July 28, 2009

Swine Flu Antivirals Work Best When Treated Early

Italian researchers said on Monday health officials need to do a better job of quickly tracking and treating new H1N1 flu cases in order to make the best use of antiviral drugs, Reuters reported.

Stefano Merler of the Bruno Kessler Foundation in Trento, Italy and colleagues reported that having stockpiles of drugs does little good if people do not get them within the 24 to 48 hour window when they work best.

The researchers reported in the BioMed Central journal BMC Infectious Diseases that their study also highlights the importance of the early detection of cases.

"Great effort should be made in order to establish a surveillance system able to detect and treat cases as soon as possible since a delay of more than 24 hours could make both antiviral treatment and prophylaxis very inefficient," they wrote.

Meanwhile, the World Health Organization has stopped counting individual H1N1 swine flu cases because it has spread so fast "“ something experts are afraid might encourage national health authorities to cut back on testing.

But if governments can track cases, quick use of drugs could help a great deal, according to Merler's team.

Providing antiviral drugs to the elderly to protect them from infection would not save many lives, but treating younger people would, according to the team's mathematical models.

Only one commercial test from Quest Diagnostics and two government tests are licensed in the United States for diagnosing H1N1 flu quickly.

Countries are advised to stockpile enough antivirals to treat 25 percent of their populations, as per recommendations from the WHO.

Such antivirals include zanamivir, made by GlaxoSmithKline under license from Biota Inc. and sold under the brand name Relenza, and oseltamivir, made by Roche AG under license from Gilead Sciences and sold under the brand name Tamiflu.

While both drugs can reduce the risk of death among people at serious risk of flu complications, such as the very old, the very young, people with asthma and other chronic diseases and pregnant women, they must be given within the first day or two.

Experts say this makes prompt diagnosis important.

Each vaccine can also be used to prevent infection, but most health experts say it is important to do this only for people who are both at high risk of complications and who have been in close contact with someone with a confirmed H1N1 infection.

Many policies recommend using these drugs as prophylactic agents in nursing homes, for example, where viruses can sweep through and kill many frail residents.

But the researchers said in a pandemic, with the drugs in high demand, this strategy may not save enough lives.

Merler said his team's work demonstrates that even in countries where the antiviral stockpile is not sufficient to treat 25 percent of the population -- the minimum level suggested by the WHO -- it is possible to reduce morbidity and excess mortality by prioritizing the use of antivirals by age.

For example, Italy only had enough drugs to treat 12 percent of its population.

Similar to what has been seen with the H1N1 pandemic, their model included data from the last three flu pandemics, in 1918, 1957 and 1968. In 1918, the virus affected more young adults and older children than usual.

The researchers concluded that the only way to save lives with a small stockpile of drugs was to treat everyone who was infected, and give the drugs prophylactically to younger people.


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