Novel coronavirus SARS CoV2, which causes COVID-19. Meanwhile, new COVID mutations called variants are now spreading across the U.S., including the Delta variant. Microphotography by National Institute on Allergy and Infectious Diseases.
In the last week, one in four people in Wisconsin who have gone for a COVID-19 test have been found to be infected with the novel coronavirus.
As of Sunday, according to the state Department of Health Services (DHS), on average, 24.5% of tests given for COVID-19 over the last seven days were positive.
That’s the highest positivity rate that has been recorded in the state since the start of the COVID-19 pandemic. A very high rate can suggest that not enough people are getting tested for the virus, according to public health experts.
But the high rate also suggests just how widespread and contagious the novel coronavirus has become in Wisconsin.
“This current increase is being fueled by the new omicron variant, which is more infectious than delta” — until recently, the predominant variant of the virus in Wisconsin, said Ajay Sethi, an epidemiologist and faculty director of the master’s degree in public health program at the University of Wisconsin School of Medicine and Public Health.
Several school districts changed their post-holiday-break plans in response to the latest wave of infections. Milwaukee Public Schools said it would operate virtually until next week and the Madison school district said it would do so at least until Thursday.
Across the state, hospitals continue to be operating at near-capacity. According to the Wisconsin Hospital Association (WHA), more than 95% of intensive care unit beds in the state are in use, about one-third of them occupied by COVID patients while the remainder are hospitalized for other conditions.
With the high occupancy, “don’t get in a car accident or have a heart attack or a burst appendix,” said Geoffrey Swain of the Wisconsin Public Health Association. “Beds are really close to capacity. Hospitals are short-staffed, and they are burned out.”
In the Fox Valley, according to the WHA, there is no available capacity in ICUs, intermediate care or medical-surgical care.
The DHS record of the number of Wisconsin residents who have been infected at least once with the virus has now topped 1 million since the start of the pandemic almost two years ago.
The omicron variant is more likely than previous forms of the virus to cause breakthrough infections in people who have been vaccinated. “That’s also fueling the surge,” Sethi said. In addition, “children are less likely to be vaccinated than adults in general, and we’re seeing rises in COVID cases in kids more than in some of the older adults.”
Sethi said both the rise in in infections in children as well as the increased breakthrough infections help explain why Dane County, where the vaccination rate for COVID-19 is highest in the state, has joined other parts of the state in having “critically high” spread of the virus, according to weekly county-by-county data that DHS posted Dec. 29.
Despite the greater risk of breakthrough infections from omicron, the COVID-19 vaccines continue to show their effectiveness in preventing more serious disease, hospitalization and deaths, both Sethi and Swain said.
While the omicron variant is spreading far more quickly and easily than previous forms of the virus, there have been tentative suggestions that it might cause less severe illness.
Biologically, it appears that omicron may be more likely to replicate in the nose and other parts of the upper respiratory system, said Sethi, resulting in milder symptoms. Previous versions were more likely to replicate further down, into the lungs, producing more serious symptoms.
But other factors complicate that assessment. Because more people who are vaccinated are getting infected by the variant, the vaccine may be helping them avoid a more severe illness. And because younger people are increasingly getting the infection — and are believed to be less likely to experience severe symptoms — that might skew the evidence, leading omicron to appear milder than it would be in older or unvaccinated people, Sethi said.
Additionally, said Swain, there is still “a lot of delta, and delta is very virulent” — causing much more serious illness. He is concerned that if people take fewer precautions because they assume omicron is milder, that would allow the delta variant to spread, too, with more serious effects.
In addition, as omicron spreads so much more quickly, it could still drive up hospitalizations overall even if an individual patient has a lower chance of having to go to the hospital, Swain said.
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