“Previous studies have reported that 20–50% of people who hadn’t been exposed to SARS-CoV-2 showed T cell responses against different parts of the SARS-CoV-2 virus. To investigate further, a research team led by Drs. Alessandro Sette and Daniela Weiskopf at the La Jolla Institute for Immunology tested blood samples collected between March 2015 and March 2018 for T-cell responses against different pieces of SARS-CoV-2…
[The researchers] found that of the SARS-CoV-2 and ‘common cold’ coronavirus fragments that were most similar (at least 67% genetic similarity) 57% showed cross-reactivity by memory T cells.
‘We have now proven that, in some people, pre-existing T cell memory against common cold coronaviruses can cross-recognize SARS-CoV-2, down to the exact molecular structures,’ Weiskopf says. ‘This could help explain why some people show milder symptoms of disease while others get severely sick.’”
Works of the United States government are not entitled to domestic copyright protection under U.S. law and are therefore in the public domain.