Some Dutch scientists have stirred controversy by saying that maybe kids should skip seasonal flu vaccine this year. But other health experts reject the idea, the Associated Press reported. The theory came from a group of scientists at Erasmus University in the Netherlands. The journal Lancet published their commentary online October 30. The scientists cited the 1957 Asian flu pandemic. They said people infected with seasonal flu that year were less likely to catch Asian flu. In mice and ferrets, having seasonal flu also seems to increase immunity to other types of flu, they said. But health officials said there's no proof that letting children get seasonal flu will protect them from the current pandemic, H1N1 (swine) flu. Children are one of the groups most likely to get seriously ill from flu. Also, experts noted that most people in Mexico don't get flu shots. But that's where the swine flu pandemic started, back in the spring.

By Mary Pickett, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

Since I am a doctor and a mom, parents in my neighborhood want to know whether I have decided to have my kids vaccinated against the flu. I have my children prepared to receive three vaccinations this year, I tell them. That means two doses of H1N1 vaccine for my kids who are under 10, and one dose of seasonal flu.

But now I am hearing a new buzz from moms on the soccer field and at my school. A set of researchers has suggested a worrisome theory. They say getting the seasonal flu vaccine might interfere with your getting the most protection against H1N1 flu. Could this be true? Does this give us a good reason to skip out on seasonal flu shots this year?

No, it does not, in my opinion. And a large majority of flu experts say the same. I am sticking with my plan to get my kids (and myself) both kinds of flu vaccines. The thinking behind the controversial theory is that illness with seasonal flu might offer a little bit of protection against H1N1 flu. If this were true, there would be a potential benefit -- late in the H1N1 season -- for people who had suffered through seasonal flu.

The major proteins that help define a flu virus as H1N1 are different from the usual seasonal flu. Therefore, there is truly no overlap in protection from the different vaccines. But when our immune system reacts against a real virus, we react against all kinds of proteins on the virus surface. These researchers think that some of these other proteins (the ones not targeted by the vaccine) may be similar on both seasonal and H1N1 flu. Their theory is that immunity against seasonal flu might cross over to help against H1N1, too.

There are several problems with the theory:

• There is no proof that seasonal flu infection provides any meaningful protection against the H1N1 strain. One of the reasons that H1N1 is special is that we have gained little or no immunity against it from our encounters with other strains of flu. Some experts have pointed out that Mexico has low rates of seasonal flu vaccination. Yet H1N1 still caused widespread infection in Mexico and many complications and deaths.



• If you are vaccinated against both flu types, you are protected against both. Absolutely, this is better than being protected against one flu only! Earlier in the fall, there were concerns that the H1N1 vaccine might stay in short supply. But these worries are being calmed as more vaccine becomes available.



• The H1N1 season has already started. Seasonal flu season has not. You may not encounter both types of flu this season. But if you do, odds are that you will be exposed to H1N1 weeks or months before you encounter seasonal flu.

What Changes Can I Make Now?

I don't recommend you make any changes -- as long as you have been planning to have your kids fully vaccinated. I am sticking with my plan to get my kids (and myself) both kinds of flu vaccines.

My kids are too young to appreciate the value of vaccinations. So they are not pleased with the three vaccine plan. As much as I hate seeing my kids flinch, I am telling them that one of the vaccines will have to be a shot.

You can't get the nose spray form for both the H1N1 and the seasonal flu unless you space them apart by four weeks, according to the U.S. Centers for Disease Control and Prevention. The first and second doses of H1N1 must be spaced apart by at least three weeks. If you add another four weeks between H1N1 and seasonal flu vaccines, it adds up to a seven week project. I am not willing to wait that far into the flu season so that my kids can have their third vaccine as a nose spray.

What Can I Expect Looking to the Future?

The people who are most vulnerable to seasonal flu are elderly adults, and people who have chronic illnesses. What is one of the most effective ways that we can protect our elderly? Vaccinate our children against seasonal flu.

Parents are going out of their way to schedule flu vaccination this year because of H1N1. Perhaps this year we will have record-breaking childhood vaccination rates against seasonal flu, too. This may help to make seasonal flu much less lethal for our elderly than it has been in other years.