A new study from the Yale School of Public Health examined how often a person who is unvaccinated against COVID-19 can expect to contract the virus.

The study, which was published in The Lancet Microbe on Oct. 1, determined that unvaccinated people can be reinfected with the virus about every 16 to 17 months, as reported by The Hill.

Hayley Hassler, a co-author of the study, told Yale Daily News, “The overall goal of the study was to provide an answer to a question that at this point in the pandemic would be impossible to answer empirically, which is how long after you’ve been infected by SARS-CoV-2 can you expect to possess immunity against the virus before you become vulnerable to reinfection?”

Researchers determined there is a short period of natural immunity from the coronavirus, using a model where everyone has either been vaccinated against the virus or infected with COVID-19.

Hassler told Yale Daily News, “Our results are based on average times of waning immunity across multiple infected individuals. Any one of those individuals may experience longer or shorter durations of immunity depending on immune status, cross-immunity, age, and multiple other factors.”

Sudhir Kumar, another co-author of the study and a biology professor at Temple University, told the news outlet that the study reveals that natural immunity is not long-term and is not an alternative for vaccination.

“We need to be very aware of the fact that this disease is likely to be circulating over the long term and that we don’t have this long-term immunity that many people seem to be hoping to rely on in order to protect them from disease,” he added.

The Centers for Disease Control and Prevention reported on Thursday that 57.1% of the U.S. population is fully vaccinated against COVID-19, with 66.1% of Americans receiving at least one dose of the vaccine.

A follow-up paper studying the durability of vaccine immunity against breakthrough infections is expected to be developed in the future, Kumar told Yale Daily News.

Multiple studies have shown that full vaccination prevents infection with symptoms and hospitalisation, for both Alpha and Delta variants Multiple studies have shown that full vaccination prevents infection with symptoms and hospitalisation, for both Alpha and Delta variants Photo: AFP / ISHARA S. KODIKARA