University of Bonn researchers have posted a preprint of their analysis of SARS-CoV-2 infections in Gangelt, Germany. MIT's Technology Review reported last month on the team's early findings that about 14 percent of the town had been infected with the virus, a higher infection rate than anticipated.
The researchers, led by Bonn's Gunther Hartmann, conducted a sero-epidemiological study of the town, which was hard hit by the pandemic likely due to the virus spreading at a Karneval festival. As they report in their preprint posted to Bonn's website, Hartmann and his colleagues collected pharyngeal swabs and blood samples from 919 people living in 405 different households. Based on their immunoassay data, they estimate that 15.5 percent of study participants had been infected with SARS-CoV-2, which they say was five-fold higher than what had been determined from the official number of PCR-positive cases. They also calculated the infection fatality rate to be 0.36 percent.
Hartmann and his colleagues also report that about 20 percent of cases in their cohort were asymptomatic, a result with public health implications. "Apparently one in five infections occurs without noticeable symptoms suggests that infected persons who secrete virus and can infect others cannot be reliably identified on the basis of recognizable symptoms of the disease," co-author Martin Exner from the Institute for Hygiene and Public Health, says in a statement. "Every supposedly healthy person we encounter can unknowingly carry the virus. We must be aware of this and act accordingly."