Patients recovered from COVID-19 ‘mostly protected from reinfection for at least 8 months’
Patients who were previously infected with COVID-19 were about 85% less likely to develop symptomatic reinfection and 80% less likely to develop reinfection in general over the next 8 months, according to researchers.
“Right now, and for the foreseeable future, there is a shortage of COVID-19 vaccine in the world. Despite this, we have been vaccinating people without regard to whether they have already had COVID-19,” Michael B. Rothberg, MD, MPH, vice chair for research in the Medicine Institute of Cleveland Clinic and professor of medicine at Case Western Reserve University, told Healio. “One reason for that is officials have been reluctant to say that having been infected offers protection for more than a few months. We had a database of 150,000 patients who had been tested for COVID-19 — both positive and negative. We realized if we followed those patients forward in time, we could see how much less likely patients who recovered were to test positive for COVID-19 in the future.”
The patients in the study were tested for COVID-19 via PCR starting March 12, 2020, through Feb. 24, 2021. The main outcome was reinfection, which was defined as infection 90 days or more after initial testing.
Results of the study, published in Clinical Infectious Diseases, showed that 8,845 (5.9%) of the patients tested positive and 141,480 (94.1%) tested negative before Aug. 30, 2020. According to the researchers, 1,278 (14.4%) of the positive patients were retested after 90 days, with 62 having a possible reinfection. Of those patients, 31 (50%) were symptomatic. Among patients with initial negative testing, the study showed that 5,449 (3.9%) were subsequently positive and 3,191 (58.5%) of those were symptomatic.
The researchers found that a prior infection offered 81.8% (95% CI, 76.6-85.8) protection against reinfection overall and 84.5% (95% CI, 77.9-89.1) protection against symptomatic reinfection. Rothberg added that this protection increased over time, exceeding 90% between 5 and 8 months.
“Patients who have recovered from documented COVID-19 appear to be mostly protected from reinfection for at least 8 months,” Rothberg said. “Vaccine distribution plans should take this into consideration while supply is limited.”