A new study published in the journal Science by researchers of the Francis Crick Institute and University College London has found that some antibodies which develop after infection with common cold coronaviruses, and which remain in the blood for some time, can also target SARS-CoV-2.
The virus responsible for the COVID-19 pandemic, SARS-CoV-2, is part of a large family of coronaviruses. Coronaviruses usually cause mild to moderate upper-respiratory tract illnesses, like the common cold. However, SARS-CoV-2 can cause serious illness and even death. Why people's COVID-19 symptoms vary so greatly isn't fully understood.
The researchers made their discovery while developing highly sensitive antibody tests for COVID-19. They compared the blood of COVID-19 patients with that of patients who had not had the disease. They found that some people have antibodies reactive to SARS-CoV-2 in their blood, despite not ever having been infected with this virus. These antibodies are likely the result of exposure to other coronaviruses, which cause a common cold and which have structural similarities with SARS-CoV-2.
The scientists analysed over 300 blood samples collected before the pandemic, between 2011 and 2018. Nearly all samples had antibodies that reacted with common cold coronaviruses, which was expected. In addition, about 1 in 20 adults also had antibodies that cross-reacted with SARS-CoV-2, and this was not dependent on recent infection with a common cold coronavirus. Among children aged 6 to 16, such cross-reactive antibodies were found much more frequently.
The researchers stressed that there are still many unknowns which require further research. A large study is now underway, in partnership with researchers at Imperial College London and University College London.