor of 2.6 compared to the original vaccine.
The most common side effects from the trials of BA.1 in humans were pain, redness, swelling at the injection site, fatigue, headache, muscle aches, joint pain, chills, nausea, vomiting and fever, according to the FDA.
Oliver, the CDC official, told the committee that health officials do not expect a difference in the safety profile of the BA.1 and BA.5 shots, as subvariants differ only by a few mutations.
But Oliver noted that the risk of myocarditis after a BA.5 booster shot is unknown. There is an increased risk of myocarditis in young men and adolescent boys after the second dose of Pfizer and Moderna injections, but the risk of myocarditis from Covid infection is higher, the CDC said.
“We know the risk of myocarditis is unknown, but expect a similar risk as after the monovalent vaccines,” Oliver said. The monovalent vaccines are the old injections given to millions of people in the US over the past two years.
Old vaccines lose their effectiveness
The original vaccines, which were first approved in December 2020, no longer provide meaningful protection against infection because the virus has mutated so much over the past two years. The shots were developed against the first species that emerged in China, so they are no longer aligned with the ommicron sub-varieties that are spreading.
Infections, hospitalizations and deaths have fallen dramatically since last winter’s massive wave of omicron infections, but have reached a stubbornly high level this summer. Omicron BA.5 is the most contagious and immune-evasive variant to date, and as a result, breakthrough infections are becoming more common.
The effectiveness of old vaccines against hospitalization also declined after ommicron BA.5 became dominant. A third dose was 77% effective at preventing hospitalization four months after receiving the injection, but protection declined to just 34% after 120 days, according to CDC data. A fourth dose in people 50 years and older was 56% effective in preventing hospitalization after four months.
The number of deaths and hospitalizations from Covid among people 65 and older has increased since April, according to Heather Scobie, a CDC epidemiologist who presented data at Thursday’s meeting. Deaths have risen, especially among people 75 and older, Scobie said.
The CDC has moved to a more focused public health response with an emphasis on protecting the most vulnerable: the elderly, those with serious medical conditions, and those with weak immune systems. While there is no data on the actual effectiveness of the new boosters, the US is rapidly rolling them out in hopes of protecting people this fall.