WASHINGTON — After an early outbreak, the nation’s flu epidemic is showing some signs of weakening, but government experts say it’s too soon to tell whether the worst has passed.
“The only thing predictable about flu is that it’s unpredictable,” said Dr. Tom Frieden, director of the U.S. Centers for Disease Control and Prevention. “Only time will tell us how long our season will last and how moderate or how severe this season will be in the end.”
As of Friday, 24 states and New York City reported high levels of influenza-like illness among outpatient hospital visitors. That’s down from 29 last week, according to new data released Friday by the CDC.
States reporting high levels of patients with flu-like symptoms include Georgia, Illinois, Kansas, Louisiana, Mississippi, Missouri, North Carolina and Texas.
Likewise, the portion of outpatient hospital visitors reporting flu-like symptoms fell to 4.3 percent last week, down from 6 percent the previous week.
But 47 states reported that influenza had been found in more than half of their counties last week, up from 41 states the week before. Only California and Mississippi reported regional flu activity, and Hawaii had only sporadic outbreaks. And for the first time this flu season, the 7.3 percent of deaths caused by pneumonia and influenza topped the 7.2 percent threshold for an epidemic in a weekly CDC analysis of 122 cities.
The conflicting data isn’t surprising because flu activity typically ebbs and flows across regional, state and even county lines as it spreads across the country during its usual three-month run, Frieden said.
So it’s hard to tell whether the reported declines are part of a new downward trend in the virus spread or just an anomaly, because the Dec. 30-Jan. 5 reporting period included part of the holiday season when fewer people visit the doctor.
“The declines may be because the disease level has peaked in some areas and is coming down,” Frieden said. “Or next week we may see that go up again. But we are seeing a decrease in the most recent week in some areas, while other parts of the country, particularly in the West, appear to continue to be on the upswing.”
The mixed reporting signals come as the number of children killed by the flu rose from 18 to 20 last week. Total deaths won’t be tallied until the end of the flu season, but the virus typically kills thousands and sometimes tens of thousands of Americans each year.
This year’s early flu epidemic is reminiscent of the 2003-2004 flu season, which peaked in November and December and had high child and adult mortality rates.
“I don’t know how this year will compare in terms of severity or in terms of length or in terms of when the peak is (compared) to that year yet, but we’ll know in a few months,” said Dr. Joseph Bresee, who heads the influenza division of the CDC’s epidemiology and prevention branch.
While most of the nation is seeing elevated flu activity, the western part of the country is only now starting to see notable outbreaks.
Florida, South Carolina and Washington were among 16 states with moderate flu activity levels. Five states, including Alaska and Idaho, had low activity levels, while California and Kentucky were among five states with minimal levels of activity.
Cities and towns are responding to the outbreak in different ways. The city of Boston declared a health emergency earlier this week, while some hospitals have set up tents to house a surge in sick patients.
Nationally, some parents and caregivers are reporting spot shortages of the children’s liquid formulation of Tamiflu, an antiviral medication that shortens the duration of the flu when taken within two days of developing symptoms.
Fortunately, pharmacists can reconstitute children’s Tamiflu from the 75-milligram pills taken by adults, said Bresee. Drug companies are working to remedy the shortage, but there’s no shortage of Tamiflu for adults, Bresee said.
The CDC continues to urge all people ages 6 months and older to get vaccinated, even though some will still become infected. Overall, Frieden said 62 percent of people who get vaccinated don’t develop flu symptoms that require professional medical care. But against this season’s dominant Influenza A virus, the figure drops to 55 percent, while the vaccine is 75 percent effective against the less-prevalent Influenza B virus.
That success rate is “in line” with the historic 50 percent to 70 percent rate of effectiveness for seasonal flu vaccines, Frieden said. The vaccine formula will not be altered for the current season, he added. The flu vaccine is most effective in young, healthy people and less effective in older people and those with compromised immune systems or underlying medical conditions.
“The flu vaccine is far from perfect, but it’s still by far the best tool we have to prevent the flu,” Frieden said.
At least 112 million Americans, or about 37 percent, have been vaccinated thus far. Of the 130 million doses produced, about 128 million already have been distributed.
Officials urge all Americans to wash their hands often and to stay home if they become sick with a cough and fever. Sick children should be kept home from school. Those who develop a fever, cough or become very ill should contact a doctor and seek early treatment with antivirals.
“Only time will tell us how long our season will last and how moderate or how severe this season will be in the end,” Frieden said.