US flu activity shows signs of declining; COVID indicators mixed

Influenza and SARS-CoV-2 viruses


By several measures—including hospitalization rates—flu activity in the United States declined last week after an unusually early surge to the influenza season, the Centers for Disease Control and Prevention (CDC) said today in its weekly FluView report.

The agency reported 9 flu-related deaths in children, raising the season total to 30.

In its weekly COVID-19 update, the CDC said cases are also down slightly, but wastewater detections of SAR-CoV-2 are up. And a new report highlights flu-COVID coinfections in hospitalized children.

Hospital flu cases, flulike illness drop

Department of Health and Human Services surveillance showed that 23,503 people were hospitalized with lab-confirmed flu last week, down from 25,906 reported the week before, according to the CDC update.

The rate of hospitalizations for flu showed a bigger drop. The weekly hospitalization rate was 4.5 per 100,000 population, down from 5.9 per 100,000 the week before. At least some of this decline, though, could be due to reporting delays, the CDC said.

Flu cases were up a bit in nursing homes. The CDC said 971 (6.8%) of 14,315 long-term care facilities reported at least one influenza-positive test among their residents, up from 5.4% the week before.

The percentage of outpatient visits for influenza-like illness (ILI)—which the CDC defines as a respiratory illness that includes a fever plus a cough or sore throat—declined from 7.2% the week before to 6.9% last week. This is the second such decline in ILI in as many weeks (see the CDC graph below). The rate of ILI visits decreased in all age-groups but the 5- to 24-year-old group, where it inched up.

US flu activity graph

The number of states reporting high or very high ILI activity rose from 46 to 48 last week. But states in the "very high" ranged dropped from 32 to 28.

In US clinical labs, 25.4% of respiratory samples tested were positive for influenza, up from 24.8% the week before. Almost all (99.8%) of flu-positive samples tested in US public health labs last week were influenza A. Of the influenza A viruses, 79.8% were the H3N2 strain and 20.2% were H1N1. All viruses tested have been susceptible to antiviral flu drugs.

The 9 flu deaths occurred from early November to last week and bring the season's total to 30. Eight were associated with influenza A viruses and 1 with an influenza B virus with no lineage determined. Five of the influenza A viruses had subtyping performed, and all were H3N2.

"CDC estimates that, so far this season, there have been at least 15 million illnesses, 150,000 hospitalizations, and 9,300 deaths from flu," the agency said. It recommends that everyone 6 months and older get a flu vaccine.

COVID cases down 3%, deaths drop 13%

In a separate weekly update, the CDC said the 7-day average of confirmed new COVID-19 cases dropped from 67,034 to 65,067 this week, a 2.9% decline. Last week the CDC reported an almost 50% spike in cases.

New COVID hospitalizations were up, from 4,899 daily admission over a 7-day stretch to 5,010, a 2.3% increase. But the 7-day average for daily deaths fell 13.2%, from 445 the week before to 386 last week.

The Johns Hopkins COVID tracker shows 1,087,083 total US COVID-19 deaths and 99,843,680 total cases since the pandemic began.

Detections of SARS-COV-2 in wastewater, however, are rising. The CDC said in its update that about 53% of sites reporting wastewater data are seeing some of their highest levels since Dec 1, 2021. The week before, that level was 38% of sites. About 80% of sites across the country are reporting moderate to high SARS-CoV-2 levels in wastewater.

More than 44% of US counties are experiencing medium to high community levels of COVID-19. Overall, 50 out of 52 jurisdictions had medium or high COVID community levels this week, up from 48 last week.

The CDC also released its latest Omicron variant proportion projections today, which show further increased proportions of the BQ.1 and BQ.1.1 subvariants, which are predominant at 30.7% and 38.4%, respectively. BQ.1 was down a bit, while BQ.1.1 rose slightly. Proportions of other lineages, including XBB, decreased.

The CDC said that, while 68.9% of Americans have received their primary vaccine series, only 14.1% have gotten the updated bivalent (two-strain) booster dose. That percent climbed from 13.5% last week.

Flu-COVID coinfections in kids

In combined flu-COVID news, the CDC and its state partners today published a study in Morbidity and Mortality Weekly Report showing that, during the 2021-22 flu season, 6% of children hospitalized with influenza (32 of 575) had COVID-19 as well.

The public and parents should be aware of the risk for pediatric coinfection and adopt prevention strategies.

The report noted that a higher percentage of patients with coinfection required invasive or noninvasive respiratory support compared with those with flu only.

Among flu-related pediatric deaths, 7 of 44 (16%) involved SARS-CoV-2 coinfection. Only 1 of the 7 deceased coinfected children received flu antivirals, and none had been fully vaccinated against flu.

The study authors conclude, "The public and parents should be aware of the risk for pediatric coinfection and adopt prevention strategies, including considering wearing well-fitted, high-quality masks when respiratory virus circulation is high and annual influenza vaccination and up-to-date COVID-19 vaccination."

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