Most people who have had Covid-19 are protected from catching it again for at least six months, but elderly patients are more prone to reinfection, according to peer-reviewed research published in The Lancet medical journal Wednesday, March 17 evening, CNBC reports.

The first large-scale study on coronavirus reinfection rates was carried out in Denmark in 2020 with the findings confirming that only a small proportion of people (0.65%) returned a positive PCR test twice. PCR tests are seen as the gold standard and tell you if you currently have the virus.

However, while prior infection gave those under the age of 65 around 80% protection against reinfection, for people aged 65 and older it conferred only 47% protection, indicating that they are more likely to catch Covid-19 again.

The authors of the study — which was conducted by researchers from the Staten Serum Institut and the University of Copenhagen in Denmark, and the European Centre for Disease Prevention and Control in Sweden, and received no funding — found no evidence that protection against reinfection declined within a six-month follow-up period.

The coronavirus pandemic has so far caused over 120 million infections and over 2.6 million deaths, according to Johns Hopkins University.