US COVID declining after reaching peak

News brief

COVID activity has peaked and is now on a downward trend in many regions of the country, though emergency department (ED) visits and hospitalizations are still elevated, the Centers for Disease Control and Prevention (CDC) said today in its latest update.

SARS-CoV-2 purple blue — NIAID/Flickr cc

The current COVID wave began in June, marked by a slow rise that never approached levels seen last summer.

Wastewater SARS-CoV-2 detections are now at the moderate level and are highest in Northeast, followed by the West and the South.

Nationally, test positivity has declined to 7.8%. ED visits are highest for children ages 4 and younger and are elevated for seniors. Hospitalization rates—elevated for seniors—continue to decline, and less than 1% of deaths in the most recent reporting week were due to COVID.

The CDC’s latest variant projections suggest that proportions of XFG continue to rise, making up 85% of detections.

Flu and RSV activity remain very low

In its other respiratory virus tracking, the CDC said flu and respiratory syncytial virus (RSV) activity remain very low but are showing upward trends. Wastewater detections also remain very low.

In its latest FluView update, the CDC received one more report of a pediatric flu death, which occurred during the week ending December 14, 2024, bringing the season’s total to 281, the highest number in a nonpandemic year since the condition became reportable in 2004.

WHO replaces H1N1 and H3N2 strains for Southern Hemisphere flu vaccines

News brief

Lisa Schnirring

The World Health Organization (WHO) today announced its advisory group’s recommendations for the Southern Hemisphere’s 2026 flu vaccines, which swap out both the H1N1 and H3N2 strains in the current vaccines for the Northern Hemisphere as well as those for the Southern Hemisphere’s last flu season.

vaccine in arm — *SELF Magazine / Flickr cc*

The change in influenza strains affects both the egg- and cell-based vaccines. However, the H3N2 picks are different for the two vaccines. For egg-based vaccines, the experts recommend an A/Singapore/GP20238/2024 (H3N2)–like virus, and for cell-based vaccines, they went with an A/Sydney/1359/2024 (H3N2) –like virus.

Meanwhile, their influenza B Victoria lineage pick is the same one they recommended for the current Northern Hemisphere vaccine and last season’s Southern Hemisphere vaccine. The group did not make a recommendation for the influenza B Yamagata lineage, which has not circulated since March 2020.

No new pandemic-preparedness flu strain picks

The WHO’s flu vaccine composition advisory group meets twice a year, in February to weigh in on Northern Hemisphere recommendations and in September to give advice on Southern Hemisphere vaccines. At both meetings, they also assess the latest zoonotic flu developments and gauge if new candidate pandemic-preparedness flu vaccine strains are needed. They didn’t recommend any new strains at this week’s meeting.

The Food and Drug Administration (FDA) vaccine advisory group is slated to meet on October 9 to discuss strain selection for the 2026 Southern Hemisphere. The Vaccines and Related Biological Products Advisory Committee (VRBPAC) is also slated to make recommendations on the Center for Biologics Evaluation and Research’s allergen-standardization program.