Unvaxxed could get Covid every 16 months

Unvaccinated individuals could expect to get re-infected with Covid-19 roughly every 16 months due to waning immunity, a study has found.

Yale School of Public Health analysed data for coronaviruses similar to Covid-19 including Sars-cov-1 and Middle East respiratory syndrome (Mers-cov), to estimate the likely re-infection rate for Covid-19.

Despite mounting reports of reinfection for Covid-19, the numbers are still not high enough for a Covid study, so scientists analysed data from similar diseases. The research published in the Lancet Microbe this month estimated immunity in those who got Covid-19 weakened fairly quickly.

Yale research associate Hayley Hassler, one of the study’s co-authors, said the risk of reinfection was about 5 per cent at three months after the initial infection, and this rose to 50 per cent after 17 months. People could get re-infected anywhere between three months to five years — with a median of 16 months.

The figures assume that Covid is circulating in the community and restrictions such as masks and social distancing are not observed.

The study also noted immunity could vary significantly among individuals, this could depend for example, on whether the person was asymptomatic, which could produce a weaker immune response than if they did get symptoms.

“Individuals may experience longer or shorter durations of immunity depending on immune status, cross-immunity, age and multiple other factors,” Hassler said.

As the pandemic continues, scientists believe re-infection is likely to become increasingly common. The study notes that maintaining social distancing measures, even for those who have already been infected, and speeding up vaccinations would be critical to preventing deaths.

“Relying on herd immunity without widespread vaccination jeopardises millions of lives, entailing high rates of re-infection, morbidity, and death,” the study stated.

news.com.au