Antibodies might not be sole proof someone has recovered from COVID-19

Antibodies to the novel coronavirus should not be considered the only evidence that someone has recovered from COVID-19, researchers say.

They studied nine confirmed coronavirus patients from seven families, along with eight of their household members who later became ill with COVID-19 symptoms.

The original patients all developed antibodies to the virus, as shown by blood tests after they recovered.

The relatives who got sick, however, had negative antibody tests, but six of the eight had other immune cells in their blood that suggested they had been infected. For up to 80 days after their symptoms began, they had T cells – a key component of the immune system – that could recognize and target the coronavirus.

“T cell responses may be more sensitive indicators of SARS-Co-V-2 exposure than antibodies,” the researchers said on Monday in a not-yet-peer-reviewed paper.

“Our results indicate that epidemiological data relying only on the detection of SARS-CoV-2 antibodies may lead to a substantial underestimation of prior exposure to the virus.”