Pfizer says COVID recall offers protection against omicron variant

Pfizer said Wednesday that a booster of its COVID-19 vaccine could offer significant protection against the new omicron variant even though the initial two doses appear significantly less effective.

Pfizer and partner BioNTech said that while two doses may not be strong enough to prevent infection, lab tests showed a 25-fold boost in antibody levels able to fight the omicron. For people who have not yet received a booster, the companies said two doses should still prevent serious illness or death.

Health authorities in the United States and other countries have urged eligible people to receive a third dose even before these results.

“Get your third boost ASAP,” Pfizer Chief Scientific Officer Dr. Mikael Dolsten told The Associated Press. “It’s heartwarming and a very positive message that we now have a plan that will induce immunity that can protect against infections, symptomatic illnesses and serious illnesses from now on throughout the winter season.”

President Joe Biden said the discovery of the Pfizer recall is “very encouraging” although he cautioned, “that’s the report from the lab. There are more studies going on.

Pfizer and BioNTech tested blood samples taken one month after a booster and found that people had levels of omicron-neutralizing antibodies similar to the amounts shown to be protective against earlier variants after two doses. For the lab tests, the researchers cultured samples of so-called “pseudoviruses” that contain the worrying new mutations.

Scientists don’t yet know how much of a real threat the omicron variant poses. Currently, the extra-contagious delta variant is responsible for most cases of COVID-19 in the United States and other countries.

But the omicron variant, discovered late last month, carries an unusually high number of mutations and scientists are racing to find out how easily it spreads, whether it causes more severe or milder disease than other types. of coronavirus – and to what extent it could escape the protection of previous vaccinations.

Pfizer’s findings, announced in a press release, are preliminary and have not yet undergone scientific review. But they are the first from a vaccine maker to examine whether the booster doses that health authorities are urging people to get can actually make a key difference.

Moderna and Johnson & Johnson are also testing their vaccines for resistance, but health authorities will be watching closely for concrete evidence of the spread of omicron in highly vaccinated populations.

If it becomes dominant and causes serious illness, regulators will have to decide whether vaccines need to be changed to better match omicron — recipe changes that manufacturers are already beginning, just in case.

Scientists have speculated that the high jump in antibodies that accompanies a third dose of current COVID-19 vaccines might be enough to counter any decrease in effectiveness.

Despite the large number of mutations omicron carries, “it’s still not a full escape variant, it’s a partial escape variant,” BioNTech CEO Ugur Sahin said during a briefing. press conference.

Antibody levels predict how well a vaccine can prevent coronavirus infection, but they are only one layer of the immune system’s defences. Pfizer said two doses of the vaccine should still protect against severe disease, because omicron mutations don’t appear to impede another defense – T cells that fight the virus after infection.

A small laboratory study in South Africa also concluded that people may be more susceptible to breakthrough infections with omicron after just two doses of Pfizer. Scientists at the Africa Health Research Institute in Durban found a sharp drop in antibody strength against omicron compared to other variants, although they did not test the boosters. Pfizer boosters are not yet available in South Africa, but health workers are being offered extra doses of the single-shot J&J vaccine.

Preliminary results from South Africa suggest that people vaccinated after a previous episode of COVID-19 retained more protection – reflecting that initial injections are known to trigger a huge jump in antibodies after a previous infection.

Even if there are more breakthrough infections after two doses, most experts believe vaccines will still work against the omicron variant because of the other immune defenses they trigger, said Willem Hanekom, co-author of the South African study.

“The more antibodies you can have on board, the better you’ll do, at least in these lab experiments,” Hanekom said. “So booster shots could be very important.”

A US expert agreed that preliminary results from the recall are encouraging, although more information is needed.

But if omicron ends up causing serious disease and becoming common around the world, “it could be much better treated with vaccines that are tailored to specifically protect against this variant,” said Dr Jesse Goodman of the University of Georgetown, former head of vaccines for the Food and Drug Administration. .

Vaccine manufacturers are already tweaking their vaccine recipes to create an omicron-specific dose when needed. Pfizer predicted its nominee could be ready for review by regulators in March.

About Sandra A. Powell

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