The survey showed that 57 percent of 9,965 individuals who tested between April 23 and June 3 had antibodies, indicating that they were exposed to the Coruna virus.
City health officials said the survey was broad enough to be a reliable indicator for identifying the number of people infected in Bergamo, which has become the epicenter of the epidemic in Italy.
Antibodies were detected in just over 30 percent of 10,404 medical personnel who underwent testing, although they had a greater risk of infection than others.
In a report published in early May, the National Center for Statistics said that the number of deaths in the city rose 568 percent in March, compared to its average between 2015 and 2019, making it the most severely affected by the epidemic in Italy.
Italy recorded about 34,000 deaths and approximately 235,000 cases of Corona virus. The Lombardy region, which includes Bergamo, recorded more than 16,000 deaths.