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The Centers for Disease Control and Prevention have released reformulated Covid shots targeting the latest Omicron subvariants for the fall, allowing many people to get an extra boost in days.
The agency’s independent committee on vaccines voted 13-1 in favor of the shots on Thursday after reviewing the available safety and efficacy data in a nearly seven-hour session. CDC Director Dr. Rochelle Walensky approved the injections a few hours later, clearing the way for pharmacies to administer the injections soon.
Pfizer’s Omicron boosters were approved for ages 12+, while Moderna’s updated shots were approved for ages 18+. The eligible age groups can receive the boosters no earlier than two months after the completion of their primary series or their last booster with the old vaccinations.
Walensky said her decision followed “a thorough scientific evaluation and sound scientific discussion.”
“If you are eligible, there is 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 are no longer used as a booster dose in people aged 12 and over as the reformulated vaccines are now online.
Public health officials expect another wave of Covid infections this fall as immunity to the legacy vaccines wanes, more contagious omicron subvariants spread and people spend more time indoors as the weather turns colder and families close gather for the holidays.
The CDC and FDA hope the new boosters will provide more durable protection against infection, mild illness, and serious illness. The reformulated shots target omicron BA.5, the dominant variant of Covid, as well as the strain that emerged in China more than two years ago.
The US has so far secured 171 million doses of the new boosters from Pfizer and Moderna. More than 200 million people are entitled to the recordings, according to the CDC. dr Sara Oliver, a CDC official, told the committee Thursday there should be enough vaccine supplies to meet demand this fall.
No omicron BA.5 human data
There is no human trial data on the new BA.5 boosters, so it is unclear how they will perform in the real world. The CDC and FDA used human clinical trial data for vaccinations against the original version of Omicron, BA.1, which elicited a stronger immune response than the old vaccines.
Pfizer and Moderna originally developed Omicron boosters for BA.1, but the FDA told the companies to change gears in June and develop BA.5 shots instead 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 a vaccine launch in the fall.
The lack of human data for the BA.5 vaccines has caused some controversy, but Dr. Peter Marks, a senior FDA official, said the agency has followed the same process it has used for years to change strains for flu vaccines. Marks said Wednesday flu vaccine strains are being changed even without human clinical data.
dr Pablo Sanchez, the only committee member who voted against the injections, 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 with 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 he will likely receive one himself.
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Board member Dr. Oliver Brooks, chief medical officer at Watts HealthCare Corporation in Los Angeles, questioned why the FDA chose a BA.5 vaccine when clinical data is available for the BA.1 vaccine that vaccine manufacturers are initially developing had. Brooks eventually voted for the shots.
But dr Sarah Long, also a committee member, said there was no reason to believe the BA.5 boosters will be inferior to the old vaccines as they also contain the original Covid strain and have the potential to increase hospitalizations and deaths along the way in the future to reduce autumn and winter. Long also voted in favour.
FDA and CDC officials have said that the omicron BA.1 and omicron BA.5 boosters are similar enough that the immune response data of the BA.1 vaccine should give a good indication of how the BA.5 vaccine will work. Omicron BA.1 and BA.5 are according to Dr. Jacqueline Miller, who works on vaccine development at Moderna, are closely related and share a difference of four mutations.
Moderna completed enrollment in clinical trials on the BA.5 shots 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 ongoing, although the company hasn’t said when it expects results.
Health authorities also reviewed data on the BA.5 shots from mouse studies. Moderna presented data showing that the BA.5 shots increased antibodies in mice more than four-fold compared to the old shots. The mice express the same cellular protein as humans, to which the virus attaches. Pfizer’s BA.5 booster increased antibodies in mice by 2.6-fold compared to the original vaccine.
According to the FDA, the most common side effects from the human trials of BA.1 syringes were pain, redness, swelling at the injection site, fatigue, headache, muscle pain, joint pain, chills, nausea, vomiting, and fever.
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 because the subvariants differ by only a few mutations.
However, Oliver noted that the risk of myocarditis following a BA.5 booster dose is unknown. Young men and adolescent boys are at increased risk of myocarditis after the second dose of Pfizer and Moderna, but the risk of myocarditis from Covid infection is higher, according to the CDC.
“We know that the risk of myocarditis is unknown, but expect a risk similar to that seen after the monovalent vaccines,” Oliver said. The monovalent vaccines are the old vaccines that have been given to millions of people in the US over the last two years.
Old vaccines are losing their effectiveness
The original vaccines, which were first approved in December 2020, no longer offer any meaningful protection against infection because the virus has mutated so much in the last two years. The shots were developed against the first strain to appear in China, so they are no longer tailored to attack the expanding Omicron subvariants.
Infections, hospitalizations and deaths have all fallen dramatically since last winter’s massive Omicron outbreak, but have leveled off at stubbornly high levels this summer. Omicron BA.5 is the most contagious and immune-avoidable variant to date, and breakthrough infections have become increasingly common as a result.
The effectiveness of the old vaccines against hospitalization also decreased after omicron BA.5 became dominant. A third dose was 77% effective at preventive hospitalization four months after receiving the shot, but protection dropped to as much as 34% at 120 days, according to CDC data. A fourth dose in people aged 50 and over was 56% effective in preventing hospitalization at four months.
Deaths and hospitalizations from Covid among people aged 65 and older have increased since April, according to Heather Scobie, a CDC epidemiologist who presented data during Thursday’s meeting. The number of deaths has increased, particularly among people aged 75 and over, Scobie said.
The CDC has shifted to a more focused public health response, with a focus on protecting the most vulnerable — the elderly, those with serious illnesses and those with weakened immune systems. Though there’s no data on the real-world effectiveness of the new boosters, the US is moving quickly to introduce them in hopes they’ll protect people this fall.