Study finds 95% of COVID survivors protected from reinfection for at least 8 months, if not more

Study examined immune memory to the virus
Coronavirus testing
Posted at 5:44 PM, Jan 12, 2021
and last updated 2021-01-12 21:34:33-05

SAN DIEGO (KGTV) — It’s the question on the minds of many COVID-19 survivors: how long am I protected from getting this virus again?

A new study from a team at the La Jolla Institute for Immunology is offering the clearest answer yet, and the results are being hailed as “good news.”

Researchers tracked a group of COVID-19 survivors for up to eight months after their infection, and found about 95 percent had strong levels of bespoke immune cells specially tailored to fight SARS-Co-V2.

Their findings suggest the vast majority of COVID-19 survivors have the immune cells needed to fight reinfection for at least eight months and potentially much longer, based on projections from the data gathered so far.

“It certainly looks like there’s going to be immune memory for multiple years and it wouldn’t be surprising for there to be substantial immune memory for ten years,” said study co-author Dr. Shane Crotty, an LJI professor.

The team measured the levels of antibodies, memory B cells and two kinds of T cells in the blood of 188 COVID-19 patients, many of whom were located in San Diego.

This was the largest study of its kind to measure all four components of immune memory for any virus, Dr. Crotty said.

“The results for almost all the metrics we did were better than we had hoped for,” he said.

Although other studies have shown a potentially concerning decline in COVID-19 antibodies over time, the researchers at LJI showed other bespoke immune cells continued to stand guard in the body, ready to sound the alarm and call in reinforcements should a patient encounter the virus again.

"Our data suggest that the immune response is there—and it stays," said study co-author Dr. Alessandro Sette, another LJI professor.

The findings suggest about five percent of participants produce a weakened immune memory response. Dr. Crotty suspects a fraction of the five percent is susceptible to a second infection, but said further research is needed to get a more precise estimate.

The study comes on the heels of another paper on UK healthcare workers published in December that found COVID-19 antibodies offered protection for at least six months, if not more.

The researchers at JLI examined patients who were infected with the real virus, what’s known as a natural infection, but their findings do offer an encouraging clue for the staying power of the vaccines.

“If the memory looked really strained, that would be a red flag for the vaccines,” Crotty said. “That would say there might be something particularly unusual about spike.”

Spike is the name of the coronavirus’s signature spike-like protein. The vaccines developed by Pfizer and Moderna instruct the body to build a simulated version of the spike protein to train the immune system.

The LJI findings “are good signs for the vaccine, but the vaccines are not the infection,” Crotty said. He noted that the body responds to vaccines differently than it responds to natural infections. Some vaccines confer longer-lasting protection than a natural infection; with other vaccines, the immunity doesn’t last as long.

He said vaccine-makers will need to continue studying inoculated patients to truly understand how long vaccine protection will last.

Meantime, the LJI team plans to continue to measure immune memory in the patients with natural infections and update its findings periodically. With each update, researchers will have a more accurate sense of how long protective immunity may last, Crotty said.