Pfizer and BioNTech said on Wednesday that laboratory tests suggest that three doses of their coronavirus vaccine offer significant protection against the rapidly spreading Omicron variant of the virus.
The companies said blood tests of people who received only two doses revealed much lower levels of antibodies against Omicron compared to an earlier version of the virus. This finding indicates that two doses alone “may not be enough to protect against infection” with the new variant, the companies said.
But blood samples taken from people a month after receiving a booster showed neutralizing antibodies against Omicron comparable to those against previous variants after two doses, the companies said in a statement.
These experiments, performed with laboratory blood samples, cannot say for sure how vaccines will work in the real world. Vaccines stimulate a large-scale immune response that involves more than just antibodies, but antibody levels are the fastest and easiest response to test.
The experiments therefore offer an incomplete picture of how the vaccine will protect against the serious consequences of Omicron. Scientists say it could take a month or more to understand the threat of the new variant as Israel, Britain or other countries with sophisticated health surveillance systems collect more data.
Kathrin U. Jansen, senior vice president and head of vaccine research and development at Pfizer, described the study as small and preliminary. The researchers tested a total of 39 blood samples from people who had received their second or third injection in the previous month.
The results seem to underscore the importance of boosters in fighting infection. President Biden did everything possible to draw attention to the findings on Wednesday, telling reporters they were based solely on a lab report, but were “very, very encouraging.”
âIf you get the booster you’re really in good shape,â he said. According to federal data, the United States has passed more than 200 million people fully vaccinated.
Dr Albert Bourla, Chairman and CEO of Pfizer, said that although two doses may still prevent serious disease from Omicron, “it is clear from this preliminary data that protection is improved with a third dose of our vaccine.” .
Dr Ugur Sahin, CEO of BioNTech, Pfizer’s German partner, said that “a third dose could still provide a sufficient level of protection against diseases of any severity” of the variant.
The companies have suggested that Omicron will not significantly decrease the potency of T cells – another more lasting part of the immune system’s response to coronavirus. Researchers have identified parts of Omicron that can be recognized by T cells produced after vaccination. Most did not contain any mutations.
Company officials haven’t provided data showing how T cells actually behave against the variant; they also did not release the other data, instead summarizing the results in a press release.
In the interview, Dr Jansen said it was “very important” that the parts of Omicron targeted by virus killer cells were mostly unchanged from previous variants. âThis reassures you that you will have enough T cell responses to avoid the worst outcomes,â she said.
Dr Paul Offit, a vaccine expert at Children’s Hospital of Philadelphia and a member of the Food and Drug Administration’s vaccine advisory committee, said he also wished “to reassure.”
“The virus has mutated to the point that it has become less neutralizable by antibodies,” he said. But he said there is no evidence that vaccines have become less effective in preventing serious illness.
âIn all likelihood, two doses of an mRNA vaccine will protect you against serious illness,â he said.
The World Health Organization, which has long resisted large booster vaccine deployments amid severe vaccine shortages in poorer countries, said on Wednesday it was too early to conclude whether vaccines were being delivered. significantly less effective against Omicron or if the emergence of the variant necessitated the people receiving the booster shots the most.
Dr Peter Hotez, vaccine expert at Baylor College of Medicine, called the results “very good news”. But he noted that Pfizer’s experiments did not measure neutralizing antibody levels until a month after the third injection, saying he was concerned about other research suggesting that these levels could drop more sharply later. provided that. Dr Jansen said the researchers were using this blood. samples because they had a very extensive database on them.
The results come a day after a preliminary report of lab experiments in South Africa also revealed that Omicron appeared to blunt the potency of two doses of Pfizer’s vaccine. The South African experiments did not attempt to assess the effectiveness of three doses. The study found that the antibodies produced by people who received two doses of the vaccine were much less effective in fending off infection with Omicron than with previous variants.
Omicron has now spread to dozens of countries, and while the Delta variant is still largely dominant in the United States, the Biden administration is bracing for a new flood of Omicron cases.
While the lab results are an indicator of what’s to come, administration officials say it will take a month or two to get more definitive real-world data from countries like Israel that are closely following every patient.
“We shouldn’t be drawing any definitive conclusions, certainly not until the next two weeks,” Dr Anthony S. Fauci, the US government’s top infectious disease expert, told a White House briefing. Tuesday.
He said early reports from South African medical authorities presented a somewhat optimistic picture of Omicron’s impact. Researchers at a large Pretoria hospital complex reported this week that coronavirus patients are significantly less sick than those they have treated before, and that other hospitals are seeing the same trends.
âWe don’t see a profile of very serious illness,â said Dr Fauci, adding that hospital stays were shorter and patients needed less oxygen. “It could be, and I emphasize perhaps, be less serious, as shown by the ratio of hospitalizations per number of new cases.”
But he noted that South Africa’s population differs from that of the United States, with a high proportion of young people infected, a low percentage of people vaccinated and a high rate of HIV, which can damage the immune system. And others cautioned against drawing conclusions from scattered early reports.
In an interview last week, Dr Bourla said the company started developing a version of its vaccine specifically targeting Omicron right after Thanksgiving and could produce it in large quantities within 95 days. Moderna is on the same path.
“We will be able to switch production overnight,” said Dr Bourla. âIt won’t be necessary to start producing new machines, new equipment, new formulations. “
He noted that Pfizer developed two more prototypes in response to new variants, and neither was found to be necessary because the original vaccine worked against mutations in the virus.
Noah Weiland, Carl Zimmer and Benjamin mueller contributed reports.