XBB now makes up 27 percent of COVID in Twin Cities area wastewater

Overall COVID cases and hospitalizations are down

A nurse gives a Pfizer-BioNTech booster shot
While roughly 70 COVID patients per day continue to enter Minnesota’s hospitals, there is still no sign of a post-holiday COVID surge in the state. To the contrary, signs are pointing to a post-holiday dip.
Kerem Yücel | MPR News

While roughly 70 COVID patients per day continue to enter Minnesota’s hospitals, there is still no sign of a post-holiday COVID surge in the state. To the contrary, signs are pointing to a post-holiday dip.

Last week we reported that a new subvariant, XBB.1.5, has spread rapidly in the northeastern U.S. raising nation-wide concerns. This week the Minnesota Department of Health is again reporting that the subvariant’s impact on Minnesota is limited, stating via e-mail that although they have sequenced thousands of COVID-19 cases “we’ve seen 10 cases so far of XBB.1.5." 

This may yet change as the Metropolitan Council is again reporting an increase in the XBB presence in their wastewater monitoring, now making up 27 percent of the viral RNA analyzed at the state’s largest wastewater treatment plant, up from 15 percent last week. Fortunately, they are simultaneously reporting an overall drop in COVID-19 load. 

One other COVID-19 news item concerns some controversy over the effectiveness of the bivalent booster. On Wednesday, the highly respected New England Journal of Medicine published a commentary by Dr. Paul Offit, a member of the Federal Drug Administration’s vaccine advisory board, reviewing two recent articles that suggested minimal differences in efficacy between the original COVID vaccine and the newer bivalent vaccines.  

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Offit’s commentary, which concluded by downplaying the need for those not at risk to get a bivalent booster, has already been covered by Time Magazine among others, leading to some renewed skepticism about the bivalent vaccine.  

It is important to note that other public health experts, including both Dr. Eric Topol, of Scripps Research, and Michael Osterholm, director of the University of Minnesota’s Center for Infectious Disease Research and Policy, have contested this by pointing out that at least six other studies have shown positive results from the bivalent vaccines.  

For example, in a review of the research which he self-published on Wednesday, Topol states, “All of these [studies] converged on the bivalent’s superior neutralizing antibody response to BA.5, as hoped and anticipated, but also against XBB, which is fortuitous since XBB.1.5 is on a rapid path to US dominance now.” 

Seventy-two percent of Minnesotans have now had at least one dose of COVID-19 vaccine, but only 23 percent are up-to-date. Read on for more about where the state currently stands with the on-going pandemic. 

Three things to know from the latest data about COVID-19 in Minnesota: 

  1. Post-holiday dip in cases and hospitalizations, pre-holiday dip in COVID deaths.

  2. COVID-19 viral load entering the Metro Plant down 12 percent from prior week; presence of XBB increases. 

  3. No counties at “high risk” this week, but half of all Minnesotans still live in “medium-risk” counties according to the CDC’s latest COVID community level ratings. 

Post-holiday dip in cases and hospitalizations, pre-holiday dip in COVID deaths 

To avoid any skepticism about the data due to possible holiday reporting interruptions we are again providing recent 3-day, Tuesday-Thursday, averages (both Christmas and New Year’s Day fell on Sundays and many people were off from work on the following Mondays).  

Using the three-day average COVID-19 cases are down, as of Jan. 5, by 27 percent compared with the previous Thursday, and hospitalizations are down by 22 percent. Using a more traditional seven-day average, the dips are not quite as dramatic, but still notable (11 percent and 8 percent, respectively). Either way, these signs are not pointing to a much-feared increase in COVID circulation following holiday gatherings.  

Note that the sub-set of COVID hospital admissions that go to intensive care units is not down but are holding steady at 11 per day.  

Similarly, the lagging COVID-19 mortality data showed a dip to five deaths per day for the week ending Dec. 22 (the 2023 data showing up in red on the graph is preliminary). This is down from the averages of 7.7 and 9.3 per day in the two prior weeks. 

COVID deaths in Minnesota
Minnesota Department of Health data show a slight dip in COVID-19 mortality during the week ending December 22 (most recent finalized data).
David H. Montgomery | MPR News

COVID-19 Vaccination uptake has been slow lately. Last week health department data showed that 18.2 percent of children 6 months to 4 years old had received at least one dose, and this week that increased to only 18.3 percent. The proportion of those age 65 or older who are up-to-date on their vaccinations, including boosters, rose from 59.2 to 59.8 percent. 

COVID vaccination rates in MN by age
According to Minnesota Department of Health data COVID vaccination rates have not risen much for any age group in recent weeks.
David H. Montgomery | MPR News

COVID levels in Metro wastewater decrease from last week, presence of XBB sub-lineages increases 

The most recent wastewater analysis in the state, from the Metropolitan Council and the University of Minnesota’s Genomic Center, shows a 12 percent decrease in viral load entering the Twin Cities Metro Plant for the week ending Jan. 9 as compared to the previous week.  

The Metropolitan Council also notes that the XBB subvariant made up 27 percent of the viral RNA load entering the Metro plant, which almost doubles the level from the prior week. The level of BA.5 and its sub-lineages, including BQ.1, decreased this week and Bonnie Kollodge from the Metropolitan Council summarized that “XBB sub-lineages are replacing BQ.1 sub-lineages in the Metro Plant service area, but the total level of virus decreased, week-over-week.”

COVID load in Twin Cities metro wastewater
COVID load in Metro wastewater declined 12 percent from the prior week.
David Montgomery

The latest data out of the University of Minnesota’s Wastewater SARS-CoV2 Surveillance Study, shows competing signals for the week ending Jan. 1. COVID-19 levels in wastewater increased over the prior month and week in the state’s South West and North East regions. The former region saw both the largest four-week increase of 124 percent and the largest one week increase of 54 percent.  

COVID-19 wastewater levels declined moderately over the prior month and week in the state’s North West, Central and South Central regions. And although the South East region saw a slight 1 percent increase over the prior four weeks, it more recently saw a 21 percent decrease over the prior week.  

The Twin Cities Metro experienced a three percent decline in COVID-19 levels in its wastewater over the prior four weeks, but it experienced a nine percent increase over the prior week. 

Half of all Minnesotans live in counties with “medium” COVID-19 risk 

In good news, there are no counties rated “high risk” according to the Centers for Disease Control and Prevention’s (CDC) “Community Level” ratings this week. Like last week, 30 counties were assigned a “medium” risk rating for the week ending Jan. 11. However, not all the same counties are at medium risk and that makes a difference.  

Last week the combined populations of the 30 counties declared medium-risk comprised 72 percent of the state’s population, while the 30 medium-risk counties this week comprise just over 50 percent. The biggest difference is that Chisago, Dakota, Ramsey and Washington counties in the eastern Twin Cities Metro are rated low risk this week instead of medium risk. Twenty-three percent of the state’s population lives in those four counties. 

Otherwise, there is a lot of overlap between this week’s map and last week’s: central and southeastern Minnesota continue to feature prominently. There are more medium-risk counties in southwestern Minnesota and along the state’s southern border this week and fewer in the northern part of the state.     

While the CDC map has remained relatively stable over the last two weeks, in the sense of the quantity of counties assigned certain ratings, things appear to be moving in a positive direction since 30 percent less of the state’s population is in a medium risk county compared to two weeks ago, when 4 in 5 Minnesotans lived in such a rated county. But that still leaves half of all Minnesotans living at medium risk of community transmission. 

NOTE: For more details and complementary maps showing county-level COVID case and hospitalization rates, click on this sentence to get to the COVID in Minnesota key data page.