SIOUX FALLS, S.D. (KELO) — The Sturgis Rally, an annual motorcycle rally in the Black Hills, was a coronavirus spreader and study of cases in Minnesota shows, a newly released report by the Centers for Disease Control says.

“Eighty-six Minnesota COVID-19 cases were associated with the South Dakota motorcycle rally; approximately one third of counties in Minnesota reported at least one case epidemiologically linked to this event,” said the study called COVID-19 Outbreak Associated with a 10-Day Motorcycle Rally in a Neighboring State — Minnesota, August–September 2020.

Cases were identified in people who worked at the rally and attended the rally and then, spread COVID-19 to others.

The numbers linked to the Sturgis Rally may seem small compared to the 461,000 attendees and the number of COVID-19 cases in Minnesota 249,906 as of Nov. 20, but the findings show how one large event can spread the virus, according to the CDC.

Genome sequencing identified links between rally attendees and rally workers and others. Genome sequencing is used to identify the virus genetic characteristics and its transmission.  Six genetically similar clusters For example, a rally worker at a restaurant and two other people who got the coronavirus in the cluster visited that restaurant.

“These findings support current recommendations for mask use, physical distancing, reducing the number of attendees at gatherings, isolation for patients with COVID-19, and quarantine for close contacts to slow the spread of SARS-CoV-2 (1),” the report said.

This CDC report is not the first on the link between COVID-19 transmission and the Sturgis Motorcycle Rally. A September report from IZA Institute of Labor Economics linked 266,796 COVID-19 cases to the Sturgis Motorcycle Rally. South Dakota health officials said the report’s numbers were not matching data collected by the state and Gov. Kristi Noem called it “grossly misleading” in a statement released by her office.

Forty-one of the 86 COVID-19 individuals had an average of 2.5 close contacts while they were infected. Seventeen of 48 interviewed COVID-19 individuals said they had a close contact at work

Attendees with COVID-19 spread it to household members and to the work place. Secondary transmission was traced to two workplace outbreaks one wedding outbreak and one funeral outbreak, according to the CDC.

Sixteen of the 48 individuals interviewed by health officials reported working while infectious including five who worked at the rally and four who worked in health care after returning from the rally.

The Minnesota Department of Health and local health officials interviewed 80% of the confirmed COVID-19 cases to gather and trace the extent of the impact.

While individuals with COVID-19 may not have symptoms, 74% of the COVID-19 patients in this study said they had symptoms.

“… although these findings did not capture the impact of the motorcycle rally on residents of other states, they demonstrate the rationale for consistent mitigation measures across states,” the CDC report said.

The study was on Minnesota COVID-19 cases related to the rally but the results are similar to studies of other large gatherings in the U.S. “Other studies have shown that chains of transmission associated with gatherings are not uncommon within the United States (5,6),” the CDC report said.