Do COVID-19 Vaccines Protect Against Omicron? Pfizer and Moderna Boosters Show Promise
The Omicron variant of COVID-19, listed as a variant of concern by the World Health Organization, is spreading rapidly throughout the United States.
Both Pfizer and Moderna say preliminary studies show antibody protection is improved with a third dose of their vaccines.
For now, much remains unknown about the variant, and the CDC and FDA are exploring potential Omicron-specific boosters with Moderna, Pfizer, and Johnson & Johnson.
The first detected case of the Omicron variant in the United States was announced on December 1—and with case counts doubling as quickly as every day and a half, the Centers for Disease Control and Prevention (CDC) expects it to become the dominant strain in a matter of weeks. Now, there’s one question researchers are racing to answer: Do the COVID-19 vaccines and boosters protect against Omicron?
Here’s what we know so far: The Omicron variant, a new strain of SARS-CoV-2, the virus that causes COVID-19, was designated a variant of concern by the World Health Organization (WHO) on November 26. It’s been detected throughout the United States, and although it was only responsible for about 3% of domestic COVID-19 cases as of December 11, experts say it’s poised to unseat Delta as the dominant variant very soon.
This variant features a high number of mutations, meaning it’s unique from other strains like Delta—and these mutations could allow it to slip past the immune systems of both the vaccinated and those who have already had COVID-19, the World Health Organization (WHO) says; it appears to be harder for existing antibodies to recognize. It also seems to spread between people much more easily than other variants, the WHO reports.
A study from South Africa, where Omicron was first detected, found that two doses of Pfizer provided 70% protection against severe COVID-19 and 33% protection against infection during the wave of Omicron infections in the country; people who previously had COVID-19 had a “significantly higher” likelihood of breakthrough infections.
Amid these revelations, both experts and the public are now questioning how effective vaccines could be against the variant. But researchers are still waiting for more data on how effective the vaccines and boosters are against Omicron, plus whether it’s more contagious or dangerous than other strains. The CDC recommends that everyone age 5 and above get their first rounds of vaccines, while adults 18 and older roll up their sleeves again for a booster dose.
How effective are the available vaccines at protecting against Omicron? Are boosters necessary for full protection? And will Omicron-specific vaccines become necessary? This is everything we know about Omicron and the vaccines, according to doctors.
How effective are the COVID-19 vaccines against Omicron?
“There’s every reason to believe that if you get vaccinated and boosted, you would have at least some degree of cross-protection, very likely against severe disease, even against the Omicron variant,” Anthony Fauci, M.D., the nation’s leading infectious disease expert, said on December 3.
Preliminary laboratory studies, which do not include real-world data, conducted by Pfizer found that antibodies from two doses of its vaccine underperformed against Omicron—but that three doses effectively “neutralize” the variant. Virus-fighting antibodies also increased by 25 times with a third dose.
Research from Moderna showed similar results: Although two doses of its vaccine didn’t provide much protection against the Omicron variant, antibodies increased by 37 times, 29 days after a booster dose. (A full third dose of the vaccine also triggered about 83 times more antibodies than two doses alone.)
Again, the CDC strongly encourages all eligible people to get their COVID-19 vaccines. “Current vaccines are expected to protect against severe illness, hospitalizations, and deaths due to infection with the Omicron variant,” the CDC explains. “However, breakthrough infections in people who are fully vaccinated are likely to occur. With other variants, like Delta, vaccines have remained effective at preventing severe illness, hospitalizations, and death.”
The data shows that the vaccines effectively prevent serious disease—their primary purpose, says infectious disease expert Amesh Adalja, M.D., a senior scholar at the Johns Hopkins Center for Health Security. “The best way to protect yourself against severe disease from Omicron or any other version of COVID-19 is to get fully vaccinated.”
How much protection do boosters offer against Omicron?
Boosters are “definitely advisable” amid the emergence of the Omicron variant, says David Thomas, M.D., professor of medicine at the Johns Hopkins University School of Medicine. Late last month, the CDC strengthened its recommendation that all adults get a booster shot if at least two months have passed since their Johnson & Johnson shot or six months have passed since their final dose of Pfizer or Moderna.
