Immunity may only last for a few months after infection

IMMUNITY to coronavirus among those who have recovered from the infection may only last for a few months, two separate studies have suggested.

Scientists from King’s College London analysed 90 patients and healthcare workers at Guy’s and St Thomas’ NHS Trust and found the level of antibodies in the immune system peaked three weeks after showing symptoms.

In the first longitudinal study of its kind, 60 per cent of participants were found to have a “potent” antibody response while in the throes of the virus, but this fell to 17 per cent after three months. Levels of antibodies depleted by as much as 23-fold in the three-month period after infection and in some people became undetectable.

Boris Johnson has previously said that antibody testing could be a “game changer” and, earlier in the pandemic, the Government considered issuing health certificates to those who had contracted the virus.

The result of the King’s College research, which has not yet been peer-reviewed, raises the prospect that people could be reinfected later.

Researchers in Munich similarly found that those who have recovered could be vulnerable to a second infection. Tests conducted at the Schwabing Clinic on recovered patients demonstrated that the level of antibodies produced by the immune system dropped significantly in a majority of cases.

“In four of the nine patients, we saw sinking levels of neutralising antibodies,” said Clemens Wendtner, the lead researcher.

A study in China also found that the antibody response was not sufficient to create lasting immunity. Doctors at Chongqing Medical University found that the presence of IGG, one of the main antibodies induced through infection, dropped on average by 70 per cent over a three-month period. The results also have implications for the development of a vaccine. Trials in the US by Pfister gave hope that a vaccine could prompt the body into developing antibodies, but many doctors now believe that a successful vaccine will have to do more.

Researchers in Sweden and California say T-cells might play an important role. While antibodies attack a virus before it locks on to a cell, T-cells learn to kill the virus and the infected cell.

It comes as Astrazeneca, the drug manufacturer, prepares to launch a trial in partnership with Oxford University which, if successful, could see elderly people undergo three-minute infusions of antibodies to ward off the virus.