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A whooping cough booster vaccine recommended for middle school aged children loses effectiveness over time, a new study is reporting.

Whooping cough is a highly contagious respiratory infection that has symptoms that include a cough that sounds like a "whoop," runny nose, sneezing and nasal congestion. The infection can be very dangerous for infants.

For this study, the researchers from Kaiser Permanente examined how well the Tdap booster protected adolescents from whooping cough, also known as pertussis. The Tdap booster also protects the body against tetanus and diphtheria. The team analyzed diagnosed cases in nearly 280,000 children from 2009 to 2015. Almost all of the children had gotten the Tdap booster when they were 11 to 12.

The researchers found that within the first year after immunization, the booster vaccine's protection rate was around 69 percent in 11 to 12-year-old children. In the second year, the protection rate dropped to 57 percent. Four years later, however, only about nine percent of this group of children was still sufficiently protected from whooping cough.

"It provides moderate protection during the first year but years two and three after vaccination, there is not that much protection left," lead study investigator, Dr. Nicola P. Klein, co-director of the Kaiser Permanente Vaccine Study Center in Northern California, said reported by CNN.

The findings help explain why the number of whooping cough cases within the U.S. has been increasing. The U.S. Centers for Disease Control and Prevention (CDC) reported that in 2012, there were 48,277 confirmed cases and 20 deaths, which is the highest since 1955.

The CDC currently recommends children to receive five does of the whooping cough vaccine, DTaP between the ages of two months and four to six-years-old. By age 11 to 12, children are recommended to get the booster. Another booster vaccine is also recommended for adults between the ages of 19 and 64, and in pregnant women.

"I think we need to open the discussion on how to best utilize the vaccine," Klein said.

The study's findings were published in the journal, Pediatrics.