A study by Bellvitge University Hospital, IDIBELL and the Icahn School of Medicine at Mount Sinai in New York, published in the journal Nature Communications, has shown for the first time that the phenomenon of immunological imprinting (recorded when pre-existing immunity against other coronaviruses influences possible immunity against SARS-CoV-2) exists in the case of Covid-19. This is of particular interest given the emergence of new variants emerging of SARS-CoV-2, as well as the potential interactions of pre-existing immunity with vaccines.
Many infections leave an immunological imprinting on the people who affected by them. In the case of some viruses, this immunological memory has an influence and can change the immune response when a subsequent infection occurs with a virus which is somewhat similar to the virus that caused a previous infection. This process is known as immune imprinting and sometimes the influence can be protective, but at other times it can be harmful. The phenomenon is well described in influenza viruses and is also important in immune responses to vaccines.
The collaborative study found that for patients with a more severe disease it took longer to produce neutralising antibodies against SARS-CoV-2. Even more relevant was the finding that previous infections with some coronaviruses (betacoronaviruses OC43 and HKU1, but not alphacoronaviruses such as 229E) leave an immunological memory that conditions the antibody response against Covid-19. This influence appears to be negative, as patients with higher levels of pre-existing immunity against OC43 and HKU1 betacoronaviruses took longer to develop neutralising antibodies against SARS-CoV-2. However, it is not yet possible to assess exactly what its clinical significance is. As a second phase of the work, more patients have been recruited in order to corroborate these first results and to try and establish whether there is a clinical correlation.
The study is the result of the collaboration between the Infectious Diseases Service of Bellvitge University Hospital, IDIBELL and a team of professionals from the Icahn School of Medicine at Mount Sinai in New York. The study included 37 patients admitted for Covid-19 during the first wave of the pandemic at Bellvitge University Hospital. Blood samples were obtained from these patients within the first 24 hours of admission, as well as after three days, after seven days and finally after 46 days. This provided a dynamic characterisation of the humoral (antibody-based) immune response to Covid-19 and allowed to assess the influence that previous immunity to other coronaviruses (which cause the common cold) might have on immunity to Covid-19.