COVID variants can evade antibody immunity all they want—but they’ll still have to reckon with T cells, the oft-ignored and not-as-well-understood other half of the immune system.
While antibodies, specialized proteins produced by the immune system, search for pathogens and incapacitate or destroy them, they don’t last long—typically just a handful of months. They latch on to a specific part of a virus that’s subject to change with new variants, potentially reducing their efficacy.
T cells, a type of white blood cell produced by stem cells in the bone marrow, don’t prevent infection. But they’re capable of dramatically reducing the severity of one, rendering a potentially deadly virus all but mute in some individuals.
Because their response isn’t limited to one specific part of the virus, as is the case with antibodies, they continue to attack, even when the virus mutates and changes shape. And their protection is much more durable, known to last for years, in some cases. Experts say that widespread accumulation of T cells—from vaccine and/or infection—in the population has likely led to generally less severe outcomes for new variants sweeping the country.