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There’s Good News About Your Immune System and the Coronavirus
When antibody levels go down, T cells have your back
More than any other facet of Covid-19, the question of immunity has been a stressful source of good news/bad news whiplash.
Good news: Scientists discovered early on that most people who have been infected with SARS-CoV-2 (the official name for the novel coronavirus) create virus-specific antibodies — special proteins produced by immune cells that help fight off the coronavirus and provide immunity against future infections. This finding helped guide the dozens of vaccines currently under development.
Bad news: Those antibodies may hang around for only a couple months, a phenomenon called waning immunity. There have been anecdotal accounts of a few people potentially contracting the virus a second time, and a new preprint paper — which has not yet been peer reviewed — showed that in some recovered patients, antibody levels declined to undetectable levels after three months. These reports have caused some people to speculate that a vaccine will be largely ineffective and that we may never develop herd immunity to the virus.
Before you start to doom spiral, though, let’s turn back to good news: Antibodies aren’t the only tools the immune system has to fight repeat invaders. Several recent studies have shown that in addition to antibodies, people also develop virus-specific T cells. These immune cells are an important component of long-term immunity, and in some cases they’re detectable in the body many years after antibodies dissipate. But because nothing is simple with SARS-CoV-2, the T cells produced in response to the coronavirus are a little unusual.
B cells and T cells work as a team
The immune system has two waves in its defense against an invader: the initial innate response, which looks the same for pretty much any attacker, and the slower adaptive response, which takes about a week to develop but is tailored to the current assailant. The adaptive response also serves as a type of immunological memory, so that if the same virus tries to reinfect a person, their immune system can kick into gear and immediately mount a virus-specific defense. It’s this second phase that scientists…
