Booster shots targeting SARS virus may help fight Covid variants

People who were infected with SARS in 2003 and recovered are able to produce antibodies that can potentially neutralise all known Covid-19 variants of concern, scientists have found.

The findings, published in The New England Journal Of Medicine, could pave the way for the development of a booster jab, which may involve targeting the SARS-CoV-1 virus responsible for the SARS epidemic in 2003, the Strait Times reported.

A team from the Duke-NUS medical school and the National Centre for Infectious Diseases (NCID), found that the antibodies can also tackle other potential animal coronaviruses, offering a broader spectrum of protection for future variants and coronaviruses.

Among the coronavirus family, one viral sub-group relies on the ACE2 molecule -- a protein found on the surface of many cell types -- to enter human cells. Neutralising antibodies are able to prevent the viral spike protein from binding with the ACE2 molecules in human cells.

"Both SARS-CoV-1 and the SARS-Cov-2 virus, which causes Covid-19, belong to this group, as well as a number of coronaviruses circulating among animals such as bats, pangolins and civets," Professor Wang Linfa from the Duke-NUS Emerging Infectious Diseases (EID) programme was quoted as saying.

"Collectively, this group of viruses is known as the sarbecovirus, which has the potential to jump from animals to humans, and could start the next pandemic, although the exact route of transmission still remains unknown," he added.

The SARS-CoV-1, SARS-CoV-2 viruses, and the sarbecoviruses have similar antibody-binding sites, which can be targeted by a pan-sarbecovirus neutralising antibody to prevent infection.

For the study, the team recruited eight people who recovered from SARS-CoV-1, 10 healthy people and 10 people who recovered from Covid-19 and compared the immune response of the three groups before and after they were vaccinated with the Covid-19 vaccine.

Before getting vaccinated, people who recovered from SARS had detectable neutralising antibodies against the SARS-CoV-1 virus, but had little to no antibodies against the SARS-CoV-2 virus, Dr Wanni Chia, a research fellow at the Duke-NUS EID programme was quoted as saying.

But after taking two shots of the Pfizer Covid vaccine, they displayed high levels of neutralising antibodies against both viruses, and a broad spectrum of antibodies against 10 sarbecoviruses that were examined, she noted.

The team now aims to develop a vaccine booster to increase protection for the Covid-19 variants, and potential SARS-CoV-3 or SARS-CoV-4 disease, the report said.