As weekly COVID cases drop, health officials say ‘hidden wave’ is not a major concern for now

By Jon King, Michigan Advance

While COVID-19 cases and hospitalizations in Michigan have declined after several weeks of increases, there have been concerns raised that the true rates of infection might be higher because of a decrease in reporting.

However, state and local health officials say while increased home testing may lessen the numbers of people officially reporting positive COVID results, it doesn’t necessarily mean that the rates of infection are substantially higher than what is known, even as the BA.2 omicron subvariant circulates.

According to numbers released Wednesday by the Michigan Department of Health and Human Services (DHSS), the state added 19,535 cases and 50 deaths from COVID over the previous seven days, the second straight week of declines following six weeks of increases. It’s also well below the 2022 peak in early January when there were approximately 20,000 cases per day.

The positivity rate also declined, down to 14.7% from 15.2% a week ago, although health officials say the goal has been to keep that rate at 3% or less.

Since the start of the pandemic, Michigan has reported 2,547,366 cases of the disease, resulting in 36,407 deaths. Johns Hopkins University reports that there are about 530 million confirmed cases worldwide and 6.3 million deaths, including 84 million confirmed cases and 1,007,319 deaths in the U.S.

DHHS spokesperson Chelsea Wuth tells the Michigan Advance that trend tracks with the infection models they have been closely monitoring, which indicated COVID cases in Michigan would plateau toward the end of May. 

“There are some early signs that the uptick in cases is slowing, and we will be watching the data closely to see if we are reaching a plateau,” said Wuth. “We will continue to monitor cases, hospitalizations and deaths and keep the public updated if the situation changes. MDHHS encourages Michigan residents to pay attention to local guidance as some communities may be at a higher risk of COVID-19 transmission and Michiganders should consider this information as they go about their daily lives and make personal decisions on masking and other strategies to protect themselves from the virus.”

Health officials are warning that two new omicron subvariants, BA.4 and BA.5, are poised to become dominant across the country.

Despite the back-to-back weekly declines, 14 counties remain at a “high” community level, per the Centers for Disease Control and Prevention (CDC): Alger, Calhoun, Kalkaska, Livingston, Mackinac, Macomb, Manistee, Marquette, Monroe, Oakland, Schoolcraft, Washtenaw and Wayne. 

Michigan currently has an overall vaccination rate (one or more doses) of 67.2%, putting it in the bottom third of state vaccination rates. About 60.4% of the state’s population has been fully vaccinated.About 78% of the entire United States population has received at least one dose of a COVID-19 vaccine.

Meanwhile, the rate of those seeking testing to confirm COVID infections also fell from 163,734 to 124,358, a 24% decline. That particular statistic has helped fuel concerns over a potential “hidden wave” of COVID infections due to a decline in reporting. This is partly due to the proliferation of at-home tests, as well as changes in how data is collected and disseminated to the public.

For example, DHHS now only posts case and testing data once per week, as opposed to three times a week previously.

However, Ingham County Health Department Health Officer Linda Vail told the Advance COVID reporting has never been the sole factor in determining the level of infection.

“There’s always been plenty of asymptomatic people who never got tested,” said Vail, “or plenty of people who don’t like the system that don’t get tested, those sorts of things. So it’s really not a concern, because enough people do get tested that what that does is provide us a random sampling.”

Vail says that regardless of whether every single case is getting tested, the pattern that they see is what is relevant from a statistical perspective, and will demonstrate if the infection curve is going up or down.

“In other diseases, such as the flu, we do it via a sentinel surveillance system that by no means intends to test every case,” she said. “And yet we still use that information to tell us when things are on the rise, when they peak out, when they’re going back down. So this really doesn’t vary much from that.”

Vail says using a similar surveillance system for COVID makes it highly unlikely that there would be an undetected surge, because even if the overall level of testing is down, the trend would still be apparent statistically speaking.

If they’re testing at home, that usually means they’re also doing the things that they need to do after they get a positive test. Otherwise, they wouldn’t do it. They wouldn’t bother.

Ingham County Health Department Health Officer Linda Vail

“I’m not concerned that there is some hidden surge that we don’t know about, because I know how our flu surveillance system works,” said Vail. “And I know even absent testing every single case we know what’s going on. We know when that surge is, we know when that peak is, we know when those numbers are going down and that is based on a very random sampling of people who have flu. It is not based on testing. That’s not a practical way.”

As for the increase in home testing contributing to a lower number of officially reported COVID infections, Vail looks at it with a glass half-full point of view.

“Hey, at least they’re testing,” said Vail. “If they’re testing at home, that usually means they’re also doing the things that they need to do after they get a positive test. Otherwise, they wouldn’t do it. They wouldn’t bother. Typically, when somebody does a home COVID test, they then follow the guidelines of staying at home for five days and notifying people that they may have been in close contact with, so there’s nothing wrong with home testing.”

“People not getting tested does not put us on our back foot, not ready for what’s going to happen next. There is enough testing. I mean, you just think about the whole concept of random sampling. You know, if you, if you random sample enough for a specific thing, then, then you basically get a reliable piece of information,” she added. “Whether it’s every single, you know, of the things that you want to count or not, it doesn’t really matter. As long as it’s a big enough random sampling to give you reliable statistical information.”


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