However, adults 65 and older who were previously infected had only about 47.1 percent protection against a recurrent infection, compared to an 80.5 percent protection rate among young people, the study showed.
The difference can probably be explained by natural changes that weaken the immune system as you age, the study’s authors said.
“We know that as we age, the strength of our immune system decreases,” explains C. Buddy Creech, MD, an infectious disease specialist and director of the Vanderbilt Vaccine Research Program in Nashville, Tennessee. “It is the reason why we donate older adults, herpes zoster boosters and a high-dose influenza vaccine, or influenza vaccine that contains a special immune stimulant called an adjuvant.”
Natural immunity is not enough
The study reinforces the importance of facial masks, social distancing and receiving the COVID-19 vaccine, even for those who have had the coronavirus, especially if they are older. “Natural protection cannot be trusted, especially among the elderly,” wrote the study’s authors.
Coronavirus vaccines that have been authorized in the United States offer significantly better protection than natural immunity, says Creech. “If you consider 100 individuals who have had COVID, their immune response could be across the map,” he says. “It is often related to a variety of factors, including the severity of the initial disease. But when you look at the immune response [to the vaccines], they are much stronger and more consistent. “
In good news, the study found “no evidence” that a person’s immunity decreases within six months after the test is positive for the virus.