Two new studies provide convincing evidence that COVID-19 may provide some protection against future infections
The results are good for vaccines, which make the immune system produce antibodies – substances that bind to a virus and help with its elimination.
The researchers found that people with antibodies from natural diseases were “at a much lower risk … on the order of the same kind of protection you would get from an effective vaccine,” from getting the virus again , said Dr. Ned Sharpless, director of the U.S. National Cancer Institute.
“It’s very rare” to respond, he said.
The institute ‘s study had nothing to do with cancer – many federal researchers have switched to coronavirus activity because of the pandemic.
Both studies used two types of test. One is a blood test for antibodies, which can last for several months after infection. The other type of test uses nasal or other samples to detect the virus itself or parts of it, suggesting a routine or recent infection.
One study, published Wednesday by the New England Journal of Medicine, involved more than 12,500 health workers at Oxford University Hospitals in the United Kingdom. Among the 1,265 who had initial coronavirus antibodies, only two had good results in tests to detect active infection in the following six months and none developed symptoms.
This differs from the 11,364 employees who did not initially have antibodies; 223 of them were positive for infection in the following six months.
A National Cancer Institute study included more than 3 million people who received antibody tests from two private laboratories in the United States. Only 0.3% of those who first had antibodies tested positive for the coronavirus, compared with 3% of those who did not have such antibodies.
“We’re delighted to see that Oxford researchers have seen the same risk reduction – 10 times more likely to get a second infection if antibodies were present,” said Sharpless.
His institute’s report has been posted on a website that scientists use to share research and is under review at a major medical journal.
The findings are “not surprising … but it’s very encouraging because it tells people that immunity to the virus is common,” said Joshua Wolf, an infectious disease specialist at St Jude’s Children’s Research Hospital in Memphis at which was not part of either study.
Antibodies themselves may not provide the protection, they may just be a sign that other parts of the immune system, such as T cells, are able to fight off any new exposures to the virus, he said.
“We don’t know how long this immunity will last,” Wolf said. Cases of people receiving COVID-19 more than once have been confirmed, so “people still need to protect themselves and others by preventing relapse.”
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