(AP) – Pfizer said on Wednesday that a booster dose of its COVID-19 vaccine could offer significant protection against the new omicron variant even though the initial two doses appear to be significantly less effective.
Pfizer and its partner BioNTech said that while two doses may not be protective enough to prevent infection, lab tests have shown that a booster increases anti-virus antibody levels in people by 25 times.
Blood samples taken a month after a booster showed people had levels of omicron neutralizing antibodies that were similar to the amounts proven to protect against previous variants after two doses.
Scientists do not yet know how much of a threat the omicron variant is. 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 rushing 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 been scientifically reviewed. But they’re the first from a vaccine maker to examine whether the booster doses health officials are urging people to get can actually make a significant difference.
Scientists have speculated that the high jump in antibodies that accompanies a third dose of COVID-19 vaccines may be enough to counter any decrease in effectiveness.
Pfizer and BioNTech are already working on creating an omicron-specific vaccine in case it is needed.
Antibody levels predict how well a vaccine can prevent coronavirus infection, but they’re just one layer of the immune system’s defenses. Pfizer said two doses of the vaccine should always protect against serious illness, because mutations in omicron don’t appear to hamper any of those other defenses, the T cells that fight the virus after infection.
“Although two doses of the vaccine may still offer protection against serious illness caused by the Omicron strain, it is clear from this preliminary data that protection is maximized with a third dose of our vaccine,” said Albert Bourla, CEO of Pfizer, in a statement.
Pfizer’s announcement had an immediate impact on US markets. Futures that had indicated a lower open reverse within seconds and swung solidly to the positive with the Dow Jones jumping nearly 200 points.
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