A study, published as part of the strong>Centers for Disease Control and Prevention (CDC) s Morbidity and Mortality Weekly Report (MMWR), found that unvaccinated people had 2.34 times greater odds of reinfection compared with fully vaccinated individuals.
The residents were aged 18 or older and had previous COVID-19 infections in 2020 and experienced a second infection between May and June 2021 – the time period that aligns with the emergence and spread of the Delta variant.
"If you have had COVID-19 before, please still get vaccinated," said CDC Director Dr Rochelle Walensky in a statement. "This study shows you are twice as likely to get infected again if you are unvaccinated.
"Getting the vaccine is the best way to protect yourself and others around you, especially as the more contagious Delta variant spreads," she added.
Walensky noted in mid-July that the variant was "spreading with incredible efficiency and now represents more than 83% of the virus circulating the United States”.
MMWR also published a study that pointed to the success of the vaccines in preventing COVID-19 related hospitalisations among the highest-risk age groups.
The second study indicated that the Pfizer and Moderna vaccines in adults aged 65-74 were 96% effective in preventing hospitalisation – a figure that dropped only slightly to 91% in populations aged 75 and older. The Janssen vaccine – produced by Johnson & Johnson – is 85% effective in both age groups.
That effectiveness is still more than double the effectiveness of the average flu shot, which in 2019-2020 was 39% effective.
See more from MedicalBrief archives: