Masks (Chris Zúniga | via Flickr CC BY-NC 2.0)
Some time in mid-January, some people in Wisconsin who were wearing face masks stopped doing so — and every day, a few more people gave them up. In early February, people started traveling more, and longer distances.
By a week before St. Patrick’s Day, the state’s steady decline in the number of new COVID-19 cases each day skidded to a halt. And now, even as Wisconsin continues to set records for getting people vaccinated for the coronavirus, the number of new infections every day is going up as well.
The growing number of vaccinated state residents holds promise that the state will successfully tamp down the virus some time in the coming months. But the increase in new cases is making that task more difficult — and means it will take longer.
Mutant forms of the coronavirus are helping to drive the increased spread in general, according to public health officials. On Monday, Public Health Madison & Dane County (PHMDC) reported an outbreak at a child care center where 21 children and employees tested positive for the coronavirus variant known as B.1.1.7. Another 14 family members of those individuals have also tested positive.
“Several dozen more close contacts were identified from the 35 people who tested positive,” according to a statement from PHMDC.
Sarah Mattes, communications manager for the agency, says that while the outbreak “is concerning to us” and “a reminder to everyone that we aren’t through this yet,” the agency remains on track to continue a phased reopening that it announced on Friday, April 2.
The B.1.1.7 mutation is among those that have been identified as more easily transmitted among younger people. But the Dane County child care outbreak does not necessarily illustrate that. “We know it is more transmissible,” Mattes says of the variant, “but cases seem to be rising pretty consistently across multiple age groups, not just children.”
Wisconsin public health practitioners aren’t yet ready to call the case increase in Wisconsin a surge. But if it turns out to be one, the last couple of weeks will mark its beginning.
“You really do need to have a larger rise to call it a surge, but we shouldn’t close our eyes to what’s happening,” says Ajay Sethi, an epidemiologist and faculty director of the public health program at the UW-Madison School of Medicine and Public Health. In other states, he points out, there has been “a very similar creep upward” before a new spike in cases. “So we should treat it as a surge if possible, because the prevention is much better than a reaction after it happens.”
The variants are one likely reason for the recent increase. The mutant versions of the virus spread more easily. In addition, younger people appear to be more susceptible to them than to the predominant version of the virus earlier in the pandemic, says Geof Swain, president-elect of the Wisconsin Public Health Association.
Swain and Sethi also blame “pandemic fatigue” for the current uptick in cases. “People are exhausted,” says Swain. “It’s totally understandable.”
And some people are likely feeling complacent — an unintended consequence of the state’s vaccination success. A person with just one shot of a two-shot series might still “feel like, ‘Most likely I have immunity,’” says Swain, and decide to relax behavioral measures such as wearing a mask or avoiding gatherings.
That sense of optimism may extend to some unvaccinated people as well, he adds.
“I spoke with someone who has this opinion, just this morning — [that] there’s a lot of people that have been vaccinated and a lot of people that have been sick, so we’re basically to the point of herd immunity,” says Swain. “We’re not actually there at all.”
Herd immunity results when the number of people in the population who have been made immune, either because of a vaccine or because they’ve survived an infection, is high enough that the virus doesn’t have easily available new, susceptible people to spread to where it can replicate and spread further.
The state Department of Health Services (DHS) has set a goal to get 80% of Wisconsin’s population vaccinated to reach herd immunity. The state is roughly one-fourth of the way toward that goal: About 20% of Wisconsin residents are completely vaccinated; another 13% have received at least one dose of one of the two-shot vaccines. (Public health providers aren’t counting on the 10% of the state’s population who have survived a COVID-19 infection to be immune without a vaccine.)
Swain explains the power of herd immunity with a bowling analogy. When a bowler sends the ball down the alley to a full array of pins and the ball hits one pin, there are enough in close proximity that get knocked down along with the first. That’s the situation when fewer people are vaccinated.
But when only two or three pins remain and they are far apart from one another, the ball won’t hit as many at once, and when there’s just one pin, “it’s hard to hit,” Swain says. “That’s what the virus faces when it comes into a population when 85-90% of people are immune.”
The number of new cases — and the percentage of positive tests for infection with the virus — began falling steadily in the first week of January, according to DHS. The department reported that on Jan. 5, 11% of the tests given each day over the previous seven days were positive for the virus. Positive tests and the average positive test rate declined through March 10, when, on average, 2% of tests for the previous seven days were positive.
Since then, they’ve started to climb back. As of Sunday, an average of 3.4% of tests over the previous seven days were positive, according to DHS.
The shift in numbers follows two other shifts in personal behavior.
Both the Institute for Health Metrics and Evaluation (IHME) at the University of Washington and the GeoDS Lab at the UW-Madison Geography Department have been publishing data on how much people are traveling using information from tracking mobile phones. Both show that in Wisconsin, people went from traveling much less frequently and shorter distances in early February to much more frequently and longer distances by mid-March.
Movement is back up to the level it was before the state’s shelter-in-place order, known as Safer at Home, was issued in March 2020. “Part of it is because it’s April, and some of it also is that desire to be normal again,” says Sethi. Some of the movement involves people who are vaccinated, which federal health guidelines have said is safe, he adds, “but my guess is that there are a lot of other people who are also taking fewer precautions.”
The University of Washington also reports data, based on a series of surveys, for each state on how much people are complying with mask requirements or recommendations. In Wisconsin, mask use peaked at about 75% of the population in mid-January; over the next two and a half months it drifted down to 68%. (The data was last updated before the state Supreme Court’s ruling on Wednesday, March 31, throwing out the state’s continued health emergency for the pandemic and the mask order that went with it.)
Swain says reversing those trends — and pulling the rate of infections back down again — would mean fewer people get sick. Reducing the spread of the virus also reduces the chances for more mutations, some of which might be more resistant to vaccines.
“But the numbers are still high right now,” Swain adds. “We’re like, doubling our risk, not only because there’s a lot of different viruses out there, whatever they might be, but because we’re basically inviting the virus to make more mutations.”
Sethi says Wisconsin and the nation overall have followed a pattern of surges in infections followed by an upswing in adherence to precautions in response to public health messaging, which then leads to a decline in new cases.
“Every time we’ve had a decrease, it was around when messaging really ramped up,” Sethi says. In the midst of the state’s last big surge in November, hospitals opened up their doors to the media. “Hospitals brought the cameras in, and everybody saw what was going on in there,” Sethi says. “At some point, people react. And then when it goes down, people react and take fewer precautions.”
The messaging now needs to emphasize the risk of a surge — and the importance of preventing it, he says. “Messaging can work. And that’s really important.”
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