The Associated Press25 December 2020 10:18:41 IST
Two new studies provide encouraging evidence that having COVID-19 may offer some protection against future infections. The researchers found that people who produced antibodies to the coronavirus were far less likely to test positive again for up to six months and possibly longer. The results bode well for vaccines, which cause the immune system to produce antibodies, substances that attach themselves to a virus and help it eliminate it.
Researchers found that people with antibodies to natural infections were “at much lower risk … in the order of the same kind of protection you would get from an effective vaccine,” of contracting the virus again, said Dr Ned Sharpless. , director of the National Cancer Institute of the United States.
“It’s very, very rare” to be reinfected, he said.
The institute’s study has nothing to do with cancer – many federal researchers have switched to coronavirus work due to the pandemic.
Both studies used two types of tests. One is a blood test for antibodies, which can persist for many months after infection. The other type of test uses nasal or other samples to detect the virus itself or parts of it, suggesting a current or recent infection.
A study, published Wednesday in the New England Journal of Medicine, involved more than 12,500 healthcare workers at Oxford University hospitals in the UK. Of the 1,265 who had antibodies to the coronavirus at the start, only two had positive tests to detect active infection over the next six months, and neither developed symptoms.
This contrasts with the 11,364 workers who initially did not have antibodies; 223 of them tested positive for infection in the following six months.
The National Cancer Institute study involved more than 3 million people who performed antibody tests from two private laboratories in the United States. Only 0.3% of those who initially had antibodies subsequently tested positive for the coronavirus, compared with 3% of those who did not have such antibodies.
“It’s very gratifying” to see that the Oxford researchers saw the same reduction in risk – 10 times less likely to have a second infection if the antibodies were present, Sharpless said.
His institute report was posted on a website scientists use it to share research and is under review at a major medical journal.
The findings “aren’t a surprise … but they’re really reassuring because they tell people immunity to the virus is common,” said Joshua Wolf, an infectious disease specialist at St. Jude Children’s Research Hospital in Memphis who hasn’t played no role in any of the studies.
The antibodies themselves may not provide 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 exposure to the virus, he said.
“We don’t know how long this immunity is,” Wolf added. Cases of people receiving COVID-19 more than once have been confirmed, so “people still need to protect themselves and others by preventing reinfection.”