Best Booster Schedules for Combating Whooping Cough

By simulating pertussis resurgences, researchers have identified the immunization schedules that result in the greatest reduction in whooping cough at the lowest economic cost.

For their study published in the January 19, 2015, edition of the Proceedings of the National Academy of Sciences, the investigators examined the root causes behind the resurgence of whooping cough in countries that have integrated pertussis booster shots into childhood immunization schedules, including the United States.

In doing so, the researchers identified insufficient vaccine coverage, low vaccine efficacy, waning immunity, and “leaky” vaccines as potentials mechanisms for the resurgence. The study authors explained that a vaccine is leaky when it does not include all microbial strains circulating in the general population, similar to this year's influenza vaccine.

When low vaccine coverage and efficacy were the culprits behind simulated pertussis resurgences, the most effective immunization strategy was a single vaccine before children enter kindergarten, the study authors found. When waning immunity was the primary cause, the most successful schedules involved a series of boosters administered between ages 5 and 45 years. However, the researchers’ model found no immunization schedules that reduced the incidence of pertussis when leaky immunity caused the disease’s resurgence.

"If a vaccine is too leaky, the pathogen can continue to circulate in a fully vaccinated population, and you won't be able to get elimination using that vaccine alone," said first study author Maria Riolo in a press release. "You can still get a large reduction from pre-vaccine levels of disease, but the leakiness limits how far you can get."