MONDAY, Sept. 7 (HealthDay News) -- The new H1N1 swine flu vaccine appears to be as safe as the seasonal flu variety, according to experts from the U.S. National Institute of Allergy and Infectious Diseases; and, intravenous use of the antiviral zanamivir (Relenza) may provide a lifesaving alternative for severe cases of H1N1 pneumonitis, according to a report published online Sept. 4 in The Lancet.

Anthony S. Fauci, M.D., director of the U.S. National Institute of Allergy and Infectious Diseases in Bethesda, Md., and colleagues designed a trial to test the vaccine on healthy adults beginning on Aug. 7, while another trial involving children began Aug. 18. Although no red flags have been seen, it was acknowledged that rare side effects often only emerge after millions of people have been vaccinated.

In the case report of a young woman treated successfully with unlicensed intravenous zanamivir along with corticosteroids for H1N1 pneumonitis, Michael Kidd, Ph.D., of University College London Hospitals NHS Foundation Trust, and colleagues had unsuccessfully attempted treatment with oseltamivir and broad-spectrum antibiotics.

"Since her inflamed, atelectatic lungs were probably impeding adequate drug absorption, and clinical improvement was not forthcoming, we decided to use intravenous (unlicensed) zanamivir. Our patient recovered with no side-effects," Kidd and colleagues conclude. "Although this is a single case report and direct cause and effect cannot be confirmed, the improvement in clinical status following intravenous zanamivir encourages prompt further investigation, both alone and in combination with high-dose methylprednisolone."

The zanamivir for The Lancet case report was provided by GlaxoSmithKline.

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The Lancet Case Report (subscription or payment may be required)