The first coronavirus vaccines administered across the country raised hopes for a breakthrough in the fight against COVID-19, but experts are now raising an even more hopeful possibility: people may just need an injection instead of the current regimen. two doses.
The prospect would effectively double the number of vaccine doses available and allow more people to be vaccinated quickly. But the idea has sparked debate, with experts saying that there is still not enough evidence to justify a single dose and that people should plan to take two doses.
The drive to explore the idea of a single-dose vaccine crystallized with a recent New York Times article by Michael Mina, an immunologist at the Harvard School of Public Health TH Chan, and Zeynep Tufecki, a sociologist who wrote extensively about the pandemic.
They called for the immediate start of a new clinical trial to study whether a dose of the vaccine is sufficient. They cited data from tests already conducted for the Pfizer and Moderna vaccines, which showed that protection started after the first dose, with about 90 percent effectiveness, compared with about 95 percent effectiveness after two doses.
There are doubts about how long the protection will last without the second booster dose, but Mina and Tufecki wrote that the possibility of needing just one dose should be studied immediately.
“If that is the case, it would be a game changer, allowing us to vaccinate up to twice the number of people and greatly alleviate suffering not only in the United States, but also in countries where vaccine shortages can take years to resolve ”, They wrote.
Part of the question is how aggressive it should be to push forward with a single dose that may be slightly less effective than two doses, but would spread the protection to twice as many people at a time when an average of about 2,500 Americans are dying from the virus every day and vaccines take months to be widely available.
“What can we do now so that in one month we will not have 60,000 dead?” said Christopher Gill, professor of global health at the Boston University School of Public Health. He said there should be at least a debate about vaccinating twice as many people with a single dose immediately, without waiting for a new test.
“If you wait, you could be dead,” he said.
Scott Gottlieb, former commissioner of the Food and Drug Administration (FDA), questioned the government’s strategy of withholding half the doses to ensure that there is enough for everyone to receive the second dose, since, in the worst case, a single a dose is still at least partially as good.
The administration is withholding 2.9 million doses to serve as the second dose for the 2.9 million people being vaccinated in the first week, instead of distributing all doses at once, said Assistant Secretary of Health and Human Services Brett Giroir.
“We know that the first dose is partially protective, that the data has now been released, so you want to try to inject as many doses as possible to give some benefit to as many people as possible,” Gottlieb, who is now on Pfizer’s board, said on CNBC earlier this month.
Other experts, including those from Operation Warp Speed and the FDA, are rejecting those who aim for a dose, noting that months of careful study have been conducted on the two-dose regimen.
“The second dose is an integral part of the label if vaccines are approved,” Moncef Slaoui, chief scientific adviser to Operation Warp Speed, said at a news conference. “It consolidates patients’ immunity against COVID-19, and these data show lasting immunity, at least in a few months. And I hope it will be very lasting. Therefore, people should not take the vaccine as a single dose vaccine. “
Still, he left the door open for further study. “Someone could ask the question: why not conduct efficacy tests with a single-dose vaccine of Moderna vaccine or Pfizer vaccine?” he added. “That would be a valid question. Of course, time would be quite a challenge. “
Peter Marks, the FDA official who oversees the vaccine review, noted at a separate press conference that the tests and reviews were based on two doses.
“We spent so much time carefully reviewing the data and basing our decisions on science, that it seems pretty daring to just conjecture that a dose might be OK, without knowing it,” he said.
Harvard professor Mina says the United States should conduct a new test to find out for sure, that he said it would take two to three months.
“Even if it is a little lower, from a public health point of view it can be higher,” he said of a dose, meaning that a slightly less effective vaccine spread to twice as many people would help to reduce the general spread of the virus more. quickly.
Moderna said it has no plans for a new test, however.
“We only studied a two-dose regimen and we believe it is highly effective in all age groups with an expectation of durability,” said a spokeswoman for Moderna. “Currently, we don’t plan to study a one-dose regimen.”
Meanwhile, Eric Topol, a professor of molecular medicine at Scripps Research, said it is important to communicate to people that they need to take two doses until more is known.
“The points for studying this are good, but the public message for many for skipping the second dose is worrying when we don’t really know what protection it offers,” he tweeted.
There is also another vaccine in preparation, from Johnson & Johnson, which may have results from its phase three trial early next year. The vaccine uses only a single dose.