September 24th, 2009
10:40 AM ET

Do I need the H1N1 vaccine if I think I already had the virus?

As a regular feature of CNNhealth.com, our team of expert doctors answers readers’ questions. Here’s a question for Dr. Gupta.

From Birgitta in Newcastle, Washington:

I think I already had the swine flu but do not know for sure if it was swine flu, do I take the vaccination anyway? Is it safe to take if I suspect that the flu I had was swine flu?


Tens of thousands of people right now, like Birgitta, are suffering from or getting over the H1N1 virus. Those numbers will continue to swell as the flu season wears on, and these questions will inevitably come up over and over again.

Incidentally, I can relate. I contracted the H1N1 virus recently while reporting on the war in Afghanistan, and I was miserable for days. I got my immunity to H1N1 the hard way, so I can take a pass on the vaccine this year. But what about people who are not as sure, like Birgitta?

The bottom line is, unless you got a laboratory test confirming it, you cannot be sure that you actually got the H1N1 virus. There are several strains of influenza floating around out there this season, two of which are H1N1 and seasonal influenza. There are a handful of other strains you could have contracted.

The old adage, "Better to be safe than sorry," may apply here. Unless you're sure you had H1N1, the Centers for Disease Control and Prevention recommends that you get vaccinated. Even if you did, in theory, get H1N1 the CDC reports no evidence that subsequently getting the H1N1 vaccine would cause problems for you.

You can think about your vaccination like an insurance policy. If you did have H1N1 during your recent illness, then you're protected. If you did not, you're also protected.

If you're wondering when the vaccine will be available, the largest shipment of H1N1 vaccine is scheduled for mid-October. By then, the first 45 million doses of the vaccine will be ready, with another 20 million doses shipped out each week until December.

And don't forget, the CDC recommends that you get the seasonal flu vaccine as well.

About this blog

Get a behind-the-scenes look at the latest stories from CNN Chief Medical Correspondent, Dr. Sanjay Gupta, Senior Medical Correspondent Elizabeth Cohen and the CNN Medical Unit producers. They'll share news and views on health and medical trends - info that will help you take better care of yourself and the people you love.