Influenza rates remain high; vaccine, Tamiflu shortage reported

There are still high levels of influenza activity being reported across the country, but nationally, influenza activity is beginning to decrease, according to Thomas Frieden, MD, director of the CDC.

Overall, the proportion of outpatient visits for influenza-like illness was 4.6% for week 2 of 2013, which ended on Jan. 12; this is more than the national baseline of 2.2%. Thirty states and New York City experienced high influenza-like illness activity, and 48 states reported widespread geographic influenza activity. In addition, nine influenza-related pediatric deaths were reported during week 2, bringing the total number of pediatric deaths this season to 29.

Thomas Frieden

“That’s well below the 153 deaths reported in the 2003-2004 season, another H3N2 season, but we’re only in the middle of this season,” Frieden said during a media briefing today.

There have been reports of vaccine shortages. Frieden said vaccine manufacturers initially projected that 135 million doses would be available, but they are producing an addition 10 million doses. As of this week, 129 million doses have been distributed. Some formulations are out of stock, particularly ones for younger children. Providers can visit the Influenza Availability Tracking System to find out where they can order more vaccine.

Margaret Hamburg, MD, commissioner of the FDA, said there are now seven manufacturers approved to make influenza vaccine.

Margaret Hamburg

“The 145 million doses of vaccine available this year is twice the supply that was available several years ago, thanks to the combined efforts of the CDC, FDA and HHS,” Hamburg said.

Antiviral drugs, such as oseltamivir (Tamiflu, Genentech) are the best second line of defense against influenza, Frieden said, as they can reduce symptoms, shorten the duration of illness and prevent complications. It is especially important that high-risk patients, including the elderly, pregnant women, and young children and people with asthma, diabetes or heart disease, receive the treatment if they have influenza.

“The drugs work best if they are given within 48 hours of symptom onset,” Frieden said. “Among the highest-risk patients, even those that have a negative rapid flu test should be treated with antiviral medication because the rapid flu test does have false negatives.”

Hamburg said the FDA is working to make sure that antiviral medication is available for patients. However, there will be intermittent shortages of the oral suspension form of oseltamivir, which is prescribed to children, for the remainder of the season.

“FDA has been working with the manufacturers to increase supply,” Hamburg said. “We want to remind practitioners that there are directions on the label for pharmacists to make a liquid form of the medicine from capsules, if the liquid form is not available.”

To help avoid a shortage, the FDA has allowed Genentech to distribute 2 million units of oseltamivir 75-mg capsules that have an older version of the package insert. This is the same product currently in distribution and is not outdated, Hamburg said.