Immunity to COVID-19 could last for years, new studies suggest

One-on-one with Dr. Fauci, nation's top infectious disease specialist

FOX TV Digital Reporter interviews infectious disease specialist Dr. Fauci on the latest coronavirus news including booster shots, the MLB All-Star game, vaccine distribution and more.

LOS ANGELES - Immunity created after being infected with COVID-19, in addition to getting vaccinated, could last in the body for years, according to two new studies published this month.

In both studies, one published in the journal "Nature" and the other published online at BioRxiv, authors noted that memory B cells were largely responsible for creating a longer immune response and subsequent immune memory to prevent future infection from COVID-19 and other variants for longer than 6-12 months.

"The data suggest that immunity in convalescent individuals will be very long-lasting and that convalescent individuals who receive available mRNA vaccines will produce antibodies and memory B cells that should be protective against circulating SARS-CoV-2 variants," according to BioRxiv.

The memory B cells enable the body’s immunological memory, which is a defense mechanism to prevent reinfection. The cells enable an individual’s immune system to remember a virus and how to fend it off should the individual become infected with the same disease, according to the National Center for Biology Information.

FILE - Individuals receive a one-dose Johnson & Johnson vaccine on May 19, 2021 in Washington, D.C.

The studies also suggest that the memory B cells in individuals who were previously infected with COVID-19 and vaccinated show evidence of having an extra boost of immunity, creating longer-lasting protection against any future COVID-19 reinfection as opposed to those who were not infected and received the vaccines.

"People who were infected and get vaccinated really have a terrific response, a terrific set of antibodies, because they continue to evolve their antibodies," Dr. Michel Nussenzweig, one of the lead authors in the BioRxiv study, told the New York Times. "I expect that they will last for a long time."

Researchers from the BioRxiv study analyzed blood from 63 people who had recovered from mild COVID-19 about a year earlier. Of those 63 people, 26 had gotten at least one dose of either the Moderna or the Pfizer vaccine.

The antibodies from the vaccine remained in the body and unchanged for about 6-12 months and slowly waned thereafter. But the memory B cells that remained continued to mature and even had the ability to neutralize other COVID-19 variants, according to BioRxiv.

Additionally, in the study published in "Nature," patients who were infected with COVID-19 exhibited trace amounts of leftover antibodies created by the same memory B cells, stored inside bone marrow for future use.

"Blood levels of antibodies fall sharply following acute infection, while memory B cells remain quiescent in the bone marrow, ready to take action when needed," Dr. Ali Ellebedy, one of the lead researchers in the "Nature" study, told the New York Times.

The results of both studies give heath experts renewed hope that the efficacy of the mRNA vaccines being widely distributed will have longevity, potentially longer than 6-12 months.

However, a decision on when a potential booster shot will be necessary remains unclear. Dr. Anthony Fauci, the United States’ leading infection disease expert, told CBS’ "This Morning" co-hosts on May 21, "We don’t know."

"We are planning for the eventuality that we might need to boost people," Fauci said. "We don’t know whether we will have to do it and when we will have to do it. There’s estimates, ‘well it may be a year, it may be a little bit longer,’ the fact is we don’t know."

"But it would really be foolish not to plan for the possibility that we might have to boost people," he added.

Ongoing lab studies assessing durability of the immune response and breakthrough infections will help experts understand whether the shots are necessary, Fauci said.

Pfizer and Moderna have been developing booster shots in a bid to protect against emerging variants, especially a concerning variant first detected in South Africa. While some viral strains have diminished vaccine efficacy, experts believe the existing vaccines remain effective.

FOX News contributed to this report.