The first nationwide coronavirus vaccines have raised hopes of a breakthrough in the fight against COVID-19, but experts now raise an even more promising possibility: that people may need only one shot instead of the current regime. with two doses.
The outlook would effectively double the number of vaccine doses available and allow rapid vaccination of more people. But the idea sparked a debate, with experts saying there is not yet enough evidence to justify a single dose and people should plan to receive two doses.
The impetus for exploring the idea of a single-dose vaccine was crystallized in a recent New York Times issue by Michael Mina, an immunologist at Harvard Public Health School TH Chan, and Zeynep Tufecki, a sociologist who has written extensively on the pandemic.
They called for the immediate start of a new clinical trial to see if a dose of vaccine was enough. They cited data from studies already conducted for Pfizer and Moderna vaccines, which showed that protection started after the first dose, with up to 90% efficacy, compared to about 95% efficacy after two doses.
There are questions about how long the protection will last without the second booster dose, but Mina and Tufecki wrote that the possibility of needing a single dose should be studied immediately.
“If it turns out to be 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 could last for years. days to resolve, “they wrote.
Part of the question is how aggressive it is to push forward with a single dose that might be somewhat less effective than two doses, but would spread protection to twice as many people at a time when an average of about 2,500 Americans die from the virus every day and vaccines are not on the right track to be widely available for months.
“What can we do now to keep 60,000 dead in a month?” said Christopher Gill, a professor of global health at Boston University’s School of Public Health. He said there should be at least one debate about vaccinating twice as many people with a single dose immediately, without waiting for a new trial.
“If you wait, you might be dead,” he said.
Scott Gottlieb, former Food and Drug Administration (FDA) commissioner, questioned the administration’s strategy of withholding half the dose to make sure there is enough for everyone to receive the second dose, given that in worst case, a single dose is still at least partially as good.
The administration retains 2.9 million doses to serve as the second dose for 2.9 million people vaccinated in the first week, rather than implementing all doses simultaneously, said Assistant Secretary for Health and Human Services Brett Giroir.
“We know that the first dose is partially protective, that the data is available now, so you want to try to push as many doses as possible to give as many people a certain benefit as possible,” said Gottlieb, who is now on the board. Pfizer’s administration told CNBC earlier this month.
Other experts, including those from Operation Warp Speed and the FDA, are pushing back those who indicate a single dose, noting that months of careful study of the two-dose regimen have been conducted.
“The second dose is a complete part of the label if the vaccines are approved,” Moncef Slaoui, chief scientific adviser to Operation Warp Speed, told a news briefing. “It strengthens immunity against patients against COVID-19 and these are the data that show long-term immunity, at least in a few months. And I expect it to be very durable. So people should not take the vaccine as a single dose vaccine. “
However, he left the door open for further study. “The question might be, why not conduct efficacy studies with a single-dose vaccine of Moderna vaccine or Pfizer vaccine?” he added. “It simply came to our notice then. Of course, synchronization would be a big challenge. “
Peter Marks, the FDA’s official overseeing the vaccine review, noted at a separate news conference that the studies and reviews were based on two doses.
“We spent so much time carefully examining the data and basing our decisions on science that it seems pretty foolish to assume that a single dose could be OK without us knowing,” he said.
Mina, a Harvard professor, says the United States should conduct a new trial so that it can know for sure, which he said will take two to three months.
“Even if it is slightly lower, from a public health perspective it could be higher,” he said of a single dose, which means that a slightly less effective vaccine spread twice as many people would help reduce the global spread of the virus. faster.
However, Moderna said it has no plans for a new trial.
“We have only studied a two-dose regimen and we believe it is extremely effective in all age groups, with an expectation of sustainability,” said a spokesman for Moderna. “Currently, we do not intend to study a single dose regimen.”
Meanwhile, Eric Topol, a professor of molecular medicine at Scripps Research, said it’s important to let people know that they need to receive two doses until more is known.
“The points for studying this are good, but the public message to many for omitting the second dose is worrying when we don’t really know what protection it offers,” he wrote on Twitter.
There is also another vaccine in progress, from Johnson & Johnson, which could have results from its third phase study early next year. The vaccine uses a single dose.