FDA and CDC clear the way for updated COVID-19 vaccine boosters to target Omicron
Updated COVID-19 booster shots adapted for the Omicron variant are rolling out for Americans ages 12 and up after clearing the final regulatory hurdles on Thursday.
CDC Director Dr. Rochelle Walensky signed off on the recommendation following majority votes by a panel of the CDC's outside vaccine advisers backing the updated vaccines from Pfizer-BioNTech and Moderna. The Food and Drug Administration issued its authorization on Wednesday.
"This recommendation followed a comprehensive scientific evaluation and robust scientific discussion. If you are eligible, there is no bad time to get your COVID-19 booster and I strongly encourage you to receive it," Walensky said in a statement.
Shipments of doses have already begun, and many state and local health departments placed pre-orders last month for the first waves of deliveries.
"We have hundreds of thousands of doses being delivered around the country today, and by the end of the holiday weekend, millions of doses will be in the field, with more arriving every day," CDC's Sarah Meyer told a meeting of the agency's Advisory Committee on Immunization Practices.
Americans will be eligible to get the new booster as little as 2 months after their last shot of a COVID-19 vaccine.
Moderna's new booster shots are authorized for Americans as young as 18, while Pfizer and BioNTech's can be given down to age 12.
FDA officials told reporters on Wednesday that the age groups eligible for the new shots could be expanded even further over the next two months. Pfizer says it plans to submit a request to the FDA "in early October" for children down to 5 years old.
The new formulations mark the first substantial redesign to the design of the COVID-19 vaccines since they were rolled out earlier in the pandemic.
Vials of the so-called "bivalent" shots from each company blend together a component from their original "prototype" shots with new one designed to target the Omicron subvariants BA.4 and BA.5. The CDC estimates those strains now make up virtually every infection across the country.
Federal health officials have also touted the rollout as a key shift to simplify the nation's vaccination strategy, with Americans now able to get "up to date" on their COVID-19 protection with only a single shot of the updated vaccine.
"It's an important move towards simpler recommendations, as well as an updated vaccine that we expect to provide broader immune protection," the CDC's Dr. Melinda Wharton told the panel.
Some 209 million Americans will be eligible for the bivalent boosters, the CDC estimates. Boosters from the original formulation are no longer authorized for use in Americans who are eligible to get the new booster shots.
Why are the booster shots being changed?
The decision to tweak the design of the COVID-19 vaccines to target these strains stems from meetings of the FDA's outside vaccine advisers back in June and April earlier this year to weigh the issue, ahead of the months-long ramp-up required for manufacturers to redirect their vaccine factories.
A majority of the committee's members at the time favored an approach not far off from the one proposed by Pfizer and BioNTech to accelerate the authorization of new shots, in hopes of averting a repeat of the past two deadly winter waves of the virus.
The FDA ultimately said it would not require lengthy clinical trials of the shots aimed at BA.4 and BA.5 in humans before authorizing the new booster supply from Moderna as well as Pfizer and BioNTech.
Instead, the authorization would rely largely on trial data collected from testing the safety and immune response triggered by the new shots in animals, as well as data from other formulations previously trialed by the vaccine makers.
"In the midst of a pandemic, if you wait for all that data to come in, you've missed the boat. And so you have to be preemptive," FDA Commissioner Dr. Robert Califf said on the "Public Health On Call" podcast on Tuesday.
Califf compared the authorization to the regulator's approach to updating the annual flu vaccine, citing "the totality of the evidence" backing their decision.
Even with the authorization in hand, the two vaccine makers say they are still planning to complete human clinical trials of these new shots.
FDA officials say key data from those studies measuring the immune response of the vaccines against virus variants are expected in the next two months.
Data presented to the CDC's advisers on Thursday estimated that the effectiveness of the original vaccines against symptomatic Omicron infections during recent waves had waned to nearly zero within months after vaccination. However, officials said effectiveness "continues to be higher and more sustained over time" against COVID-19 hospitalization, especially in boosted Americans.
Rolling out bivalent booster shots
Twenty million doses were made available for jurisdictions and other vaccinators to pre-order, the Administration for Strategic Preparedness and Response said Thursday. All 50 states and the District of Columbia have requested shots, which federal officials expect to begin "in earnest" following the Labor Day weekend.
Spokespeople for national pharmacy chains, including Walgreens, CVS, Walmart, and Rite Aid, say they plan to begin accepting appointments for the new shots over the coming days as supply arrives in their stores.
Planning documents published by the CDC last month urged state and local health departments to prepare to distribute the early shipments to providers that can vaccinate "those at highest risk for severe COVID-19 disease" first, like in nursing homes.
In a first for the COVID-19 vaccines, part of the supply of new shots the Biden administration purchased from Pfizer and BioNTech are expected to come in single-dose vials. Approved by the FDA last month, these vials could dramatically cut down on wasted doses and make it easier for providers to offer the shots.
However, the initial tranche of bivalent shots from Pfizer are expected to be far more unwieldy: cartons of 10 vials containing 6 doses each, shipped in minimum orders of 300 doses. Moderna's vaccine will come in minimum orders of 100 doses.
The new booster campaign could also make it harder for unvaccinated Americans to find primary series shots, which will still require the original formula. The U.S. is currently averaging less than 40,000 first doses a day, according to CDC figures.
Human clinical trial results will be needed before the primary series of shots can be switched, the FDA said earlier this year.
"It is expected that many COVID-19 vaccination providers will offer bivalent booster doses, but not all providers are expected to continue carrying primary series COVID-19 vaccines," the CDC said in its planning guide.
The push for new fall booster shots will not be without its hurdles for health departments, which are now also juggling annual flu shots with multiple public health emergencies.
"Your state and local health department colleagues are now in their third year, as well as our health clinicians, of COVID pandemic response, as well as trying to respond to monkeypox outbreak and vaccination campaigns, on top of other local infectious disease outbreaks," ACIP member Dr. Jeffrey Duchin said. Duchin is the top public health official in Washington state's Seattle and King County.
"We have not received additional COVID funding. We have not received any monkeypox funding. And we are very much running on fumes," Duchin told the committee.