Up to one in 12 people who have had coronavirus will not develop antibodies – but people who do still have them two months later, research suggests. The NHS has begun rolling out antibody tests, which it is hoped will show who has previously had the virus and whether they have become immune to it. However, scientists are unclear about the degree of protection and how long it lasts, meaning it has not so far been possible to develop “immunity certificates” showing who is protected. The new study shows that Covid-19 antibodies remain stable in the blood of the majority of infected people for almost two months after diagnosis – and possibly longer – but it also found antibodies were not detectable in everyone exposed to the virus. In the study, between two per cent and 8.5 per cent of patients did not develop Covid-19 antibodies at all. Researchers said this could be because the immune response in these patients could have come through other immune response mechanisms, such as different antigens or T-cells. Alternatively, relatively mild infections may be restricted to particular locations in the body that are not picked up in antibody responses.
