Swine Flu Q & A

Note: Guest blogger Matthew Hoffman, MD, has written for WebMD since 2006. He is currently a fellow in pulmonary and critical care medicine at Emory University, where he also completed medical school and residency.

As swine flu cases increase around the country, we are seeing some excellent questions from our readers about this disease. Here are answers to the most recent ones:

Anonymous said...
Is there any information on how long the H1N1 virus may live on hard surfaces? I believe that with HBV and HIV the lives of those viruses were seconds and weeks.

Dr. Hoffman: Great question. The H1N1 influenza virus is mainly transmitted through airborne droplets. Someone with the flu sneezes, coughs, or just talks, and someone else inhales the virus before the infected droplets settle to the ground.

Experts suspect that people also can catch swine flu (and seasonal flu) by touching surfaces contaminated with infected secretions (like shaking hands or touching a doorknob). Far fewer people catch flu this way, compared to airborne transmission.

Influenza viruses have been shown to survive on surfaces for 2 to 8 hours. However, that doesn’t mean they’re lurking on every countertop and faucet handle. Frequent hand washing, avoiding contact with sick people, and avoiding touching your nose, mouth and eyes are the best ways to avoid swine flu.

Anonymous said...
once diagnosed with swine flu and you have recovered can you contract the virus again?

Dr. Hoffman: No. Once you have had H1N1 influenza, your body develops antibodies against multiple parts of the virus. If you were then re-exposed to swine flu, your body would quickly destroy the virus and you would not become ill. (This assumes you have a normal immune system.)

Remember, though, that influenza viruses are constantly changing and combining with each other into new forms. (That’s why you need a new flu shot every year.) New seasonal flu viruses, and possibly swine flu viruses, will eventually develop. Immunity against the current H1N1 doesn’t necessarily provide immunity against any other form of influenza.


Anonymous said...
I want to know the answer to the second question. We think our college-age daughter had H1N1 this summer (all the symptoms--every one) but the initial rapid flu test had come back negative. Should she be getting vaccinated, since we're only 99% positive it was H1N1?

Dr. Hoffman: If your daughter is younger than 24, she should probably get vaccinated despite her previous illness. The Centers for Disease Control recommend vaccination against H1N1 influenza for anyone in these groups:

• Aged 6 months through 24 years old
• Pregnant women
• Regular close contacts of children younger than 6 months old
• Health care workers
• Anyone aged 25 to 64 with chronic illnesses

Rapid flu tests are only about 40-70% accurate at diagnosing influenza. In other words, a normal result still leaves about a 50-50 chance of having swine flu. Although your daughter may well have had swine flu earlier this year, you can’t be sure without a positive culture result.

Griph said...
I have been Diagnosed by my doctor with the Swine Flue, will I die?

Dr. Hoffman: It’s very unlikely that you will die from swine flu. In this country, the H1N1 influenza virus seems to be only slightly more dangerous than the regular seasonal flu.

People at higher risk of serious illness from swine flu include pregnant women and people with chronic illnesses. However, it’s true that unlike seasonal flu, swine flu has caused the deaths of a small number of otherwise healthy young people. I’m glad you were feeling well enough to write—most likely, that means you’re doing OK.