Natural COVID Immunity vs Delta Variant: Is It Enough To Protect You?

As the Delta variant continues to account for the vast majority of cases of COVID in the United States, Google Trends data shows users are asking if natural immunity could protect against what is proving to be the most virulent strain of the virus.

The U.S. Centres for Disease Control and Prevention (CDC) currently estimates that the Delta variant is behind as much as 99.8 percent of the country's total COVID cases.

Experts predicted that this form of COVID would overwhelm other variants such as Mu in the U.S., just as it did with Alpha in the U.K., and that appears to have occurred.

However, the dominance of Delta does not mean that a different approach is needed to tackle it, experts have told Newsweek. That includes relying on natural immunity, which the CDC describes as immunity "acquired from exposure to the disease organism through infection with the actual disease."

Dr. Sabrina Assoumou, an infectious diseases physician at Boston Medical Center, cautioned against relying on natural immunity as protection against COVID. "There are still questions about the protection of natural immunity against variants," she told Newsweek. "A recent study showed that the likelihood of re-infection was higher among unvaccinated persons when compared to vaccinated individuals."

The CDC study that Assoumou referred to shows that individuals in Kentucky who had already had COVID and had not been vaccinated against the virus were over twice as likely to be reinfected in comparison with people who were fully vaccinated.

Dr. Peter Chin-Hong, professor of medicine at UCSF and an infectious disease physician in San Francisco, California, also warned against relying on natural immunity to protect against COVID.

He told Newsweek: "Natural immunity is a good thing in general and can be robust in many people." Chin-Hong said that the trouble with relying on natural immunity is that it could vary from person to person, and there is no telling how long it may last. The effectiveness of natural immunity can depend on when a person was infected, he said.

In addition, natural immunity may not protect well against all variants of COVID. A person infected with a new variant may not have immunity from a previous infection with a different strain of the virus.

Attempting to rely on natural immunity to tackle a virus is not a new concept that has emerged during the COVID pandemic, he said. "We had the same argument recently with the varicella vaccine in children versus whether you should just allow kids to get chickenpox 'naturally.'

"People have even had chickenpox 'parties' where a kid with chickenpox will interact with other kids who come over to get exposed and then acquire chickenpox and the corresponding immunity naturally."

He said this approach has serious drawbacks. "Chickenpox can sometimes cause more severe disease like pneumonia and kids with natural chickenpox are not happy campers, plus they have to miss school. The vaccine is so much better."

Dr. Assoumou said the best course of action in protecting against Delta is the one already being employed: vaccination.

Vaccination provides a "high level of protection" against COVID, she said. "We know that the current vaccines that are authorized or approved in the U.S. all work well against the Delta variant. Vaccination is also recommended for individuals who have recovered from COVID-19."

Chin-Hong echoed this sentiment: "The best protection against Delta is science. And of course, vaccines. One million percent."

Pfizer Vaccine
A dose of the Pfizer COVID vaccine is prepared in Bangkok on October 4, 2021. Experts warn that the vaccine offers much better protection against COVID than natural immunity. LILLIAN SUWANRUMPHA/Getty