New study shows roughly 1.6% of Wisconsinites had COVID-19 antibodies in July

This scanning electron microscope image shows SARS-CoV-2 (orange)—also known as 2019-nCoV, the virus that causes COVID-19—isolated from a patient in the U.S., emerging from the surface of cells (green) cultured in the lab.

MADISON, Wis. — A new statewide study suggests that about 1.6% of Wisconsin’s population had COVID-19 antibodies in July.

The study was conducted by the Wisconsin Department of Health Services alongside the University of Wisconsin School of Medicine and Public Health’s Survey of the Health of Wisconsin (SHOW) and the Wisconsin State Laboratory of Hygiene.

Antibodies indicate if a person has been infected with the coronavirus, regardless of if they experienced symptoms, according to a news release.

“These preliminary study results provide better insight to exposures that may have occurred in the months prior to June and July,” SHOW Director Kristen Malecki said.

The survey for the presence of antibodies throughout the state is designed to test a sample of people three times in 2020 2021, according to Malecki.

The first of the three rounds of testing was completed in mid-August. SHOW and DHS teams are preparing to start the second round in October and the third round sometime this winter.

According to a news release, antibody positivity rates have varied by region in the the state. Antibody positivity rates ranged from roughly 2.6% in the southeast to 0.3% in the western regions.

Malecki said the current results are preliminary. The final results are expected in early 2021.

“There is still much to learn about how long antibodies last in the human body after infection and whether they are protective against future infections,” Malecki said.