American Medical News
By — Posted Feb. 4, 2013
An unusually early start to the flu season and an aggressive circulating strain of the virus is contributing to what many health professionals say is one of the worst influenza seasons they have seen in years.
“We're about halfway through, and it's shaping up to be a worse-than-average season and a bad season particularly for the elderly,” said Thomas Frieden MD, MPH, director of the Centers for Disease Control and Prevention, during a Jan. 18 telebriefing. The good news is that “there's still time to vaccinate,” he said.
Although reports of influenza-like illness seem to be leveling off nationally, some parts of the country, particularly the Northwest and Southwest, are continuing to show increases in flu-related illness, the CDC said Jan. 25.
Hospitalization rates have increased sharply among adults 65 and older in January, reaching a rate of 97 per 100,000 seniors, according to Jan. 29 CDC data. Pediatric flu-related deaths also continue to rise, with 37 mortalities reported to the CDC as of Jan. 19.
“That's well below the 153 deaths reported in the 2003-04 season, which was another H3N2 season, but we're only in the middle of our season,” Dr. Frieden said. “We expect to see both the number and rates of both hospitalizations and deaths rise further.”
Influenza experts say it's difficult to pinpoint why the 2012-13 season has been so aggressive. But they say a key factor is that influenza A(H3N2) is the virus strain that is predominantly circulating this season. The strain is associated with more severe flu seasons, said Michael Jhung, MD, MPH, medical officer in the CDC's influenza division.
Part of the problem with the H3N2 strain is that it has a tendency to change more than other influenza viruses from one season to the next, he said. As a result, people might be more susceptible to infection from H3N2 than other strains.
“It's been a few years since we've seen a lot of H3N2,” Dr. Jhung said. “That fact alone can contribute to why it's a more severe season, because people's immunity does tend to wane over time.”
Doctors' efforts to prevent and treat flu have been hampered by spot shortages of flu vaccine and the pediatric formulation of Tamiflu (oseltamivir) in certain communities, the CDC said.
The Chicago practice where internist Kimbra Bell, MD, works ran low on injectable influenza vaccine for a few days this season.
Injectable flu vaccine for young children is in extremely short supply at the Keller, Texas, practice where pediatrician Jason Terk, MD, sees patients. Part of the problem is that there is only one manufacturer, Sanofi Pasteur, that produces injectable influenza vaccine for children younger than 4, Dr. Terk said.
“Children who are 6 months to 12 months who can get the flu vaccine are our highest priority” to vaccinate, said Dr. Terk, chair of the Texas Medical Assn.'s Council on Science and Public Health.
About 133.5 million flu vaccine doses had been distributed as of Jan. 24, according to the CDC. In response to the spot shortages, manufacturers are producing additional flu vaccine doses, the CDC said. The companies project that they will have produced about 145 million doses by the end of the season, according to the CDC.
Among the vaccines that will be distributed to doctors is Protein Sciences Corp.'s Flublok, a new trivalent influenza immunization for people ages 18-49 that can be produced quickly because, unlike other flu vaccines, it is not grown in chicken eggs, the Food and Drug Administration said. The FDA approved the vaccine on Jan. 16.
Dr. Jhung said spot shortages of influenza vaccine occur every year, because it's difficult for manufacturers and doctors to predict the number of people who will choose to be immunized. He added that the increased attention the flu has received from the media and public health organizations due to its severity probably is leading more people than were expected to get the immunization.
There has been a significant burden of influenza where Dr. Terk practices in Texas. During a typical influenza season, he might have eight to 10 appointments a week for flu-related symptoms. But this season he has been seeing 15 to 20 patients each week for influenza-like illness.
In Chicago, the waiting rooms where Dr. Bell practices have been full with people who are sick with flu-related symptoms. Dr. Bell is a physician with Northwestern Memorial Physicians Group. On a few occasions, the practice was so swamped with patients that the office encouraged people to visit a nearby immediate care center that also is affiliated with Northwestern Memorial Hospital.
“At one point, you could go into that clinic and wait 15 minutes for an appointment. Now the waits there are approaching two hours,” said Dr. Bell, an assistant professor of clinical medicine at Northwestern University Feinberg School of Medicine. “I think [the increased wait] is in large part because of flu.”
The CDC is urging physicians to immunize their patients, particularly those who are 65 and older, who are still not vaccinated against the flu. The agency also encourages doctors to use antiviral medications for treatment of influenza. Antivirals ideally should be administered within 48 hours of onset of symptoms, the CDC said.
“The overall picture is clear,” said Lyn Finelli, DrPH, lead for the Surveillance and Outbreak Response Team in the CDC's Influenza Division. “This season is severe for seniors, who are being hit hardest in terms of serious illnesses and deaths. It's really important that these people seek care and get treated promptly.”