The approximate midpoint of the 2014-2015 flu season has been reached, disease remains widespread, and antiviral flu medications remain underutilized, according to the Centers for Disease Control and Prevention.
As predicted, this season is proving particularly severe due to the predominance of antigenically drifted H3N2 virus strains, and the CDC is urging clinicians to maintain a high index of suspicion for flu and to prescribe antivirals earlier and more aggressively for patients presenting with flulike illness – especially young children, those over age 65 years, and those with underlying conditions, even if their symptoms are mild, CDC Director Thomas R. Frieden said during a press briefing.
A health advisory on the topic was issued Jan. 9, he noted.
“The CDC has recommended the use of antiviral drugs as an adjunct to vaccination. They are the only medicines that can specifically treat influenza illness, and in the context of an H3N2 predominant season with a less effective vaccine, treatment with antiflu drugs is even more important than usual,” he said, referring to the two neuraminidase inhibitors currently approved for treating influenza: oseltamivir and zanamivir.
About two-thirds of the H3N2 viruses analyzed this season are different from the H3N2 virus included in this year’s vaccine, which is why the vaccine is expected to have reduced effectiveness, he explained.
This makes early antiviral treatment all the more important, he added, noting that treatment within 2 days of symptom onset is optimal, but later treatment can also offer benefit.
“CDC scientists have looked very carefully at the use of influenza drugs in the clinical setting, and the conclusion is clear: They work, but they aren’t being used nearly enough. They can reduce symptoms, shorten duration of illness, and prevent serious complications,” he said.
Early treatment may help patients avoid hospitalization and could be life saving, he added.
Many patients are unaware that effective prescription treatments exist, and many doctors are not using the treatments as recommended. In one study, fewer than one in five eligible high-risk patients received treatment.
“So we’re expanding our efforts to reach clinicians about reminders about the importance of these drugs,” he said, noting that if high-risk patients with underlying conditions such as asthma, sickle cell disease, renal disease, or diabetes were treated, “tens of thousands of hospitalizations, and thousands of deaths could potentially be prevented.”
Dr. Frieden suggested that clinicians consider phone triage lines for high-risk patients to discuss symptoms over the phone and to “facilitate early initiation of treatment.”
An antiviral prescription can be provided without testing and before an office visit, he added.
The typical flu season lasts about 13 weeks on average, and the season began about 7 weeks ago. The continued high rate of H3N2 disease has had the greatest impact on older adults; that is typical of such seasons, which often involve a higher rate of hospitalizations and deaths.
In fact, hospitalization rates in the over 65 age group are rising sharply, Dr. Frieden said.
Last week the rate was 52 per 100,000 population, and this week the rate was 92 per 100,000 population. The cumulative rate 2 years ago when H3N2 viruses last predominated was 183 per 100,000, he noted.
“We wouldn’t be surprised to see something very similar this year,” he said.
Young children are also severely affected; thus far in the season there have been 26 reported pediatric flu-related deaths.
However, there are early signs that infection rates are declining in areas where the season started earlier, such as the Southeast, and the number of patients presenting to a doctor with flulike symptoms has also declined slightly, but it is too soon to tell whether disease activity has peaked, he said, stressing that “we still have several weeks of flu activity ahead.”
It’s not too late to get vaccinated, and despite the reduced efficacy of this year’s vaccine against the circulating H3N2 strains, vaccination may still offer some benefit.
“There are other strains out there as well,” he said, noting that a proportion of cases from other strains, such as influenza B, tend to occur late in the season, and this year’s vaccine offers a good match for influenza B viruses.
Pneumococcal vaccination is also important, particularly for older adults and those at high risk , he said.
Last September the CDC announced a new recommendation that all adults over age 65 years should get two different pneumococcal vaccines. Such vaccination may help prevent flu-related pneumonia.
Patients with the flu or flulike illness should be advised to cover their cough and to stay home from work or school to protect those who are most vulnerable to the flu, he said.