REGIONAL- Ever since the growth of at-home testing for COVID-19, Minnesota health officials have known that official case counts, which are based on clinical testing only, significantly underestimate the actual prevalence of the disease. As a result, they’ve turned to hospitalizations and deaths as a more accurate measure of the pandemic’s severity, and now report case counts weekly rather than daily.
But now there’s evidence that the incidence rate of COVID cases in the community could be even higher than health officials might have projected, as new research indicates the possibility that more than half of the people infected with the Omicron COVID variant aren’t aware they have it or have had it.
Those were the findings of a collaborative group of researchers from the University of California-Los Angeles, Cedars-Sinai Smidt Heart Institute, and Abbott Laboratories, who drew blood samples and measured COVID antibody levels from 210 patients and employees to come up with their results.
The report, published Aug. 17 in the Journal of the American Medical Association Network Open, documents that 56 percent of those who tested positive for COVID-19 didn’t know that they had been infected because they either had no symptoms at all or mild symptoms they attributed to a cold or allergies.
Almost since the start of the pandemic, researchers have demonstrated that some cases of COVID are asymptomatic, that a person can be infected with the virus and spread it to others without having any COVID symptoms, and this research is additional confirmation of that phenomenon.
But it also shows that Omicron’s generally milder symptoms overall may be contributing to the more aggressive spread of the variant since those infected are less likely to recognize it as COVID. That presents additional risk for those over 50 and those with underlying health conditions who are susceptible to more severe illness in the event they become infected.
It also may explain in part why the case numbers around the country are still running well above those reported the prior two summers, even though the current case counts are known to be significant undercounts.
“There’s just a tremendous amount of transmission,” said University of Minnesota infectious disease expert Michael Osterholm in a recent podcast. “Hospitalizations have dropped slightly over the past two weeks; deaths have remained pretty steady over the past few weeks with an average of just under 500 lives lost each day in the U.S.”
Osterholm emphasized the ongoing seriousness of the death toll.
“That equates to about 182,000 deaths per year in this country,” he said. “It now makes (COVID) the fourth leading cause of death in this country.”
Back to school
Minnesota children are heading back to school next week, and the Mayo Clinic’s hotspot map predicts that St. Louis County’s COVID plateau will continue at least through next Saturday.
Only four in ten of Minnesota’s elementary-age children have completed an initial vaccine series, and only one in ten is fully up to date with their vaccinations. The numbers get higher as the grade levels go up, but even among 16-17-year-olds only three in ten have their vaccinations up to date.
The COVID landscape for schools today is vastly different from the mandates of masking and possibilities of schoolwide distance learning of two years ago. Changing recommendations from the Centers for Disease Control and the Minnesota Health and Education Departments have administrators trying to piece together COVID response plans on a district-by-district basis while relying on uncertain data to try to anticipate what might lie ahead.
Ray Jobe, the St. Louis County health department specialist working with schools around COVID this year, talked about one of the recent CDC changes, that of eliminating the requirement for those exposed to a case of COVID to quarantine.
“Parents and students were all sick of the mandates,” he said. “Isolation is still there for anybody who tests positive, but they’re not requiring quarantine for anybody that’s been exposed or suspected of being exposed. They do still recommend that anybody that’s been exposed or suspected to have been exposed should still be wearing a mask for ten days. I think that’s going to vary a lot by each district.”
“It’s going to be dependent on school districts to set their plans in place,” he continued. “I think it’s going to be tricky. One of the important things is that they’re going to base their plans primarily off of the CDC community level of transmission. But they also should be considering the rates of student and staff absenteeism as well in trying to determine what strategies they should be implementing.”
Jobe said that the changes in the COVID surveillance system over time have complicated things for local districts.
“The further we’ve gotten into this pandemic the worse our surveillance system has gotten, especially with home tests. Home tests are helpful because it provides better access for almost everyone, but it makes it really difficult to get an accurate picture of your case rates, especially the smaller areas get,” he said.
Schools and daycares are still being asked to report identified cases on a weekly basis to the health department, and that requirement is helping to give health officials more insight into what may be happening in the surrounding community.
“Schools will still have their hyper-localized data and they’re really going to have to lean on that for when they implement their mitigation strategies,” Jobe said.
County health department director Amy Westbrook said that the problem for schools might not be with student infections.
“It may be that the biggest challenge for schools this fall is maintaining operations,” she said. “What we saw last spring after most of the schools dropped their mask mandates was staff and teachers getting sick and staying out of classrooms. That really made it challenging from a continuity of operations perspective. A teacher can teach with fewer kids, it doesn’t matter. But if the teacher is not there, they can’t learn.”
Omicron boosters
The U.S. Food and Drug Administration was expected to give the green light this week to two new COVID booster shots tailored to better protect against the BA.5 and BA.4 Omicron variants, with about 175 million shots purchased by the federal government becoming available once the Centers for Disease Control issues the accompanying guidance for administration.
Almost 90 percent of reported cases are now caused by the BA.5 variant, with the remainder attributed to BA.4 and a subvariant of that. But while the original Omicron variant rapidly spawned more and more infectious subvariants that replaced prior ones, BA.5 has been the dominant variant in the U.S. since early July with no apparent successor on the horizon at this time.
Both Pfizer and Moderna have boosters awaiting emergency use authorization, but their ultimate impact on the course of the pandemic is uncertain. Neither booster has been tested in humans yet. Both companies have submitted animal testing data for consideration that has not been publicly released. Emergency use authorization can be granted by the FDA using that data, but full approval will require human testing, which is scheduled to begin in September.
Last week a team of Australian medical researchers posted an analysis of prior research on COVID-19 boosters to the medRxiv website aimed at predicting the effectiveness of variant-tailored boosters. Overall, the group found that targeted boosters added to the effectiveness of traditional boosters by up to 13 percent.
The country’s experience with booster uptake to date hasn’t been promising in that regard, and Minnesota’s data reflects that of the nation.
Since additional boosters were authorized by the CDC in March for those 50 and older and in May for everyone five years of age and older, just over 500,000 Minnesotans have taken advantage of them to bring their vaccination status up to date, according to data on the state’s vaccine dashboard. The current percentage of Minnesotans who are up to date with the recommended boosters is only 32.2 percent, and that number has risen only about 10 percent since booster eligibility was expanded.
Osterholm has repeatedly noted that the major challenge faced in Minnesota, the U.S., and around the world is taking a vaccine and turning it into actual vaccinations, a problem borne out by the low booster uptake data.
“I’m not convinced that this will be the silver bullet that many are hoping for,” he said. “There are a few reasons for this, but it can all be summed up in a statement that you’ve all heard me say dozens of times by now. We cannot boost our way out of this pandemic. Part of the reason for this is that by making the variant specific vaccines, we will always be a few steps behind this virus.”
“Our booster uptake is already alarmingly low,” Osterholm continued. “I don’t expect this to change with a new Omicron specific booster, regardless of how effective that booster is. This vaccine may add some protection at an individual level, but I think it’s unlikely it’ll have a large impact on our population as a whole.”