- A massive coronavirus immunity study indicates that protection against reinfection might last for a lot longer than initially estimated.
- Researchers analyzed various immune response components to COVID-19 for nearly 200 patients, including neutralizing antibodies, B memory cells, and two types of T cells.
- The data shows that these cells can have a long shelf life, potentially providing people years of protection after infection or vaccination.
- Earlier estimates indicated that coronavirus immunity may last less than one year.
We finally have excellent news about coronavirus vaccines. According to the final data, the Pfizer/BioNTech vaccine is 95% effective. Moderna’s interim figures are very close, at 94.5% — final results from Moderna should be available soon. But protection against infection or severe illness isn’t enough if the resulting immunity is short-lived. Now, however, a brand new COVID-19 immunity study provides the best news we’ve seen all week.
Several components of the immune system resulting from exposure to the virus have a long shelf-life, the study shows. It’s not just antibodies that neutralize the spike protein of the virus that can live for a lot longer than believed. It’s the B and T cells, which are crucial to long-term immunity, that have the potential to remain active for years. If the data from this new study is correct, most people will get years of protection against reinfection after contracting the illness or after being vaccinated.
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There’s been a lot of talk about COVID-19 immunity this year, with a flurry of scientific papers delivering great news recently. Some coronavirus antibodies might go away in just three months, but neutralizing antibodies can last between five and seven months. On top of that, a study said that the body’s T cell response to the pathogen could be very “robust,” with T cells detected after six months. These white blood cells specific to the coronavirus can mount a new defense upon reinfection.
This brings us to a new study that’s even broader in scope.
Researchers from La Jolla Institute of Immunology; University of California, San Diego; and Ichan School of Medicine at Mount Sinai studied not just one component of the immune system but all of them for nearly 200 patients. They looked at a COVID-19 survivor’s neutralizing antibody count, T cells, and B cells, and the team concluded that the coronavirus immunity may very well last for years rather than just a few months. If the data can be further verified, this is exactly the good news we need now that the first vaccines are almost ready to be distributed. Surviving the illness or getting a vaccine might result in long-lasting immunity.
The researchers looked at 185 men and women aged 19 to 81 who survived various versions of COVID-19, from asymptomatic to more severe cases. They took blood samples from each survivor and tracked four components of the immune system, including neutralizing antibodies, B memory cells that can create more antibodies, and two types of T cells that can kill cells infected with the SARS-CoV-2 virus.
“If you just look at only one, you can really be missing the full picture,” La Jolla virologist Dr. Shane Crotty The New York Times.
The team found that the levels of neutralizing antibodies were durable, with modest declines over six to eight months after infection. But not all the volunteers in the study had the same levels of antibodies. The T cells only showed a slow decay inside the body, suggesting they have a long shelf life. Surprisingly, the B cells that remember the virus grew in numbers rather than dwindling.
The slow rate of decay is an indication that the cells might survive for a longer time than initially expected, and they could mount a formidable defense upon reinfection.
Even if the neutralizing antibodies disappear after a time, it’s the white blood cells that remember the former encounter with the coronavirus and will put up a fight to prevent serious illness upon reinfection. “Sterilizing immunity doesn’t happen very often — that is not the norm,” La Jolla’s immunologist Dr. Alessandro Sette told The Times.
If the research is accurate, the immune system would destroy the pathogen upon reinfection before it has time to do any damage. “It may be terminated fast enough that not only are you not experiencing any symptoms, but you are not infectious,” Sette said.
While the researchers can’t say for certain how long coronavirus immunity will last in light of these findings, the data indicates that it might be years until immunity is lost. Whenever talking about coronavirus immunity, researchers or reports like to mention that some of the people who survived SARS in 2003 had immunity that lasted up to 17 years. Some speculated that the same might happen with SARS-CoV-2, SARS’s successor.
“That amount of memory would likely prevent the vast majority of people from getting hospitalized disease, severe disease, for many years,” Crotty said of the data.
Still, some of the infected people in the new study did not have a long-lasting immunity after recovery. It’s unclear why, but there have been cases of true COVID-19 reinfections, so that’s also a known possibility. However, that’s where vaccination might help people mount an even more effective immune response.
The new study has not been peer-reviewed. Like all coronavirus research, it could benefit from additional data and we’ll probably get much more info in the coming months. But if coronavirus immunity does last several years, the world might have a chance not only to end the pandemic but eradicate the illness through ample immunization campaigns with highly effective vaccines. That said, many public health experts think the virus might never go away. Instead, COVID-19 might become endemic, just like the flu.