Convalescent plasma therapy using plasma from patients who have recovered from an infection to treat those with the same infection has been used to treat multiple diseases. However, the efficacy of this treatment in patients with severe 2009 H1N1 influenza is unknown. A study published in the February 15 issue of Clinical Infectious Diseases suggests that convalescent plasma may reduce the death rate in patients severely ill with this type of influenza.

From September 2009 through June 2010, patients from a hospital cluster in Hong Kong with severe 2009 H1N1 infection requiring intensive care were recruited for the study. Of the 93 patients in the study, 20 received the plasma treatment. Prior patients who had recovered from H1N1 infection provided the convalescent plasma for the study. The 73 members of the study who declined the treatment were the study controls.

Mortality in the treatment group was 20 percent, compared to 55 percent in the non-treatment group. The viral load in the treatment group also decreased at a higher rate than in the control group. None of the patients developed adverse events from the treatment. "One of the benefits of convalescent plasma treatment in patients with severe influenza A infection is that it does not suffer from the problem of drug resistance," said study author Kowk-Yung Yuen, MD, of the University of Hong Kong in China. "Additionally, it would remain effective until the virus has changed significantly enough to affect immunity. This form of treatment may be useful in future novel viral infections." NOTE: The study is available online. It is embargoed until 12:01 a.m. EST on Wednesday, Jan. 19, 2011: "Convalescent Plasma Treatment Reduced Mortality in Patients With Severe Pandemic Influenza A (H1N1) 2009 Virus Infection"

Sources: Oxford University Press (OUP), AlphaGalileo Foundation.