IIn an extraordinary moment, British health authorities are taking extraordinary measures to defeat Covid-19. But some experts say that in doing so, they are also making a serious bet.
In the past few days, the British said they would extend the interval between administering the two doses required for Covid-19 vaccines already in use – potentially up to three months, instead of the recommended three or four weeks. And they said they will allow the first and second doses for anyone to be from different vaccine manufacturers, if the corresponding vaccine is not available.
The measures were born out of a desire to start vaccinating as many people as soon as possible, especially with Britain experiencing high levels of transmission in an apparently more infectious form of SARS-CoV-2, the virus that causes Covid- 19.
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But they are also effectively turning that country into a living laboratory. The moves are based on small pieces of evidence extracted from “subsets of subsets” of participants in clinical trials, as an expert described for STAT, and on general principles of vaccinology, rather than actual research on the specific vaccines being used. If the efforts are successful, the world will have learned a lot. If they fail, the world will also have gained important information, although some fear that it could be costly.
American health officials have ruled out the possibility that the United States will follow Britain’s lead, with Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, saying that the vaccines in use – one made by Moderna, the other by the Pfizer partnership and BioNTech – will be implemented here using schedules which were tested in Phase 3 studies that generated evidence that the Food and Drug Administration authorized vaccines for emergency use.
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Although the data from both suggests that vaccines begin to protect about 10 or 12 days after the first dose, it is not known how long this initial protection lasts. In clinical trials, the levels of neutralizing antibodies, which are believed to play a critical role in protecting against infection, were not substantial after the first dose of the Pfizer vaccine.
“Although we think that a single shot could provide protection for more than four weeks, we just don’t know it. We don’t know when it will fall, ”said John Mascola, director of the NIAID Vaccine Research Center. Mascola said Operation Warp Speed, the federal government’s project to speed up Covid’s vaccines, ruled out changing vaccination schedules before Britain decided to do so.
Paul Bieniasz, of Rockefeller University, is one of those who dreadfully observe the evolution of the situation in Britain. A retrovirologist who left HIV research to work on SARS-2, Bieniasz is studying how the virus acquires mutations that allow it to avoid the protective antibodies that people develop when they get Covid-19 or are vaccinated against it.
Bieniasz believes that Britain is replicating in people the experiments it is doing in its laboratory – and may be promoting vaccine-resistant forms of the virus.
On New Year’s Day, he posted a short and sarcastic treatise – “Reflections on an anonymous and angry virologist” – on Twitter describing how someone could make Covid’s vaccines “impotent”, if that were his goal. Giving millions of people who are at daily risk of contracting the disease incomplete protection by postponing the second dose of the vaccine was key, he suggested.
“My concern, as a virologist, is that if you wanted to make a vaccine-resistant strain, what you would do would be to build a cohort of partially immunized individuals on the teeth of a highly prevalent viral infection,” Bieniasz told STAT. Even launching the vaccine when there is so much transmission occurring is far from ideal, he said, suggesting that it would have been safer to eliminate the amount of virus in circulation before starting the vaccine implantation.
“You are essentially maximizing the opportunity for the virus to learn about the human immune system. Learn about antibodies. Learn how to avoid them, ”he said.
Isabella Eckerle, a coronavirus researcher at the Geneva Center for Emerging Viral Diseases, shares Bieniasz’s concern that Britain is increasing the potential for so-called escape mutants. She understands the public health imperative behind this approach, but is concerned with having a large number of people partially protected for several months in a row. Britain is vaccinating its older citizens first. The immune system of the elderly does not work as well as that of younger adults; some will inevitably contract Covid pending the second dose of the vaccine, she said.
Reports of partially vaccinated people who contracted Covid can also undermine confidence in vaccines, Eckerle said: “If we don’t use this vaccine properly, it will damage the entire field of vaccinology for many, many years, I think.”
Stephen Goldstein, a virologist at the University of Utah who specializes in coronavirus, said that taking Britain’s approach at a time of limited vaccine supply could create other problems.
“If we vaccinate everyone with one dose and … six weeks later, the efficacy is now 30% and we don’t have the doses to increase them at that point because we use your second doses in another round of first doses, it is potentially a disaster” , he said.
Not everyone agrees that a disaster is brewing. Some believe it makes sense, given the increase in cases in Britain and the rapid spread of variant B.1.1.7, which studies suggest may be 50% more transmissible than the viruses it is rapidly replacing.
“Deep down in my being, I really wish we could follow the original vaccine schedule, because that’s the safest thing to do,” said Akiko Iwasaki, a virologist and immunologist at Yale University who tweeted about her support for the British approach. “But looking at what’s going on in the world and just looking at the bad implementation and distribution situation, I’m feeling frustrated that we need to find other options.”
(Iwasaki was dismayed, however, upon realizing Britain’s instructions to doctors that they could use a second dose of unmatched vaccine if that were their only option not made in the context of a clinical trial. Although there is reason to this believes that boosting with a different type of vaccine may actually be useful in some cases – particularly if the first dose is a vaccine like the AstraZeneca vaccine that uses a harmless virus into which the SARS-2 genetic material has been fused – the approach has not been studied in clinical trials.
“They are missing out on the opportunity if they are doing it at random and not even tracking the effectiveness of this combination,” said Iwasaki. “Yes, I am much more comfortable if it is a kind of test.”)
Rajeev Venkayya, president of global vaccines at Takeda Pharmaceuticals, also believes that Britain’s decision to extend the interval between doses of the vaccine is “justified”.
“Of course, we would all like to see vaccines used exactly as they were tested in the Phase 3 efficacy tests. I don’t think there is any debate about that. The question is, do you have evidence to support flexibility? And here, I really think – and this is specific to the AstraZeneca vaccine – it looks like there is additional evidence that can support a modified recommendation, ”said Venkayya, who served as special assistant to President George W. Bush and senior director for biodefense. In this role, Venkayya was the person responsible for the White House in efforts to prepare for a pandemic triggered by the spread of H5N1 avian flu.
While the US-based trial of the AstraZeneca vaccine is testing two doses administered four weeks apart, studies the company has conducted elsewhere have given some participants the two doses at intervals of six to eight weeks, or nine to 11 weeks , and some received doses more than 12 weeks apart.
The Pfizer and Moderna vaccines are the first to use mRNA technology, and companies have not studied these extended dosing schedules. Pfizer objected to the proposal that the vaccine be used with a longer interval between vaccinations.
Venkayya, whose thinking is influenced by his years at the White House, said that sometimes politics must be done without perfect data.
“I think that in order to take the standards that we normally apply to the body of evidence we require before making decisions and recommendations on how to use vaccines, this of necessity has to change in the midst of a crisis like this,” he said. “I think there is the way we do medicine and public health in times of peace … where we have the luxury of using the time we need and investing resources and efforts to collect enough data to reach a conclusion. You just don’t have that luxury in the middle of a crisis. “