every time a person is reinfected by the virus, this risk rises. “this means that even if you’ve had two covid-19 infections, it’s better to avoid a third,” al-aly said. “and if you’ve had three infections, it’s best to avoid the fourth.”
to arrive at their results, the team analyzed roughly 5.8 million de-identified medical records, containing a wide range of ages, races and sexes, maintained by the u.s. department of veteran’s affairs. they narrowed this down to 5.3 million people who did not test positive for the virus between march 1, 2020 and april 6, 2022.
using the same timeframe, they compiled a control group of more than 443,000 people who tested positive for the virus and another group of around 41,000 people who had two or more documented infections. of this 41,000, most people had had two or three infections, a small percentage had four and no one had five or more.
they used statistical modelling to determine the health risks of repeated covid infections in the first 30 days of contracting the illness and up to six months afterwards. they were able to account for multiple covid variants, including delta, omicron and ba.5.
they found that people who experienced multiple covid-19 reinfections were twice as likely to die and three times more likely to be sent to the hospital than those who managed to avoid reinfection. people with multiple infections were also 3.5 times more likely to develop lung problems, three times more likely to suffer heart conditions and 1.6 times more likely to encounter brain conditions than those only infected once.