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People who had COVID-19 developed at least 10 times more antibodies after the first dose of the vaccine than the average uninfected person who received two doses, new research shows.
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Another preliminary study found that health professionals who received COVID-19 responded to the first injection in the same way that most people respond to the second.
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The researchers suggested that post-COVID patients may need only one injection to protect them sufficiently from the disease again.
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People generally report more side effects after the second coronavirus injection than the first.
But researchers at the Icahn School of Medicine on Mount Sinai found a slightly different response among patients who already had COVID-19.
These patients not only had stronger side effects – including fatigue, headache, chills, fever and muscle / joint pain – after the first injection, but they also had more antibodies compared to those who had never been sick before.
In a study released on Monday that is still awaiting peer review, the researchers found that people who already had COVID-19 developed at least 10 times more antibodies after the first dose than the average uninfected person who received two doses .
This may mean that previously infected individuals need only one injection to protect them sufficiently from falling ill again. A single injection can also help them avoid more uncomfortable side effects after a second dose.
In fact, the researchers wrote, “changing the policy to give these individuals just one dose of the vaccine” could “save them from unnecessary pain and release many needed doses of vaccine urgently.”
The findings are corroborated by another preliminary study, also released on Monday, which found that healthcare professionals who had previously taken COVID-19 exhibited higher levels of antibodies after the first injection compared to vaccinated individuals who were never infected.
“It was a huge difference. It was something we could easily see,” said Dr. Mohammad Sajadi, an associate professor at the Institute of Human Virology at the University of Maryland School of Medicine, to Insider.
Typically, Sajadi said, patients with COVID-19 develop antibodies about two to three weeks after the initial infection. But it didn’t take long for post-COVID patients to develop antibodies in response to a vaccine: subjects showed high levels of antibodies one week after the first injection, with antibody levels peaking around 10 to 14 days post-vaccination.
But both studies looked at only a small group of vaccinated individuals – a few hundred in total. For this reason, many scientists are afraid to prescribe anything other than the two-dose regimen tested in clinical trials.
“I am a big proponent of the right dosage and the right schedule, because this is how the studies were conducted,” Maria Elena Bottazzi, an immunologist at Baylor College of Medicine, told The New York Times.
Post-COVID patients have a ‘memory response’
Pfizer and Moderna’s advanced-stage clinical trials suggest that vaccines are safe for individuals with a history of coronavirus infections. There are some exceptions, however.
The Centers for Disease Control and Prevention recommend that people with active infection wait until their symptoms disappear – and the standard 10-day isolation period has passed – before being vaccinated. This includes people who have already received their first dose.
“The recommendations for receiving any dose of the vaccine are not to get it if you are downright ill at the moment,” said Dr. Sandra Sulsky, an epidemiologist and director of Ramboll, a global health sciences consulting firm, prior to Insider.
But scientists are still unsure when vaccines are needed for previously infected individuals. Emerging research suggests that antibodies to the coronavirus can last from several months to several years – and even so, antibody levels don’t always correlate with immunity.
All participants in the Sajadi study, for example, tested positive for antibodies to the coronavirus in July and August. When they received the injection, he said, some of them had “very, very low levels” of antibodies – but they still seemed to mount a strong response to the vaccine.
“What this shows is that individuals who have had a previous COVID infection have what we call a memory response or memory response,” said Sajadi. “For most infections, the second time you see that microorganism, you should get a faster response.”
He cautioned, however, that the findings apply only to people with a “common COVID infection” – patients who developed antibodies and recovered from the disease.
A temporary solution for limited doses
Sajadi said that giving only one dose to post-COVID patients is a short-term strategy for dealing with critical vaccine shortages.
With only 32 million Americans vaccinated so far, many states continue to report that they do not have enough doses to meet demand. In recent weeks, some local health departments have even been forced to cancel vaccine appointments or close scheduling sites.
The CDC has now said that vaccination sites can delay the administration of a second dose for up to six weeks – instead of the recommended three to four weeks – in “exceptional circumstances” when it is not feasible to give the second dose in time.
“In times of vaccine shortage, where each dose of vaccine is important, we think the data shows that if you had a previous COVID infection, you may just need a booster dose,” said Sajadi. That “may even be the ideal scenario” for post-COVID patients, when vaccines are widely available, he added.
So far, however, the researchers have examined only how post-COVID patients respond to the Moderna and Pfizer vaccines – both use the same mRNA technology to trigger an immune response.
Sajadi said it is difficult to know whether post-COVID patients will experience an antibody response similar to Johnson & Johnson’s single-dose viral vector vaccine, which it plans to apply for emergency use this week.
“There is no reason to think that it would act any differently,” he said. “But you never know until you test.”
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Originally published