Most people are naturally armed against COVID-19, study finds

The majority of the people can produce neutralising antibodies against the novel coronavirus in severe cases of COVID-19, according to a study that supports the use of combination antibody therapy to prevent and treat the disease.

The researchers noted that neutralising antibodies that specifically target the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein -- which the virus uses to enter human cells -- are thought to be essential for controlling it.

RBD-specific neutralising antibodies have been detected in convalescent patients -- those who have recovered from COVID-19, according to the team, including researchers from Tel Aviv University in Israel.

Some of the recoverees tend to have robust and long-lasting immunity, while others display a waning of their neutralising antibodies, they said.

The study, published in the journal PLOS Pathogens, used molecular and bioinformatics techniques to compare B-cell responses in eight patients with severe COVID-19 and 10 individuals with mild symptoms, 1.5 months after infection.

B cells of immune sysytem are responsible for mediating the production of antigen-specific immunoglobulin (Ig) directed against invasive pathogens.

The research found that very ill patients showed higher concentrations of RBD-specific antibodies and increased B-cell expansion.

Among 22 antibodies cloned from two of these patients, six exhibited potent neutralisation against SARS-CoV-2, the researchers said.

"Bioinformatics analysis suggests that most people would be capable of readily producing neutralising antibodies against SARS-CoV-2 in severe cases of COVID-19," they noted.

Moreover, the study shows that combinations of different types of neutralising antibodies completely blocked the live virus from spreading.

According to the researchers, these antibody cocktails can be further tested in clinical settings as a useful means to prevent and treat COVID-19.

"Even with a vaccine at our doorstep, arming clinicians with specific anti-SARS-CoV-2 therapeutics is extremely important," the researchers said.

"Combinations of neutralising antibodies represent a promising approach towards effective and safe treatment of severe COVID-19 cases, especially in the elderly population or chronically ill people, who will not be able to so easily produce these antibodies upon infection or vaccination," they added.