Skip to content

COVID-19 update: How long does immunity last?

By LeAnn R. Ralph

MENOMONIE — Now that more than 3,100 people in Dunn County have tested positive for the SARS-CoV2 virus that causes the COVID-19 illness, a good question to ask is — how long does immunity last?

Whether it is immunity from having contracted the virus or immunity from a vaccine, the answer is “we just do not know yet,” said KT Gallagher, director of the Dunn County Health Department and the county’s health officer, during her weekly COVID-19 update via Facebook Live on December 11.

People who have tested positive for the virus are not re-tested for 90 days, which includes people who had a positive PCR test (nasal swab) or a positive antigen test (saliva) with symptoms, she said.

During the 90 days after someone has had a positive PCR or antigen test with symptoms and then have symptoms again, which could be from another respiratory virus, people are asked to stay home, Gallagher said.

After 90 days, if someone exhibits symptoms of the virus, that person is asked to re-test, she said.

Only one person in Dunn County appears to have been re-infected with the virus, but compared to the statewide total of positive cases, Dunn County is a small percentage, Gallagher said.

As of December 11, nearly 430,000 people in Wisconsin have tested positive.

In the southern part of Wisconsin, where there were more infections with the coronavirus early on, the data shows that people who become infected with the virus again often have much more severe symptoms the second time around, Gallagher said.

According to information that is available now, people are believed to have immunity from the coronavirus for 90 days, she said.

As for immunity from a vaccine, there is no information available right now, Gallagher said.

Regarding when a vaccine will be available in Wisconsin, frontline healthcare workers who treat COVID-19 patients will be the first to be vaccinated. The next round of vaccinations will go to people who live and work in long-term care facilities, such as nursing homes and group homes. After that, vaccines will go to first responders, essential workers and public health workers, she said.


One person who submitted a question wanted to know the ages of people who have died in Dunn County from COVID-19.

The average age of death in Dunn County from the coronavirus is 78, while the youngest person who died was 59, and the oldest was “quite old,” Gallagher said.

Statewide, six percent of deaths are in the 50 to 59 year-old age group, and a little more than 50 percent of the deaths are in people who are 80 years of age or older, she said.


Although the Centers for Disease Control and Prevention and the Wisconsin Department of Health Services recently have issued guidelines for an abbreviated quarantine of 10 days if certain parameters are met, “14 days is best,” Gallagher said.

Between 10 and 12 percent of people turn positive after day seven. If someone who has been exposed has a negative antigen test after day six or seven, between 3 percent and 12 percent of those people will turn positive later on, she said.

People who use the abbreviated quarantine of 10 days should not be in a congregant living situation, such as a nursing home, group home or a prison; should continue to wear a mask and do physical distancing; and should be people who can communicate their symptoms, Gallagher said.

People who cannot communicate their symptoms include small children and some people with developmental or cognitive disabilities.

Leave a Comment