Cost, resistance aired in HHS webcast on antivirals

Dec 17, 2008 (CIDRAP News) – Cost issues and the risk of viral resistance drew considerable attention today in an online presentation by federal health officials on their revised guidance regarding use of antiviral drugs in an influenza pandemic.

The Department of Health and Human Services (HHS) released two guidance documents this week, one on antiviral use in general and one on employer stockpiling of antivirals.

The general guidance says national and state antiviral stockpiles will be reserved mainly for treating the sick in a pandemic. It says that healthcare and emergency workers likely to be exposed to the sick should receive preventive antiviral treatment, with the doses provided by their employers.

The guidance on employer stockpiling supports the general guidance, recommending that businesses and organizations that employ workers likely to be exposed to infection provide prophylactic antiviral treatment for them. It also says that critical infrastructure employers should strongly consider providing antiviral prophylaxis for essential workers.

In today's HHS "PlanFirst" webcast, Dr. Benjamin Schwartz, MD, said the retail costs of the two recommended antivirals, oseltamivir (Tamiflu) and zanamivir (Relenza), range from about $50 to $80 per treatment course.

It may be possible for some groups, particularly healthcare organizations, to buy the drugs at a much lower cost through their state health department, but this would be limited to groups working with health departments as part of state pandemic planning, said Schwartz, who is senior science advisor with HHS's National Vaccine Program Office.

The other option for organizations seeking to buy antivirals, Schwartz said, is to participate in manufacturer programs that permit groups to reserve a supply by paying a small annual fee per treatment course. The manufacturer keeps the doses up to date, and in the event of a pandemic, the buyer pays the wholesale price for delivery of the product. Both Roche, maker of Tamiflu, and GlaxoSmithKline, maker of Relenza, offer such programs.

"It could almost be looked at as pandemic insurance," Schwartz said.

However, the cost of an antiviral program is more than just the per-regimen amount, HHS officials said. Workers who will receive the drugs will need medical screening, and there will be storage and dispensing costs as well.

The HHS acknowledges the risk that a pandemic virus develops resistance to the antiviral drugs. Schwartz noted that one of the three subtypes of seasonal influenza, A/H1N1, recently has shown increased resistance to oseltamivir.

"What is the implication of this?" Schwartz said. "I have to emphasize that this one virus is largely resistant, whereas other flu viruses that are circulating and the avian H5N1 virus remain susceptible to Tamiflu and Relenza. The types of changes, the mutations that have made the H1N1 virus resistant are unlikely to occur in a pandemic virus, so therefore we have not changed our recommendations for planning and stockpiling."

He also commented later, "It's possible that resistance might occur to one drug but not the other, and because of that, some level of diversification between the two products is wise."

The national stockpile of antivirals is about 80% oseltamivir and 20% zanamivir, according to HHS. The reason it's divided this way, said Schwartz, is that oseltamivir as an oral drug spreads throughout the body, whereas zanamivir is inhaled and therefore may work best in the respiratory tract.

"So there may be a theoretical benefit to Tamiflu," he said. "Tamiflu may also be a little bit easier to stockpile and there's a little more flexibility with use because you can go down to a lower age." (Oseltamivir is approved for treatment and prophylaxis in persons 1 year and older; zanamivir is approved for treatment of those aged 7 years and older and for prophylactic use in those aged 5 years and up.)

In response to a question, Schwartz said the national stockpile includes some pediatric doses of antivirals. Relenza does not come in a pediatric dose, he said, adding, "It's possible to open up the Tamiflu capsule and put the material from it in a syrup or liquid and dispense it in that way."

"I would reassure people that there is drug available for treatment of their children if their children become ill," he said.

Another question from a listener was whether school teachers and staff are included in the HHS recommendations for prophylactic antiviral treatment.

Lisa Koonin, MN, MPH, replied that schools would probably be closed early in a pandemic, a step that would help protect teachers and staff. Koonin is senior adviser in the Influenza Coordinating Unit at the Centers for Disease Control and Prevention.

In other comments, Schwartz said there is no evidence that the two antiviral drugs are harmful in pregnant women, "so for someone who's sick, certainly getting treatment would be important."

See also:

HHS news release about the revised antiviral guidance documents
http://www.hhs.gov/news/press/2008pres/12/20081216a.html

Dec 16 CIDRAP News story "Treatment comes first in HHS antiviral guidance"

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