Early flu season hospitalizations hit a 16-year high

Early flu season hospitalizations are already running ahead of schedule in the United States, and the timing is the story as much as the totals. Flu activity is still low nationally, according to the Centers for Disease Control and Prevention, yet the season has arrived before many households have booked a flu shot. That gap between a quiet national picture and a fast local climb is what health officials are watching, because an early start can put pressure on clinics and hospitals weeks before the usual winter peak. The number of metro areas at moderate activity rose sharply in a single week, an early sign that local hot spots are forming even while most of the country stays quiet.

The clearest signal on early flu season hospitalizations comes from FluSurv-NET, the CDC network that tracks lab-confirmed flu hospitalizations in selected counties across fourteen states, covering roughly a tenth of the population. It counted 798 lab-confirmed flu hospitalizations between October 4 and October 17. The observed weekly rate for week 41 was 1.1 per 100,000 people, unchanged from the week before, while the CDC estimated that the true rate after accounting for reporting delays likely fell between 1.5 and 2.0. That estimated range is the highest for that point in the season since the 2010-11 season, the agency said in its FluView report for that week.

What the laboratory data show

Laboratory data point in the same direction for early flu season hospitalizations. Clinical laboratories reported 5.7 percent of respiratory specimens positive for flu, up from 5.0 percent the week before. Outpatient visits for flu-like illness stood at 2.2 percent, below the national baseline of 2.9 percent, which shows how much of the early rise is still concentrated rather than spread evenly. Hospitals reporting to a separate CDC system logged admissions described as stable but trending upward, and no pediatric flu deaths had been reported for the season when the report was released. Emergency visits with a flu diagnosis also rose among children and teenagers while holding steady among adults, according to the same CDC summary.

One strain is doing most of the damage so far in these early flu season hospitalizations. Of 241 influenza A specimens subtyped by public health laboratories in that week, 99.2 percent were H1N1, and none were H3N2. Researchers at Northeastern University have linked the early climb to a variant carrying a mutation known as G155E, first detected in Japan in May, and preliminary laboratory work suggests the current vaccine should still recognize the circulating virus. Formal estimates of how well the vaccine is working this season are not yet available, and the CDC has not published a formal assessment of the match, so families should treat the early numbers as a warning rather than a forecast of how severe the winter will be.

Who should act first

For readers, the practical point of early flu season hospitalizations is timing rather than panic. The CDC recommends an annual flu vaccine for everyone aged six months and older, ideally by the end of October. Adults aged 65 and older had the highest hospitalization rate in the FluSurv-NET data, followed by adults in their fifties and early sixties and children under five. People in high-risk groups who develop fever, cough or body aches should contact a health care provider promptly, because antiviral drugs work best when started early, according to the agency. Many pharmacies offer walk-in vaccination, and many insurance plans cover flu shots, so checking with a plan or a local health department can settle the cost question before a visit.

A separate finding in the same CDC report deserves its own line, because it is easy to confuse with the seasonal wave behind early flu season hospitalizations. Health officials confirmed a single human case of bird flu in a dairy worker in Washington state, linked to exposure to infected cattle. The person was not hospitalized, and the CDC said human-to-human spread of that virus has not been identified in the United States. Officials urge farmworkers to get a seasonal flu shot so the seasonal virus and the bird flu virus are less likely to infect the same person at the same time. The next FluView report, covering the week ending October 24, is expected later this week and will show whether the early climb is continuing or leveling off.

Source: CDC FluView report, reported by Becker's Hospital Review in its summary of the same CDC data.