Lung Disease & Respiratory Health Center

Possible SARS Treatment?

Dec. 23, 2003 -- Interferon may have saved lives during last winter's SARS outbreak, researchers say.

Carried by airplane passengers, the deadly disease rapidly spread from Asia to North America. Before intensive public-health measures snuffed out the epidemic, SARS killed 774 people.

The illness baffled doctors, who had no specific treatment. But when scientists finally isolated the SARS virus, doctors at last had a clue. Interferon has antiviral activity. It's been a huge benefit to people with hepatitis B and C viruses. And in the test tube, a kind of interferon called Infergen (made by Intermune Corp. of Brisbane, Calif.) inhibited the SARS virus.

It was a race against time. While these lab tests were under way, people were dying. Toronto was one of the cities hit by the epidemic. On May 29, 2003, Canadian health authorities gave doctors a green light to treat SARS patients with Infergen.

How SARS Kills

Doctors think a one-two punch is what makes SARS so dangerous. First, the SARS virus multiplies rapidly, killing lung cells as it grows. Then the body, all its alarms ringing, mounts an all-or-nothing immune response. Unfortunately, this overexuberant immune response throws out the baby with the bath water. It causes even more extensive lung damage and, sometimes, death.

This immune response is why most SARS patients get treated with steroids, which put a damper on the immune system. There's no actual proof that this works, but because it seems reasonable, all hospitalized SARS patients get steroid treatment.

Steroids Plus Interferon The Key

At Toronto's North York General Hospital, Mona R. Loutfy, MD, MPH, and colleagues were ready to act. On May 29, 2003, they started adding Infergen to the steroid treatment for SARS. They treated nine patients with this combination treatment and compared them with 13 patients who got steroid treatment alone.

Among the 13 steroid-only patients, five went on to intensive care, three needed mechanical breathing support, and one died.

Among the nine patients treated with Infergen plus steroids, three went into the intensive care unit, one needed breathing support, and none died.

These preliminary studies suggest that treatment with Infergen and steroids more quickly improves lung X-rays and oxygen levels in the body than treatment with steroids alone, Loutfy and colleagues report in the Dec. 24/31 issue of TheJournal of the American Medical Association.

Loutfy and colleagues suggest the interferon may work by decreasing the amount of SARS virus in the lungs. If given in time, this would lessen the body's drastic immune response to the virus. They also suggest that the interferon may help steroids limit harmful immune responses.

SOURCE: Loutfy, M.R. TheJournal of the American Medical Association, Dec. 24/31, 2003; vol 290: pp 3222-3228.