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Study Supports Theory Some People Have Built-in COVID-19 Immunity

FILE - An Iranian woman wears a protective face mask and gloves, amid fear of coronavirus disease (COVID-19), as she walks at Tajrish market, March 20, 2020, in Tehran

A study suggests that the common cold could prepare a person’s body to fight COVID-19, a discovery that helps explain why people have such different responses to the novel coronavirus, and could provide clues to fight it.

The study follows a discovery in May, which indicated as many as half the population may have a type of built-in immunity to COVID-19 without ever having had the virus. Scientists reported cases of the phenomena in Britain, Germany, Netherlands and Singapore.

The scientists suspected that this immune “memory” was linked to those people having previously fought off the common cold. A study published Tuesday in the journal Science describes how researchers from the La Jolla Institute for Immunology sought to find evidence supporting this theory.

They examined blood samples taken from healthy subjects collected before the pandemic and examined the T cells in those samples. T cells or, white blood cells, are key parts of the body’s immune system, triggering the antibodies that work to destroy infected cells.

The researchers say T cells remember past infections for decades after a person has had a certain illness. In the samples they examined, they found evidence of T cells “trained” to fight off viruses associated with the common cold. They also were surprised to see that many of the T cells in the sample also recognized COVID-19 without having ever been directly exposed to it.

They suggest this was likely driven by strong similarities between the new coronavirus and the cold-related viruses.

The researchers say this could give certain patients a head start in fighting COVID-19, helping them build a stronger immune response. It may explain why some people get the virus and have few or no symptoms, or do not get the virus at all.

They say there is still a lot they do not know about how this immune “memory” works, but say that it should be targeted in future studies on antibody responses and vaccine development.