How long can natural immunity to COVID-19 last?

A research carried out in Lombardy (Italy) analyzed more than 1,579 people who were infected with the coronavirus between the first months of January 2020 and February 2021. The results showed that reinfections are not common and that the natural protection against coronavirus is long . Furthermore, the authors highlight the importance of vaccination as a booster.

According to the study, it was found that the average time from initial infection to reinfection was 230 days .

"Despite the fact that more than 150 million people have been infected with coronavirus in the world, reinfections are rare ", this was one of the most significant findings during the study that was published by the scientific journal JAMA on May 28. The research aimed to provide a wider perspective on the rate of reinfection in the entire population. Thus the Scientific group analyzed symptomatic and asymptomatic cases of patients of all ages who had been admitted to four hospitals in Lombardy, one of the most affected cities in Italy.

A cohort of 1,579 people diagnosed with the new coronavirus was established, of which only five reinfections occurred, representing 0.31% of the studiend population. Likewise, throughout the evaluation, treatment and follow-up of the patients, it was found that all five were in constant contact with health institutions after the first recovery. One of these five was hospitalized, two of them worked in medical care centers, one received transfusions every week and the last one resided in a geriatric hospital..

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However, another discovery of great relevance during the investigation describes that the interval between the first infection and the second of the patients studied was approximately 230 days. From which it can be inferred that the natural immunity produced by antibodies against COVID-19 after having overcome the disease is about one year .

“The results of the study suggest that reinfections are rare events and patients who have recovered from COVID-19 have a lower risk of getting it again. Natural immunity to SARS-CoV-2 seems to confer a protective effect for at least one year, which is similar to the protection reported in recent vaccine studies ”, states the article published by the journal JAMA.

On the other hand, the analysis was completed before the SARS-CoV-2 variants began to emerge and for this reason it is still unknown how our natural immunity against them will protect us . Meanwhile, researchers suggest that it is essential that all people get vaccinated because, although the immunity produced by antibodies promises to be prolonged, vaccines are the best alternative for collective protection and the end of the pandemic.

“All people should be encouraged to get vaccinated, even if they have previously been infected with SARS-CoV-2. Although unproven, it is possible that the vaccine provides broader immunity to variants than natural infection. And because we do not know how long the protection of the vaccine will last or if there will be variants that escape current protections, we may need immunization boosters or reformulated doses in the future, "the study concludes.