Help protect your grandchildren. Pertussis is on the rise since hitting an all time low in 1976. The Tdap vaccine is recommended for anyone who spends time with children younger than 12 months. Whooping cough is dangerous for very young children and it is most contagious before the symptoms appear. Even if you had the vaccine many years ago, talk to your physician about risks and benefits and make sure you are up to date on all your vaccinations.