There’s been a particularly large outbreak of the flu in many parts of the country, and as a result we’re starting to see shortages of the flu vaccine. If you haven’t gotten vaccinated yet you might want to get moving.

Chemicals can make vaccines less effective in children.

Environmental pollutants such as PFCs have been used in nonstick coatings, stain-resistant fabrics and some food packaging for decades and have been detected in blood tests of children.

Normally, a vaccine causes the production of lots of antibodies to a specific germ. But Grandjean says the response to tetanus and diphtheria vaccines was much weaker in 5-year-olds whose blood contained relatively high levels of PFCs.

“We found that the higher the exposure, the less capable the kids were in terms of responding appropriately to the vaccine,” Grandjean says. The results raise the possibility that “the immune system is not really developing optimally.”