The Power of Natural Immunity

Studies show it’s durable and widespread. If you’ve had Covid, you can get by with one shot of vaccine.

By Marty Makary. Dr. Makary is a professor at the Johns Hopkins School of Medicine, Bloomberg School of Public Health and Carey Business School. Excerpts: 

"The news about the U.S. Covid pandemic is even better than you’ve heard. Some 80% to 85% of American adults are immune to the virus: More than 64% have received at least one vaccine dose and, of those who haven’t, roughly half have natural immunity from prior infection. There’s ample scientific evidence that natural immunity is effective and durable, and public-health leaders should pay it heed.

Only around 10% of Americans have had confirmed positive Covid tests, but four to six times as many have likely had the infection. A February study in Nature used antibody screenings in late summer 2020 to estimate there had been seven times as many actual cases as confirmed cases. A similar study, by the University of Albany and New York State Department of Health, revealed that by the end of March 2020—the first month of New York’s pandemic—23% of the city’s population had antibodies. That share necessarily increased as the pandemic spread.

The contribution of natural immunity should speed up the timeline for returning fully to normal. With more than 8 in 10 adults protected from either contracting or transmitting the virus, it can’t readily propagate by jumping around in the population. In public health, we call that herd immunity, defined broadly on the Johns Hopkins Covid information webpage as “when most of a population is immune.” It’s not eradication, but it’s powerful."

"the effect of natural immunity is all around us. The plummeting case numbers in late April and May weren’t the result of vaccination alone, and they came amid a loosening of both restrictions and behavior."

"leading some scientists to suggest that natural immunity is probably lifelong. Because infection began months earlier than vaccination, we have more follow-up data on the duration of natural immunity than on vaccinated immunity."

"After treating Covid for 16 months, we haven’t seen significance incidence of re-infection. In Italy no re-infection clusters have been observed. In a large study from Denmark, less than 0.7% of people who tested positive for Covid, including those who were asymptomatic, ever tested positive again"

"none of the hundreds of variants observed so far have evaded either natural or vaccinated immunity with the three vaccines authorized in the U.S."

"What’s the harm of underestimating or disregarding the protection afforded by natural immunity? It almost certainly cost American lives by misallocating vaccine doses earlier this year, and is still doing so in countries where Covid is prevalent and shots are scarce. It continues to delay full reopening and prolongs the state of fear that has many people wearing masks even when there’s no mandate, or reason, to do so.

Dr. Fauci said last Aug. 13 that when you have fewer than 10 cases per 100,000, “you should be able to open up safely and clearly.” The U.S. reached that point in mid-May."