What is the high COVID-19 infection rate for unvaccinated Wisconsinites?

With millions of people protected by the coronavirus vaccine, Americans are entering a second pandemic summer, which is considerably more optimistic than 2020.

Memorial Day weekend trips are busy in the United States, with 60% more Americans expected Planning to fly vacation in 2021 From a year ago.Similar highway traffic is expected to increase, with more than 37 million people Plan to drive over 50 miles On the weekend. Some large gatherings have also resumed. The Indianapolis 500 scheduled for May 30th Expected to have more than 135,000 spectators Get off the race.

At the same time, public health officials continue to warn of shrinkage, yet there are a huge number of people who remain unvaccinated.

“If you are not vaccinated, our guidance has not changed. There is a risk of infection,” he said. Centers for Disease Control and Prevention, May 27 meeting A member of the White House’s COVID-19 response team, he encouraged unvaccinated individuals to wear masks and take other precautions on holiday weekends.

Wisconsin public health officials repeated this note.

“The most important thing among unvaccinated people is to avoid meetings and wear masks in public,” said Dr. Ryan Westergard, a state epidemiologist of infectious diseases. , Said when asked about the risks of COVID. 19 spread among unvaccinated people on holiday weekends, May 27 press conference..

A May 21 analysis By Washington post We have shown how the declining case rate in the entire US population masks the prevailing rate of COVID-19 among those who have not yet been vaccinated. This group includes all children under the age of 12 (without qualification) and different proportions of adolescents and adults, which vary by state and county.

on the other hand Breakthrough case —If vaccinated individuals are infected with the coronavirus — if they do occur, they have been observed to be rare and the majority of new infections are among unvaccinated people. It is occurring. As of April 30 CDC identified Of the more than 100 million people vaccinated by that time, a total of 10,262 breakthrough infectious diseases.

In Wisconsin, vaccination rates continue to vary widely among 72 counties, a pattern that has continued over the past year. In Dane County, as of May 28, two-thirds of residents received at least one dose. Door County and Bayfield County also accounted for more than 60%, with 12 more than 50%.

In most counties in Wisconsin, less than half of the inhabitants remain unvaccinated, while in Clark and Taylor counties only one in four inhabitants receive the initial dose. Behind the rest of the state For several months.

Even though millions of Wisconsins are protected by vaccination, COVID-19 continues to circulate and infect those who do not.

Comparing the case rates between unvaccinated populations in the county provides an indication of the level of ongoing risk that unvaccinated people may face in the area. Adjusting the 7-day average for each county of newly identified COVID-19 cases to a per capita rate that includes only the unvaccinated population will help explain this dynamics. This calculation is made by subtracting the number of residents in each county reported to have been vaccinated at least once from the estimated 2019 population. Later, 15% of vaccinated individuals were added, reflecting a careful estimate of breakthrough infections.

In many parts of Wisconsin, the COVID-19 case rate per 100,000 confirmed as of May 27, 2021 doubled when adjusted to reflect only the unvaccinated population. I will. Given that many counties have been vaccinated at around 50%, this difference fits expectations.

In the counties with the highest vaccination rates, the cases in the unvaccinated population are even higher. In Dane County, the average 7-day case rate on May 27 was 3.6 per 100,000. Among the county’s unvaccinated population, the case rate surged to 10.5 per 100,000. On the other hand, the average 7-day case rate of Door County was 0 on May 27 for the first time in almost a year, and the case rate of unvaccinated residents was also 0.

In counties with a low proportion of vaccinated residents, the case rate adjusted for the unvaccinated population does not increase significantly, but it does.

For example, Rusk County had the highest average 7-day case rate in the state on May 27, at 25.4 per 100,000. The rate jumps to 36.3 per 100,000 among the county’s unvaccinated population. Only about 30% of the county’s approximately 14,000 inhabitants had received at least one dose by that date.

In particular, even the highest case rates in Rusk County’s state in late May 2021 are not approaching the seven-day average of the peak seen across Wisconsin in the fall of 2020. In rural areas of northern and western Wisconsin, no one case has yet been seen while densely populated counties have already experienced outbreaks in the area.

Going forward, the geographical pattern of immunization rates is ready to sustain, as immunization rates continue to decline, even though many parts of Wisconsin are far from vaccination targets. The continued risk of COVID-19 infection depends not only on the activity of the disease in the area, but also on the number of vaccinated people and the behavior of those who have not been vaccinated.

“Just being in the neighborhood is not a risk factor for getting COVID,” he said. Ajay Setty, University of Wisconsin-Madison, Public Health and Infectious Disease Epidemiology Researcher. “And it doesn’t necessarily correlate with counties or zip codes. Eventually, you’ll be attending some sort of rally.”