“How effective are flu vaccines for children?”

Very effective

Flu vaccine effectiveness varies from year-to year, by age and underlying medical condition. Effectiveness is somewhat lower in children under age 2 and gets higher with aging towards adults. As said before a number of factors influence effectiveness range from about 30 to 70%. Since flu vaccines are proven safe a drop in overall population vaccination rate will result in an increase in infections and also increase in infections with hospitalizations and severe disease or death.

60% for mild disease, 85% for severe disease

In general, flu vaccines are slightly more effective for children than they are for adults; vaccine efficacy wanes even more in the elderly. Vaccine efficacy of flu vaccines depends, to a great extent, upon how well the vaccine strain matches the actually circulating strain. The virus that causes the flu is constantly evolving. We have to predict what strain will arrive on our shores by looking at the viruses that are circulating earlier in the Far East. It takes a while to manufacture the vaccine, so sometimes by the time the virus actually arrives on our hemisphere, it has mutated slightly away from the vaccine protection. Some years, on the other hand, the match is very good; in those years the flu vaccine works better.

Please remember that the flu vaccine only protects against influenza viruses. It cannot and does not prevent infection with common cold viruses, of which there are literally hundreds. Sometimes people think that they got the flu despite the vaccine when they really just got one of the other common cold viruses. Also, flu vaccine does not protect against the viruses that cause vomiting and diarrhea, so, if you end up with one of those, it does not mean the flu vaccine failed.

Randall Fisher, M.D.