The T-cell immune response to covid lasts at least six months

SINCE THE beginning of 2020 medical researchers have been in hot pursuit of covid-19. One of their most important goals is to understand the immune response to SARS-CoV-2, the virus that causes it. Finding out what a good response looks like, and how long it lasts, is crucial. The answers will reveal whether people who have recovered from the illness are protected from a second infection, and also indicate how difficult it will be to develop a vaccine.

There is much to worry about. Over the past year, many reports have shown rapidly waning levels of covid-specific antibodies after the initial burst caused by an infection. Antibodies are parts of the immune system that attack the virus directly. They are expected to be involved in any long-term protection against reinfection. If they disappear quickly, that looks, on the face of things, like bad news. Worriers also highlight the facts that immunity to types of coronavirus which cause the symptoms described as “a cold” is short-lived, and that there are already a number of proven cases of reinfection with SARS-CoV-2.