Friday, January 19, 2007

Antivirals vs. vaccines: Which one is the right answer in the fight against a flu pandemic?

As health officials around the world discuss the continuing struggle to contain cases of bird flu, both antiviral drugs and vaccines are mentioned as ways to fight the disease. So what's the difference, and which one is the best solution?

The main difference between the two is that antiviral agents are drugs used to treat people or animals once they've become sick, while vaccines are used to prevent diseases in those who are still healthy.

Right now, there are four antiviral drugs available to fight the seasonal flu. Of these, two have been shown to fight infections with H5N1, the bird flu virus that is infecting some birds and people around the world. In the event of a pandemic — which is essentially a widespread outbreak of infectious disease, possibly on a global scale — antivirals may be used to treat sick people.

Antiviral agents can in some cases shorten the time sick people are unwell, but there are a lot of limitations to these drugs: They must be taken within two days of becoming sick, and they don’t work for everyone. Antivirals are not available over-the-counter and must be prescribed by a doctor, so it may be too late to use them if you delay going to the doctor or hospital once you are sick.

Vaccines on the other hand, are of no use once people are already sick. To understand how a vaccine works, we must first understand how our bodies defend themselves against disease. Let's say the body is the defensive lineup of a football team, and the opposing team is what makes us sick. The end zone, which is the defense's job to protect, is our health. When exposed to a new play from the rival team, the defense is unprepared, and the opposing team is able to break through. If the team is strong enough to reach the end zone, we become infected and begin to feel sick. However, once exposed to this new play, our defenders remember it. When the same play is used again, the defense is able to recognize it earlier and is more prepared to block it from advancing.

A vaccine uses this idea of a "memory" to prepare our bodies for attack. A vaccine is made from a weaker form of the opposing team, such as its third string or benchwarmers. This weaker team is still able to penetrate our defense, but never reaches the end zone to make us sick. This minor exposure to the opposing team’s play still allows us to remember it so we are prepared to fight when the stronger first string tries to use it again.

And as we've mentioned before, there is no vaccine available yet against the H5N1 bird flu. There are a lot of fake bird flu vaccines being advertised, but none of them are legitimate. If you aren't sure what you need to prepare for bird flu or a flu pandemic, ask your doctor or health care professional for advice.

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