‘Tis the Season for Cheer—and Viruses
As the holiday season approaches, gatherings of friends and family bring warmth and joy—but also the potential for spreading seasonal viruses.
UC San Francisco infectious disease specialist Peter Chin-Hong has highlighted the “Big Four” viruses currently circulating in the United States: norovirus (a stomach bug) and three respiratory illnesses—influenza, COVID-19, and RSV.
A nationwide infectious disease surveillance network, WastewaterScan, led by Alphabet Inc.’s life sciences division Verily, alongside researchers from Stanford and Emory universities, is monitoring these viruses’ prevalence through wastewater testing.
For COVID-19, WastewaterScan data indicates that areas east of Montana, Wyoming, Colorado, and New Mexico are experiencing “high” activity levels. Meanwhile, most Western states remain in the “low” range, with a few hotspots in cities like San Francisco, Seattle, Salt Lake City, and Boise.
However, these patterns are likely to shift as holiday travel accelerates the spread of illnesses—a phenomenon Chin-Hong aptly refers to as “the Great Holiday Equalizer.”
Currently, influenza is garnering significant attention from healthcare professionals and researchers due to its widespread impact.
Flu Season: What Experts Are Watching
Despite the U.S. Centers for Disease Control and Prevention (CDC) projecting a mild flu season, infectious disease expert Peter Chin-Hong has raised concerns based on international trends. He pointed to early warning signs from key regions that often serve as indicators for the U.S., including the United Kingdom and South America.
In early December, the UK reported nearly four times as many flu cases compared to the same period last year. Similarly, South American countries like Chile, Ecuador, and Uruguay saw higher hospitalizations during their winter months than during the 2023 flu season. While other regions of the continent experienced average flu rates, these spikes suggest a challenging flu season could be ahead.
Chin-Hong emphasized the importance of flu vaccinations, noting that the CDC’s forecast assumes some level of “carryover immunity” from last year. However, he cautioned that the full impact of this flu season—and the effectiveness of this year’s vaccines—will only become clear as the season progresses.
Currently, two primary flu strains are circulating: H1N1 and H3N2. The latter, often associated with more severe illness, may explain the increase in overseas hospitalizations. Chin-Hong reassured that this year’s vaccine should provide coverage against H3N2.
“It’s never too late to get vaccinated,” Chin-Hong stressed, adding that the U.S. flu season is just beginning.
He also highlighted concerns about the H5N1 bird flu, which causes a deadly risk. While unlikely, a combination of H5N1 with human seasonal flu could have serious consequences. Vaccination and prevention of seasonal flu remain critical in reducing such risks.
Health Experts Advise Caution Amid Seasonal Virus Concerns
Researchers and health experts emphasize that there is no evidence to suggest H5N1 bird flu can spread from person to person. However, as the virus continues to affect dairy herds and poultry operations nationwide, individuals are urged to avoid raw milk, raw eggs, and undercooked meat as a precaution. Proper cooking and pasteurization effectively neutralize the virus, ensuring food safety.
But it’s not just the flu raising health concerns this season. Other viruses, including norovirus, COVID-19 and RSV, remain prevalent.
Recent data from municipal wastewater shows a rise in COVID-19 levels. However, according to infectious disease specialist Peter Chin-Hong, this increase does not necessarily indicate a corresponding surge in hospitalizations. While COVID-19 cases are ticking upward, the CDC predicts fewer cases in 2024 compared to 2023.
“Some people think the reason we’re seeing fewer cases is that many individuals, particularly in California, were recently infected, and that carryover immunity is offering some protection,” Chin-Hong explained. “Another hypothesis is that the virus has circulated enough in the population, so it might just be lower this year.”
COVID-19 and Other Respiratory Illnesses: Expert Recommendations for Prevention
Peter Chin-Hong noted that COVID-19 remains a concern due to its adaptability and ability to produce recombinant variants. “Coupled with low vaccination rates, the fear with COVID is always that it could surge back,” he warned.
To protect against influenza, COVID-19, and RSV, Chin-Hong recommends the “three V’s”: Vaccinate, Ventilate, and Wash your hands frequently. He also highlighted the importance of mask-wearing in indoor settings or when in close contact with others. When possible, socializing outdoors or in well-ventilated areas is the safest choice.
For norovirus, which typically causes gastrointestinal distress and spreads through contact with contaminated surfaces (such as buffet serving spoons, handrails, or airline trays), the key preventive measure is frequent handwashing. Avoiding touching your face is also essential, as hands are the primary source of transmission.
Chin-Hong shared that the norovirus seems to be circulating widely, saying, “Anecdotally, many of my colleagues have been out with it.”
Additionally, he mentioned that pertussis (whooping cough), walking pneumonia, and rhinovirus (the common cold) are also on the rise.
Finally, Chin-Hong stressed the importance of staying home when feeling unwell. “Nothing stops a virus or bacteria from spreading like isolation,” he said, even if it means missing out on holiday celebrations.
Reference: Yahoo
