A team of researchers from the University of Hong Kong on Wednesday proposed harvesting convalescent plasma from recovered patients to treat patients with severe infections of influenza A/H1N1.

The convalescent plasma contains hyperimmune intravenous immunoglobulin, or H-IVIG, and experience from the 1,918 H1N1 flu pandemic and case reports on the treatment for severe H5N1 infections showed that such plasma was useful, the researchers said.

"Mice experiments also showed that antibody therapy was highly effective in the case of H5N1 infection," the researchers told reporters.

The influenza A1/H1N1, also known as human swine influenza, has led to a pandemic in over 170 countries and regions after its emergence in March this year, resulting in over 180,000 confirmed cases and over 1,400 mortality. The new virus is causing a mild disease in Hong Kong with relatively low mortality rate.

But the situation could be very different in the dry winter, the researchers warned.

"The mortality can be very high during the second wave as in the previous pandemic in 1918. This scenario has already taken place in countries in the southern hemisphere, including Australia, Argentina and Brazil (currently winter season)," they said.

Patients infected with severe influenza A/H1N1 have overwhelmed the intensive care services in these countries and the mortality rate has risen up to 6 percent in Argentina and Brazil, and 0.4 percent in Australia, compared with the mortality rate of 0.06 percent for the seasonal flu.

The efficacy of the treatment will be assessed thoroughly by a randomized, double-blind controlled trial since it is the world's first project using convalescent plasma on influenza A/H1N1 patients, the team said.

The team said each liter of convalescent plasma contains about 3 grams of H-IVIG, and each severely infected patient will need 4g/ kg of H-IVIG for treatment.

The team said it aimed to collect 420 liters of convalescent plasma, which will be enough to save about 63 patients in serious condition.

The researchers said they expected Hong Kong to report over 11, 000 more confirmed cases of influenza A/H1N1, and at least 1,300 of the patients will have to be hospitalized, 130 will require intensive care and 40 will die.

(Xinhua News Agency August 26, 2009)