Of the organ transplant recipients in the H1N1 study, 16 per cent were sent to ICU. (CBC)

Organ transplant recipients who became infected with H1N1 seemed to do better if they were treated early with antivirals, researchers say.

Transplant recipients take immune-suppressing drugs throughout their lives to prevent rejection of their organs, but the drugs increase their risk of flu and other infections.

In Friday's online issue of the Lancet Infectious Diseases, Dr. Deepali Kumar of the University of Alberta in Edmonton assessed 237 adults and children who received organ transplants in Canada, Europe and the U.S. and who became infected with pandemic H1N1 between April and December 2009.

Early treatment with antiviral drugs, mainly Tamiflu or oseltamivir, was associated with reduced rates of ICU admission (eight per cent of those treated within 48 hours versus 22 per cent treated after 48 hours), as well as fewer hospital admissions, need for mechanical ventilation and death.

The virus resulted in a spectrum of illness ranging from mild to severe disease in the transplant recipients, just as did in the general population, the researchers found. Almost one-third of the patients studied contracted pneumonia.

Overall, 71 per cent of the patients were admitted to hospital, 16 per cent were sent to the ICU, and four per cent died.

"Starting treatment with antiviral drugs early is important for reduction of morbidity and mortality in this highly susceptible population. For example, during periods of transmission, transplant patients presenting with signs and symptoms that are compatible with influenza should probably start empirical treatment with antiviral drugs before the diagnosis is confirmed," Kumar and her co-authors concluded.

The researchers also found that almost a third of the patients studied report contact with an ill household member before their illness. In these cases, doctors might consider giving a prescription for antivirals to be taken as a precaution or as soon as symptoms start, the study's authors suggested.

The findings support the use of antivirals in immunocompromised individuals, but because of the potential for antiviral resistance, developing new anti-influenza drugs should be a priority, Per Ljungman from Karolinska University Hospital in Sweden said in a journal commentary accompanying the study.

There was no funding for the study. Several of the study's authors reported receiving research grants or working as a consultant for pharmaceutical companies.