Oregon is currently experiencing a significant spike in seasonal flu cases and hospitalizations this month, potentially leading to the worst flu season in the last decade. This trend aligns with a national pattern, as the Centers for Disease Control and Prevention (CDC) has categorized this flu season as high severity across all age groups for the first time since the 2017-2018 season. This classification indicates that the flu is contributing to an unusually high percentage of doctor visits, hospitalizations, and fatalities this season.
Flu can severely impact even previously healthy individuals. The flu season in Oregon began typically, with transmission peaking around late December. Public health officials monitor flu activity by the rate of positive flu tests ordered by healthcare providers.
During the week of Christmas 2024, 31.5% of flu tests returned positive results, signaling significant community transmission. By mid-January, this positivity rate had dropped to approximately 18%, and hospitalizations were decreasing, suggesting the flu season might be winding down. However, an unexpected rise in the positivity rate and hospitalizations occurred, as reported by Dr. Paul Cieslak, medical director for communicable diseases at the Oregon Health Authority. Last week, 21% of flu tests were positive, with the previous week showing even higher percentages, both peaks attributed to Influenza A.
Due to limitations in tracking flu hospitalizations statewide, health officials use data from the Portland metro area as an indicator of the flu season’s severity. Since the flu season began in October, the Oregon Health Authority (OHA) has documented 1,345 influenza hospitalizations in Clackamas, Multnomah, and Washington counties, a figure comparable to the notably severe 2017-2018 flu season.
To date, OHA has reported 22 hospitalizations among children aged four and under, and 52 among those aged five to 17. In December, two pediatric deaths linked to the flu were recorded. This year, Randall Children’s Hospital has seen an uptick in complex influenza cases among children, including instances where the flu virus has led to secondary bacterial infections or abscesses.
The hospitalization rate is particularly high among individuals aged 65 and older, who represent about half of all flu-related hospitalizations in the Portland area. The CDC recommends annual flu vaccinations for everyone aged six months and older; however, less than half of Oregonians typically receive their flu shot, with this percentage declining over recent years. Five years ago, 36.5% of Oregonians were vaccinated by late February, while only 29% have been vaccinated so far this season.
For those who experience severe symptoms, the flu vaccine may still offer some level of protection against more severe outcomes. A 2019 study funded by the CDC found that even when the flu vaccine did not closely match circulating virus strains, it reduced severe outcomes in children by approximately 75%.
In addition to vaccination, health officials recommend proactive testing for the flu. For the first time this year, an at-home flu test is available over-the-counter at pharmacies, allowing for single-swab testing for both Influenza A and B, as well as COVID-19. Antiviral treatments for the flu are most effective when initiated one to two days after symptom onset.
