Flu Season Gets an Early Start, CDC Says
Influenza activity through November in the United States was much higher than last year at this time, according to surveillance data reported today at a Centers for Disease Control and Prevention (CDC) telebriefing. In fact, "we're seeing the earliest start to the flu season since 2003-2004, excluding the [H1N1] pandemic," said CDC Director Thomas Frieden, MD, MPH.
So far, the hardest hit states have been those in the south-central portion of the country, including Alabama, Louisiana, Mississippi, Tennessee, and Texas, and moderate levels of influenza activity have been reported in Missouri and Georgia, "but it's just a matter of time before other parts of the country are hit," according to Melinda Wharton, MD, acting director of the CDC's National Center for Immunization and Respiratory Diseases.
Moreover, officials think that when the influenza hits this year, it will it hard. "Although the course of every flu season is unpredictable, [with] this year's early start and the specific influenza subtypes circulating, this could be a bad year," Dr. Frieden stated.
"The subtypes we're seeing, particularly H3N2 [the same strain that was prevalent in 2003-2004], are generally associated with more severe flu symptoms, but only time will tell," Dr. Frieden said. "The only thing we know for certain is that vaccination is the best protection, and this year the vaccine is a good match, at approximately 90%, for the strains that are in circulation."
To date, approximately 37% of the US population aged 6 months and older have been vaccinated, Dr. Wharton reported, with the highest rate of vaccination (45%) seen in children.
"There are already more than 120 million doses of vaccine out there to be had, and there is no indication that there will be a shortage, so we are encouraging everyone to get vaccinated, particularly those who are historically most vulnerable to flu-related complications, including children, pregnant women, and healthcare workers," Dr. Wharton said.
In terms of vaccine coverage, "we are holding gains from last year, particularly in these key populations, but we need to make further gains," Dr. Frieden said, noting the identification of multiple "interesting" trends.
For example, "nearly half of all pregnant women have been vaccinated already, and the biggest predictor of whether a pregnant woman will get vaccinated is whether her obstetrician offers her the vaccine in the office." In fact, nearly 75% of pregnant women who have been vaccinated received the vaccine during an obstetric visit.
Vaccine coverage among healthcare workers is high, with 80% to 90% of all physicians, nurses, and pharmacists having already been vaccinated this season, according to Dr. Frieden. "Where we are falling short is among allied healthcare workers and others in the healthcare system, as well as in nursing homes," so more focused efforts have to be targeted to this population, he said.
Among adults in general, the new surveillance data indicate that work sites and pharmacies are major sources of vaccinations for adults, "with more than one third of the vaccines being given at one of these sites."
Although the influenza season started early, it is not too late to get vaccinated, particularly because "we don't know yet when the peak will be. What we're seeing is the beginning of the uptick," Dr. Frieden stressed.
Specific surveillance data from the CDC's indicates that for the week ending November 24 approximately 2.2% of visits to physician offices in the US overall and 4% in the south-central region of the country were for influenza-like illnesses. Further, the percentage of respiratory tests found to be positive for influenza during the week was 15.2%, and the percentage of deaths from pneumonia and influenza was 6.3%. Two pediatric influenza deaths have been reported for the season thus far.
Current vaccination reports are also available on the CDC Web site.
The CDC recommends that all people aged 6 months and older be immunized against influenza. "We are optimistic about the number of people who have already received the flu vaccine, but there are still many others who need to be protected," Dr. Frieden said.
Dr. Frieden and Dr. Wharton have disclosed no relevant financial relationships.