Researchers at UW-Madison sequenced different strains of the coronavirus and discovered that Gov. Tony Evers’ “Safer at Home” order from March lowered the number of new COVID-19 cases.
Data collected from Dane and Milwaukee Counties from February through April revealed two different mutations of COVID-19, one from each county. The scientists determined the strain found in Dane County was from Europe, whereas the strain in Milwaukee originated from Asia, according to a UW news release.
By tracking mutations in the virus’s genetic sequences, researchers were able to track the earliest introduction of the strains to the counties, according to UW graduate student Gage Moreno.
“We’ve been sequencing and trying to understand how these viruses relate to one another and where they could have come from around the world,” Moreno said.
Following an analysis of the different virus sample’s genome sequences, little interaction between the two virus strains occurred between Dane and Milwaukee Counties, according to UW-Madison researchers published in the journal Nature Communications.
Other partners who contributed to the research include members from Emory University, the Milwaukee Health Department and Middleton Memorial Veterans Hospital located in Madison.
“We can make comparisons to the genetic variations to what we’re seeing in those other geographic locations,” UW graduate student Katarina Braun said.
By the end of April, Dane County reported 405 coronavirus infections and 19 deaths and Milwaukee County, with just under twice as many residents, recorded 126 deaths and 2,629 cases. The two counties remained distinct in the specific virus strains found in their communities, supporting evidence that Wisconsin’s “Safer at Home” order helped mitigate potential cross contamination of different strains across the state.
“These two communities, that are very close together and share a lot of cultural, political and economic ties, nonetheless had pretty different strains of virus circulating in them,” Thomas Friedrich, one of the authors of the new study and a professor in the UW School of Veterinary Medicine said. “That suggests that the stay-at-home orders, the sheltering in place and the non-pharmaceutical interventions that we put in place at that time were effective in preventing mixing of viral lineages. They kept the two separate.”
Researchers also found that during the state-wide “Safer at Home” order, the number of new COVID-19 cases went down by 40 percent in Dane County and 70 percent in Milwaukee, according to Kasen Riemersma, a postdoctoral researcher and co-author of the study.
By tracking the spread of different strains after the order took effect, researchers saw how effectively the state mandate worked in stopping the spread of COVID-19 by estimating the virus’s basic reproduction number and the expected number of new cases from a single infected person, the news release said.
“With these estimates, we can see ‘yes, the overall estimated total number of infections did decrease after the safer at home order’,” Riemersma said.
Other factors also played a significant role in how successful the virus can spread, specifically the socioeconomic and demographic differences between Dane and Milwaukee Counties.
Milwaukee County’s population lives close together, earns a lower average income and are less likely to have healthcare but more likely to suffer from pre-existing health conditions such as obesity and diabetes. All of these factors can make people more susceptible to contracting coronavirus.
“We couldn’t test a specific link between the social or demographic factors and our data, but we see a strong correlation,” Katarina Braun, a coauthor of the study and UW graduate student. “There’s lots of other literature showing that these human factors are as important, even more important, than viral factors in predicting the spread of this virus.”
Currently, the researchers are studying the outbreak in the UW-Madison dorms that occurred earlier this fall. In the future, they plan on examining case samples from northern Wisconsin.
