People who have had COVID-19 only need one coronavirus vaccine shot

• A single shot of Pfizer or Moderna’s vaccine provides high protection for people who have had COVID-19.
• This is probably because their bodies are responding to a viral threat they have seen before.
• Giving a second dose to people who have had COVID-19 is a kind of waste, ‘said one expert.
• Visit the Insider Business Department for more stories.

In the race to get coronavirus vaccines into their arms as quickly as possible, scientists believe they have found a way to speed up the process: give people who have had COVID-19 just one dose.

Most Americans who are eligible for vaccines receive Pfizer or Moderna’s vaccine, both of which require two doses that are administered several weeks apart. But a growing chorus of researchers agree that a single dose of one of the vaccines will elicit an adequate immune response among people who have already had the coronavirus. Research suggests that it is a good chance to give them the second dose.

“For those who are infected and recovered, who are tens of millions of people, they will only need one shot, which will make the vaccine go even further,” said Dr. James Hildreth, president of Meharry Medical College, told Insider. .

Hildreth serves on the Food and Drug Administration Advisory Committee, which recommends all three authorized coronavirus vaccinations in the United States. The third, from Johnson & Johnson, is a one-shot vaccine, so people who have had COVID-19 will get a single dose of it, no matter what.

Since more than 29 million Americans had COVID-19, it could be up to 15 million Pfizer or Moderna shots that could go to other people.

New research supports one-shot strategy

Once someone has had COVID-19, their immune system must recognize the virus when it re-enters. So if a vaccine stimulates the body to start producing antibodies again, it is logical that the immune system will cause a stronger and faster defense.

In a letter in the New England Journal of Medicine on Wednesday, 32 researchers from the Icahn School of Medicine on Mount Sinai wrote that a single-dose strategy for people who already had the virus “should require investigation.”

The team found in a small study that people who previously had COVID-19 developed ten to 45 times as many antibodies after their first dose of Pfizer or Moderna’s vaccine as the average uninfected person. The research is still awaiting peer review.

“The first dose ultimately acts as a booster,” said Dr. Jeremy Faust, an emergency medicine physician at Brigham and Women’s Hospital, told Insider. “If you are infected, it is very likely that one dose will be very good for some time.”

However, there are some caveats: people may need to confirm that they still have antibodies if they were ill a while ago, because the antibody levels decrease over time. An antibody test is also needed for those who suspect they have COVID-19 but have never tested positive. If the antibody test returns positive, the second chance is probably superfluous.

“What’s the point?” Akiko Iwasaki, an immunobiologist at Yale University, told Insider. “It’s a wasted shot.”

‘This is where policy leaves science behind’

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France has started recommending a single dose of vaccine for people who had COVID-19 in February.

By that time, the Mount Sinai investigation was out, and another preliminary study also revealed high antibody levels among health workers who had COVID-19 before they got their first chance.

Dr Mohammad Sajadi, a co-author of the study, told Insider that COVID-19 patients usually develop antibodies two to three weeks after their initial infection. But the health workers showed high antibody levels a week after their first shot.

“What you are showing is that individuals who have had a previous COVID infection, which we call a recall reaction or a memory reaction,” Sajadi said. organism sees, responds faster. “

In late February, a UK study found approximately equal antibody levels among people who received the first dose of Pfizer vaccine and had never received COVID-19 and those who had COVID-19 but had not yet been vaccinated. After the people who had COVID-19 got their first shot, their antibody levels were 140 times higher than their peak levels before the vaccine.

Yet most countries, including the US, do not yet recommend a single-dose regimen for people who have had COVID-19.

“This is where policy leaves science behind,” Iwasaki said.

Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told NBC News in February that the idea was worth considering.

“The data looked really impressive – if you’re infected and then get a single dose, the boost you get with the single dose is enormous,” Fauci said. “This is one thing you might want to consider, but we really want to examine the data carefully first.”

Concerns about long-term immunity

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Since scientists have not yet had much time to follow up on the vaccine recipients, there is still no consensus on how long the immunity induced immunity lasts. This uncertainty is one of the reasons why experts are reluctant to advocate anything other than the standard two-dose regimens of the Pfizer and Moderna vaccines.

Postponing or skipping the second dose puts a lot of pressure on the first dose to provide solid, long-term immune protection, Princeton University researchers wrote Tuesday. They expressed concern that enabling the dosing regimen could lead to a “wide range” of vaccine outcomes.

But Iwasaki said people who had COVID-19 could probably wait months before they got their second chance – if they needed one at all.

“It’s simply not necessary to do it so early,” she said.

Scientists are also optimistic that T cells, although known to decrease antibody levels over time, provide long-term protection for those who have had COVID-19. Like antibodies, T cells have impressive memory forces that can help the immune system recognize and attack the coronavirus again.

A recent study found that people who had COVID-19 before had a stronger T-cell response to one shot of Pfizer’s vaccine than people who had never been infected.