Though US flu activity continues to increase slightly in children, overall levels remain low nationally, as do COVID markers, the Centers for Disease Control and Prevention (CDC) said today in its respiratory disease updates.

Percent positivity for flu has trended upward over the past few weeks but is still low, at 1.6% at clinical labs, where nearly 93% of detections are influenza A. Meanwhile, emergency department visits for flu increased slightly among children and adolescents. 

No new pediatric flu deaths were reported, keeping the season's total at one. One death was reported for the 2023-24 season, which occurred in a child who died in May, bringing the number for last season to 205. 

COVID activity continues to decline in most areas, the CDC said in its weekly respiratory virus snapshot. 

"Across the nation, COVID-19 infections are predicted to decline in some states, and grow slowly from a low level in others," the agency said. Wastewater detections are still at the low level and are highest in the Midwest. WastewaterSCAN, a national wastewater monitoring system based at Stanford University in partnership with Emory University, said yesterday that SARS-CoV-2 detections remain low, with no significant trend up or down over the past 3 weeks.

RSV picks up more steam; more Mycoplasma and pertussis

In other respiratory illness tracking, the CDC said respiratory syncytial virus (RSV) activity is elevated and continues to increase in the East and South and is trending upward in the Central region, especially in young children. Also, infections caused by Mycoplasma pneumoniae ("walking pneumonia") continue to rise in the younger age-groups.

For pertussis (whooping cough), the CDC recently reported that illness patterns have returned to pre–COVID-19-pandemic levels. For the week ending November 9, preliminary data show that more than five times as many cases have been reported this year than last year. 

New data from the UK Health Security Agency (HSA) show that the number of serious antibiotic-resistant infections last year in England surpassed pre–COVID-19-pandemic levels.

The English Surveillance of Antibiotic Prescribing and Utilisation Report (ESPAUR) shows there were an estimated 66,730 serious antibiotic-resistant infections in England in 2023, compared with 62,314 in 2019. The increase was largely due to an uptick in antibiotic-resistant Escherichia coli, which was responsible for an estimated 68% of drug-resistant bacteremia cases. 

Resistance to multiple classes of antibiotics in cases of E coli bacteremia also increased compared with 2019, and resistance to most classes of antibiotics increased in Klebsiella pneumoniae as well. The rates of reported carbapenemase-producing organisms from all sample types more than doubled from 2021 (4.7 per 100,000) to 2023 (10.1 per 100,000).

Widening disparities

The ESPAUR data also reveal that people living in the most economically and socially deprived areas of England were 42.6% more likely to have an antibiotic-resistant infections than those living in the least deprived areas. That's up from 29.6% in 2019. Ethnic disparities were found as well, with the highest proportion of resistant infections reported in Asian or Asian-British ethnic groups (39.4%).

"Increasingly the first antibiotics that patients receive aren't effective at tackling their infections," HSA Chief Executive Professor Dame Jenny Harries said in a press release. "That's not just an inconvenience—it means they are at greater risk of developing a severe infection and sepsis. Our declining ability to treat and prevent infections is having an increasing impact, particularly on our poorest communities."

Antibiotic use in England also rose in 2023, increasing by 2.4% compared with 2022 and returning to 2019 levels after dropping during the COVID-19 pandemic. The UK AMR National Action Plan has set a target of reducing total antibiotic in people by 5% from the 2019 baseline.

Our declining ability to treat and prevent infections is having an increasing impact, particularly on our poorest communities.

The preventive monoclonal antibody nirsevimab (Beyfortus) was 89% effective against infant hospitalization in Alaska for respiratory syncytial virus (RSV) in their first RSV season and 76% and 88% effective against medically attended illness for those in their first and second seasons, respectively, estimates a study published yesterday in Morbidity and Mortality Weekly Report.

Researchers from the US Centers for Disease Control and Prevention (CDC) and their partners in Alaska analyzed rates of hospitalization and the receipt of outpatient or hospital care among 472 infants younger than 20 months treated for respiratory virus infection in Alaska's Yukon-Kuskokwim Delta region, located on the state's west coast, in the 2023-24 respiratory virus season.

"Historically, American Indian and Alaska Native (AI/AN) children have experienced high rates of RSV-associated hospitalization, with threefold to sevenfold higher rates in Alaska's Yukon-Kuskokwim Delta region than in other U.S. areas," the study authors wrote.

88% effective against need for treatment in second season

Of the 472 children with medically attended visits (14% hospitalization, 70% emergency department, and 16% outpatient clinic), 14% tested positive for RSV, and 86% tested negative. The median time from nirsevimab receipt to a medical visit was 91 days. In total, 48% overall had received nirsevimab at least 7 days before their medical visit (median, 91 days). 

Historically, American Indian and Alaska Native (AI/AN) children have experienced high rates of RSV-associated hospitalization, with threefold to sevenfold higher rates in Alaska's Yukon-Kuskokwim Delta region than in other U.S. areas.

Among the 292 children in their first RSV season, nirsevimab was 76% effective (95% confidence interval [CI], 42% to 90%) against medically attended RSV and 89% effective (95% CI, 32% to 98%) against hospitalization. 

Estimated nirsevimab effectiveness against RSV requiring medical care among the 180 children in their second RSV season was 88% (95% CI, 48% to 97%). Effectiveness was 90% at 7 days to 3 months and 77% 3 to 6 months post-receipt, but the authors noted wide and overlapping confidence intervals.

"These findings support current CDC recommendations for all infants in their first RSV season to either receive nirsevimab or be protected through maternal vaccination and for children entering their second season with increased risk for severe RSV illness, including all AI/AN children, to receive nirsevimab," the researchers concluded.