Immunity to Covid-19 lost within three months of infection, study suggests

Patients who have recovered from Covid-19 may lose their newly gained immunity to the coronavirus within months, according to researchers.

In the first study of its kind, scientists at King’s College London who analysed blood samples from more than 90 patients and healthcare workers found that antibodies which can defeat the virus peaked around three weeks after symptoms first appeared, but then rapidly declining.

This suspected loss of immunity means that the virus “could reinfect people year after year, like common colds”, and “has implications for the development of a vaccine, and for the pursuit of ‘herd immunity’”, says The Guardian.

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“People are producing a reasonable antibody response to the virus, but it’s waning over a short period of time and depending on how high your peak is, that determines how long the antibodies are staying around,” said lead study author Dr Katie Doores.

The study, which is yet to be peer reviewed, was based on results from 65 patients and six healthcare workers at Guy’s and St Thomas’ NHS Foundation Trust who tested positive for Covid-19, as well as 31 staff who volunteered to have regular antibody tests between March and June.

The blood tests revealed that while 60% of the infected participants developed a “potent” antibody response, just 17% had the same potency three months later. “Antibody levels fell as much as 23-fold over the period”, and became “undetectable” in some cases, the newspaper reports.

The findings come as scientists prepare to begin trials of an “antibody treatment that could be used to protect older people from the coronavirus”, The Times says.

The treatment is being developed by Cambridge-based drugmaker Astrazeneca, which hopes that the “three-minute infusion of antibodies could ward off infection for up to six months”, the newspaper reports.

As well as boosting the immune systems of at-risk older people, the therapy would also provide an option for people who cannot use conventional vaccines because their immune systems are compromised by immunosuppressant drugs or chemotherapy.