Again, laboratory studies from Pfizer and Moderna found that three doses of their vaccines offer a strong antibody response to Omicron, leading to dozens of times more antibody protection than the standard two doses—suggesting that booster doses are very much worth getting.
“We do know that the boosters increase the overall immune response to SARS-CoV-2, and will provide the best protection as we head into a possible Omicron wave,” says Christine Johnston, M.D., M.P.H., associate professor in the department of medicine at the University of Washington and associate medical director of the UW Virology Research Clinic. And it still offers protection against the life-threatening Delta variant, which experts say might tick up during winter, too.
The boosters currently offered in the United States are the same formulation as the original vaccines—they haven’t changed since they were first approved, with the exception of dosage adjustments for Moderna boosters. But the CDC and the United States Food and Drug Administration (FDA) are in talks with Pfizer, Moderna, and Johnson & Johnson about the possibility of streamlining Omicron-specific boosters, which are already being developed and could be available within months.
“We will learn a lot more in the coming weeks about whether there will need to be an Omicron-specific vaccine,” Dr. Johnston says. “It is reassuring that Omicron specific vaccines are already being developed in case they are needed.” But you shouldn’t wait until then to get your booster—it’s better to be protected now instead of months down the line.
How easily does Omicron spread?
Because of Omicron’s mutations, the WHO says, it poses a higher threat of reinfection—causing COVID-19 in those who have antibodies either through vaccination or a previous SARS-CoV-2 infection—than previous variants of concern. In areas where there is community spread of Omicron, cases are doubling every one and a half to three days, the WHO warns, significantly faster than Delta.
Omicron is now the dominant strain of SARS-CoV-2 in South Africa, where it was first announced, and one early study, which has yet to be peer-reviewed, found that as Omicron spread throughout the country, the number of daily COVID-19 reinfections spiked. “The timing of these changes strongly suggests that they are driven by the emergence of the Omicron variant,” the study says, meaning it could evade antibodies.
This doesn’t necessarily mean it’s time to panic though. Although Omicron is likely more transmissible than previous iterations of SARS-CoV-2, it might cause less severe illness. For example, one of Europe’s biggest Omicron outbreaks so far, a holiday party in Norway where 130 people were infected, has resulted in no hospitalizations.
“It almost certainly is not more severe than Delta,” Dr. Fauci told AFP on December 7. “There is some suggestion that it might even be less severe, because when you look at some of the cohorts that are being followed in South Africa, the ratio between the number of infections and the number of hospitalizations seems to be less than with Delta.”
But these are early reports, and it’s not yet possible to say anything definitive about Omicron; it could appear to be milder than Delta because of skewed data. For example, the attendees of the Norwegian party were vaccinated, meaning they could have had more protection from severe illness than a group of unvaccinated people.
“Personally, I am concerned that one still might get and spread COVID-19 even if vaccinated,” Dr. Thomas says. “Fortunately [the vaccines] can keep you from getting very sick.”
“Similar to earlier in the pandemic, there will be a lot of new data coming out rapidly over the next few weeks as we try to answer the questions about how transmissible Omicron is, the severity of illness caused by Omicron, and how well current vaccines work against Omicron,” Dr. Johnston says.
Until more is known about the variant, there are things people can continue to do to mitigate getting others sick. “We have many known strategies to prevent the spread of SARS-CoV-2, including vaccination—primary series and boosters—masking, distancing, staying home if you have symptoms, testing, and improving ventilation when indoors,” she explains. “We need to continue to use all strategies as we learn more about Omicron.”
This article is accurate as of press time. However, as the COVID-19 pandemic rapidly evolves and the scientific community’s understanding of the novel coronavirus develops, some of the information may have changed since it was last updated. While we aim to keep all of our stories up to date, please visit online resources provided by the CDC, WHO, and your local public health department to stay informed on the latest news. Always talk to your doctor for professional medical advice.
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