Each week, OMRF Vice President of Research Dr. Rod McEver opens “Adam’s Journal” to answer a medical question from Adam Cohen, OMRF’s senior vice president & general counsel and interim president.
The delta variant of the coronavirus is emerging as the dominant strain in the U.S. I’ve read the vaccines appear to provide strong protection against the variant. But what about natural immunity? Are those who’ve recovered from Covid-19 but remain unvaccinated protected from infection by the variant?
Dr. McEver Prescribes
Scientists are just beginning to understand the implications of the delta variant, which was first identified in India. Now the dominant strain there and in the United Kingdom, the variant appears to spread more easily and cause more severe cases of Covid-19 than other mutations of SARS-CoV-2.
For those who are fully vaccinated, the variant may prove to be of little consequence. Early studies show the vaccines approved for use in the U.S. stand up to the mutation. But for those who are betting on natural immunity alone, it could be a different story.
We know that natural infection produces protective antibodies. So far, infection seems to confer less immunity to some variants than vaccination, but levels differ from person to person, and it’s unknown how long it will last.
A recent U.K. laboratory study assessed the risk for reinfection from the delta variant in those who’d recovered from Covid-19. In the study, scientists at Oxford looked at the ability of antibodies in blood samples to neutralize the virus. They found the risk for reinfection with delta variant varied depending on the strain of the initial infection.
But there is good news for those who have recovered from Covid-19. Several studies have shown that when a previously infected person is vaccinated, the immune response that arises is excellent. Against another variant, researchers in Seattle found this so-called “hybrid immunity” generated an antibody response 25 to 100 times higher than natural or vaccine-acquired immunity alone.
Scientists expect the delta variant to be in wide circulation in the U.S. come fall. Even if you’ve recovered from Covid-19 infection, the best protection is vaccination.
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