Washington’s whooping cough epidemic passed 3,000 reported cases this week while new study from the Centers for Disease Control and Prevention (CDC) indicates vaccine protection doesn’t last as long as expected, according to a Washington Department of Health (DOH) press release.
The fact that the protection wears off sooner than was previously thought is among the reasons that most cases in Washington are in school age children who are vaccinated. An upcoming study in Washington by health investigators will look into similar information for the Tdap booster vaccine for teens and adults.
“Whooping cough vaccines work but don’t seem to last as long as was expected,” said Secretary of Health Mary Selecky. “Even so, vaccinated people who get whooping cough have milder symptoms, shorter illnesses, and are less likely to spread the disease to others. Our biggest concern is keeping babies from getting sick – and vaccination is still the best protection.”
A report on the Washington epidemic was published today in the CDC’s weekly publication. The report highlights more reported cases among 13-14 year olds – a changing trend across the country that indicates a shorter duration for vaccine protection against whooping cough (pertussis).
Whooping cough is respiratory bacterial disease causes uncontrollable fits of coughing and can be deadly to infants and small children. King County officials warn that the disease is a highly contagious disease that it is not confined to a single location, and that confirmed cases do not paint a complete picture of how widespread the epidemic is. Eight babies have died of pertussis in the U.S. so far this year, but none in the state.
"The cases that are reported to us are the tip of the iceberg," said Public Health Seattle & King County spokesperson James Apa. "People who have pertussis likely don't see a doctor — it may be a nagging cough for them. The numbers that we have represent just a fraction of what we believe we actually have."
Pierce County health officials similarly are seeing very high rates of pertussis that have not been seen in decades, according to spokesperson Nigel Turner in an email communication to local media Thursday. "So far in 2012, 446 cases have been reported in Pierce County as of July 14," he reported.
Consistent with trends being reported for Washington state, Pierce County is also seeing a larger proportion of cases in older school-aged children, he said.
The focus on Washington state comes as a statewide epidemic continues and has reached annual levels not seen since 1941, when there were approximately 200,000 confirmed cases nationwide (4,960 cases in Washington state). According to the CDC, about 25,000 cases in the U.S. were confirmed in 2010 — a 50-year high — and 2012 is on pace to exceed that.
Whooping cough continues to be a very serious threat to infants who are at greatest risk of serious disease if they’re infected; they’re often hospitalized. Babies get the first dose of whooping cough vaccine at two months of age and need a series of five shots to be fully protected. So far this year 185 cases have been reported in children less than one year old; 39 have been hospitalized.
“We’ve been working hard to slow the spread of disease and understand better what’s going on,” said Secretary Selecky. “CDC has been a huge help. Analyzing the details of the whooping cough epidemic in Washington could help CDC and other states learn some things that weren’t known before, and see this changing trend – and that’s public health in action.”
CDC is helping Washington’s disease investigators analyze data as part of an “epi-aid” to the state; they have also helped with outreach. DOH will continue to work with CDC on a study of how long the Tdap vaccine lasts and how well it protects people.
Information from a study done during the 2010 California whooping cough outbreak showed that the DTaP vaccine for children works very well for the first couple years after vaccination. The data from California also showed that the protection decreases to about 70 percent effectiveness five years after vaccination. That means kids are more at risk for getting the disease the longer it’s been since they were vaccinated. DOH officials say they will investigate similar concerns in its upcoming study.
“The more we learn about whooping cough, the better we’ll be able to fight this epidemic,” said State Health Officer Dr. Maxine Hayes. “It’s a miracle a baby hasn’t died in our state yet this year – it has happened before and could happen again. Although vaccine protection wears off over time, vaccination remains the best tool we have to slow the spread of this serious disease. That’s why we’re asking everyone to get vaccinated.”
Dr. Hayes adds that vaccination can reduce the severity of symptoms, shorten the illness, and make it less likely to be spread to others.
More information on the whooping cough vaccines, including where to get vaccinated, can be found at the State Department of Health website's frequently asked questions. The CDC article on the Washington whooping cough epidemic is available online. The Department of Health website is also on Facebook and Twitter.
(Ed. Note: The information in this article was provided by the State Department of Health)