The CDC and flu meds: Don t get your hopes up

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We were somewhat surprised to see today s recommendation by the CDC, which urged doctors to treat flu more aggressively. If only it were that simple.

This advisory is a result of a bad flu season, coupled with a poor match of this year s vaccine with circulating influenza strains. The match is so poor that the CDC estimates that only about one-third of predominant strains are covered far worse than last year s vaccine, which was criticized for covering roughly 60 percent of strains.

Screen Shot 2015-01-12 at 1.47.05 PMWe were somewhat surprised to see today s recommendation by the CDC, which urged doctors to treat flu more aggressively. If only it were that simple.

This advisory is a result of a bad flu season, coupled with a poor match of this year s vaccine with circulating influenza strains. The match is so poor that the CDC estimates that only about one-third of predominant strains are covered far worse than last year s vaccine, which was criticized for covering roughly 60 percent of strains.

As we have pointed out in the past, this is not anyone s fault. Rather, it is a function of the difficulties involved in getting the match right. In order to allow time for manufacturing the vaccine, the strains must be predicted six months in advance, based on which strains are predominant at the time according to surveillance data collected from more than 100 countries. The WHO then makes a recommendation for the composition of the vaccine.

This year, the match between the vaccine and predominant circulating strains is very poor, so the vaccine will not protect as many people. But it is still the best option available.

The efficacy of the 2014 vaccine is bad enough that the CDC is urging doctors to make greater use of the two antiviral drugs that supposedly work to minimize the effects of flu.

But, as he pointed out in his 2012 piece in Medical Progress Today entitled Tami-flu the Coop, ACSH s Dr. Josh Bloom is less than impressed with the actual benefits of Tamiflu and Relenza the two drugs that are sometimes used. (A new drug called Rapivab was approved last month for intravenous use in hospitalized patients. All three drugs work by the same mechanism: inhibition of neuraminidase an enzyme that enables newly formed virus particles to escape from the host cell.)

He says, There has long been a controversy over whether these two drugs work at all. And even if they do, their efficacy is very limited. The CDC obviously knows all of this, but for the lack of anything else to do, is now quite enthusiastic about using them. I wonder how much of this is motivated by their image as opposed to real medical evidence.

He is not alone. Scott Gavura, a pharmacist who writes for the blog Science-Based Medicine, doesn t seem all that impressed. Back in April he wrote, "If you have a tidal wave coming at you and someone hands you a pair of water wings, you ll probably take them because they might help you and they won't do you harm." Not exactly a ringing endorsement.

But that sounds like pure joy compared to what Dr. Paul Bunce, an infectious diseases specialist at the University of Toronto Hospital, has to say: "We feel really helpless, and it s easier to give something than nothing."

Dr. Tom Frieden, director of the CDC disagrees. He recently said, This flu season is shaping up to be a severe one, especially for older people and young children and those with underlying conditions...Antiviral flu medicines are underutilized, but if you get them early, they can keep you out of the hospital and might even save your life.

They might, but they also might not. Data on the effectiveness of flu antivirals have been interpreted in a variety of ways. At best they can reduce reduce symptoms (even this has been debated) and decrease the duration of infection from about 7 days to 6. And the drug must be taken within the first two days of when symptoms start.

Dr. Bloom comments, The science used to design these drugs was elegant and sophisticated. But nature does not care one bit about this. They just don t work very well. Roll up your sleeve and hope.