Anyone in close contact with an infant – even those over the age of 65 – should get the vaccine for pertussis (whooping cough), health officials advise.

The new recommendation from the American Academy of Pediatrics and the U.S. Centers for Disease Control and Prevention is the result of a nationwide surge in whooping cough infections in 2010.

“Not only is there pertussis or whooping cough, but we are entering the influenza and respiratory syncytial virus seasons,” said Dr. Eric Scott Palmer, a Nashville neonatalist. “[They] can and do kill infants, particularly former premature infants.”

Many adults assume that once they’ve had whooping cough, they’re immune, or don’t realize they carry the virus, said Dr. Kelly Moore, an immunization program director in Tennessee. Even those who have had the vaccine require a booster shot every 10 years or so.

“What is frightening is that people with an ordinary cough illness might not think they have pertussis and might expose a newborn or infant unknowingly,” Dr. Moore said.

California had the worst outbreak of whooping cough in 63 years: over 9,000 cases were confirmed in 2010. Michigan and Ohio also had high rates of pertussis infections in 2010. The actual rate of occurrence may be higher, as many cases are never diagnosed or confirmed, Dr. Moore added.