A California city with a large number of whooping cough cases despite a high immunization rate is revealing the limitations of the current vaccine used to protect against the disease.
The Sacramento Bee reports that Elk Grove had a whooping cough infection rate three to five times higher than other places in Sacramento County last year even though only 80 of the suburb's 4,500 kindergartners opted out of vaccinations.
Experts say the whooping cough vaccine introduced in the late 1990s provides less protection each year after it is administered, often leaving children vulnerable before they get their booster shot.
Concerns about the vaccine come as a record-high 11,000 Californians caught whooping cough in 2014.
Still, experts say parents should vaccinate their children against whooping cough because the vaccine reduces the chances of infection.