Flu season begins with rising cases in the US
The latest data on respiratory illness in the United States indicates that various factors, including social gatherings, are contributing to increased transmission of influenza. A new virus variant known as subclade K is driving an early and busy flu season, which has also been observed in parts of Asia, Australia, and Europe, reports BritPanorama.
For the week ending December 6, the proportion of doctor’s visits for symptoms consistent with influenza rose to 3.2%, according to the US Centers for Disease Control and Prevention (CDC). This marks an increase above the national baseline known as the epidemic threshold, signaling the official start of flu season, noted Dr. Caitlin Rivers from Johns Hopkins Bloomberg School of Public Health.
Two key indicators are used to determine the start of the flu season: the calendar date, which is week 40 (the first week of October), and flu activity levels. Dr. Rivers explains that the 3.1% threshold indicates the onset of flu season, and current trends suggest heightened activity.
Currently, at least 14 public health jurisdictions are reporting moderate to high flu activity, particularly concentrated in the Northeast. This includes New York City, where flu activity is classified as very high, alongside other areas in New York and New Jersey experiencing high levels. Louisiana and Colorado are also noted for their elevated flu activity, along with several others including Texas and Puerto Rico. Recently, the first reported flu-related death of a child occurred in the United States this week.
In light of rising influenza cases, Dr. Tim Uyeki, chief medical officer of the CDC’s influenza division, emphasized the urgency of vaccination, stating, “We know that from our surveillance, influenza activity is increasing in the US right now, and therefore that the time to get vaccinated for this season is right now.”
Early signs of a rough flu season
Indicators point to a potentially severe flu season ahead. In New York State, flu cases have surged about two weeks earlier than usual, according to Dr. James McDonald, commissioner of the New York State Department of Health. Recent data shows that flu hospitalizations have doubled weekly, prompting urgent alerts to hospitals about the rapid rise in cases.
Highlighting the unusual trajectory, Dr. McDonald mentioned that the graph of flu cases resembles a J-shape, which signifies a rapid increase in severe cases compared to previous years. He stated, “It’s here, and it announced itself quite loudly.” The rapid rise in hospitalizations is unprecedented, reflecting a larger number of flu diagnoses than in the previous year.
Most flu viruses currently analyzed have been identified as subclade K, a variant of the H3N2 strain, which is part of the influenza A category. The New York health alert warns that flu seasons predominantly featuring this strain are typically associated with more severe symptoms, particularly among older adults, leading to increased healthcare demands.
Other nations such as Japan, China, the UK, and Canada are also experiencing busy flu seasons. In Australia, where subclade K was first detected, nearly half a million confirmed flu cases have been logged, surpassing the previous year’s record.
Despite these alarming trends, experts remain cautious. Dr. Jennifer Nuzzo from Brown University stated that an especially bad flu season last year doesn’t guarantee a repeat, as historical patterns may not hold with the emergence of new variants.
Vaccines vs. a new flu variant
The current flu vaccines do not specifically target the new subclade K variant, as it was identified after the vaccine strains were selected. Nevertheless, existing vaccines appear to provide reasonable protection against this variant, particularly in children, where they have been shown to significantly reduce the risk of hospital visits.
A recent study by the UK’s Health Security Agency indicated that the flu vaccine cut the odds of emergency department visits by nearly 75% for children. Meanwhile, the efficacy for adults ranges from 30% to 40%, highlighting disparities in protection across demographics.
Experts caution that while promising, the results seen in the UK may not directly translate to the US due to differences in vaccine production methods. Dr. Rivers noted concerns about the potential for diminished effectiveness of the US vaccines compared to UK counterparts, which predominantly use cell-based production methods.
With flu season rapidly progressing, health officials emphasize the importance of timely vaccination and continued vigilance, as any level of protection remains preferable over none. Current CDC data shows a concerning decline in vaccination rates among children, potentially jeopardizing their health as the flu season intensifies.
How to stay safe from flu
Vaccination can significantly lessen the severity of flu symptoms and reduce hospital visits, but is not foolproof in preventing infection. Therefore, adopting multiple preventive measures is advisable. Experts recommend wearing masks in crowded places, ensuring good ventilation indoors, and considering environmental interventions like air purifiers.
Flu symptoms can manifest abruptly, including high fever, cough, and body aches. Early testing can be pivotal, as antiviral medications are most effective within the first two days of onset. Annual insights from public health advocates urge adherence to preventative strategies as the ongoing flu season unfolds.
