Reinfections in covid patients are a very rare circumstance, and when they occur, they hardly have a serious course: the latest study on natural immunity to CoViD-19 comes from Lombardy and delivers good news for once. Even in people most exposed to possible SARS-CoV-2 infection, the protection conferred by a previous infection is prolonged; the fact remains – the researchers point out – that everyone, including the recovered, must be vaccinated.
The percentage of reinfections. The research, which included health data from nearly 15,000 people, was published in the scientific journal JAMA Internal Medicine. In the study, any new infection occurred at least 90 days after the complete resolution of the first infection (to avoid any confusion with previous traces of the virus) was considered “reinfection”. Over 13,000 people among the patients considered by the team of scientists led by Nicola Mumoli, of the Fornaroli Hospital in Magenta, tested negative for the swab, while 1,579 tested positive.
After about a year, 3.9% of those who escaped the virus on the first occasion had in the meantime had the disease. In the group of the healed, only 5 people became ill a second time, 0.31%. Four out of five worked or attended hospital regularly, and therefore had a potentially high risk of coming into contact with the virus. Only one person among the five newly infected needed hospitalization. Natural immunity to covid is therefore very effective for at least a year, and the few reinfections occurred only after a long time from the first infection, on average 230 days later.
Because even the recovered must be vaccinated. However, an editorial commenting on the study underlines the importance of anti-covid vaccination even for the recovered. In fact, the research was conducted before the new coronavirus variants emerged and does not specify how effective the immunity of the recovered is against these versions of SARS-CoV-2. Furthermore, it is unclear how far immunity to covid extends after the considered period, and recent studies show that vaccinated patients develop such comprehensive and comprehensive covid protection that they may no longer need booster vaccinations against covid.
Then there is an aspect of public health that should never be forgotten: achieving population immunity by relying on natural immunity alone is a very painful, not obvious, imperfect process that involves serious loss of life. The only fully eradicated infectious disease in history – smallpox – has been eliminated thanks to vaccines.