DURBAN – Assumptions of herd immunity to the Coronavirus as more people get infected may be wrong, and patients who have suffered one bout of the virus could face reinfection, according to a new study by British researchers that found that people who recover from Covid-19 tend to lose their immunity within several months.
The findings suggest that, like the common cold and flu, the virus could infect people on an annual basis.
“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 Dr Katie Doores, lead author on the study.
Scientists analysed the immune response of more than 90 patients and healthcare workers at Guy’s and St Thomas’ NHS foundation trust and found levels of antibodies that can destroy the virus peaked about three weeks after the onset of symptoms then swiftly declined.
Blood tests revealed that while 60 percent of people marshalled a “potent” antibody response at the height of their battle with the virus, only 17 percent remained the same potency three months later. Antibody levels fell as much as 23-fold over the period. In some cases, they became undetectable.
The study has implications for the development of a vaccine, and for the pursuit of “herd immunity” in the community over time.
Prof Jonathan Heeney, a virologist at the University of Cambridge, said the study confirmed a growing body of evidence that immunity to Covid-19 is short-lived. “Most importantly, it puts another nail in the coffin of the dangerous concept of herd immunity,” he said.
The study is the first to have monitored antibody levels in patients and hospital workers for three months after symptoms emerged. The scientists drew on test results from 65 patients and six healthcare workers who tested positive for the virus, and a further 31 staff who volunteered to have regular antibody tests between March and June.
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