The United States is on track to have the most cases of whooping cough in 5 decades--and waning vaccine effectiveness may be to blame.
The United States is on track to have the most cases of whooping cough in 5 decades—and waning vaccine effectiveness may be to blame.
Public health officials predict that there will be more cases of whooping cough in the United States this year than at any time since the late 1950s and suggest that waning effectiveness of the vaccine that protects against it may be responsible. According to the Centers for Disease Control and Prevention (CDC), there had been almost 18,000 cases of whooping cough (also known as pertussis) reported as of July 19, 2012, more than twice the number at the same point in 2011. At this rate, the number of cases for the entire year is on track to be the greatest since 1959, when 40,000 cases were reported.
Recommendations call for children to receive 5 doses of the DTaP vaccine, which protects against diphtheria, tetanus, and pertussis, starting at 2 months and ending at 4 to 6 years. A booster shot is also recommended at age 11 or 12. Since 1997, when a whole-cell version of the pertussis vaccine was phased out due to unproven concerns over a potential link to neurological problems and adverse reactions, all pertussis vaccine has been the acellular version.
This year, the highest rates of whooping cough have been among infants under a year old, with half of cases in infants younger than 3 months who have not yet received their first dose of the vaccine. However, there have also been high rates of infection among 10-year-olds and those aged 13 and 14 despite high rates of vaccination among these groups. These data, along with increasing rates among children aged 7 to 10 years, suggest that the protection afforded by the vaccine fades with time. Notably, all children in these age groups have received only the acellular version of the pertussis vaccine.
Nonetheless, the CDC notes that vaccination remains the best means of preventing further spread of whooping cough and urges all adults, particularly pregnant women and others who have regular contact with children, to get a booster shot. In a letter dated June 26, 2012, the CDC called on pharmacists and other community vaccinators to increase awareness among patients of the vaccinations they need.
Whooping cough, which is treated with antibiotics, generally begins with cold symptoms, which can include a runny nose, congestion, fever, and cough. As it develops, patients develop severe, uncontrollable coughing causing difficulty breathing and, frequently, a “whooping” sound when breathing is attempted. Parents should be advised to take children to a doctor if they have prolonged or severe cough. This year, whooping cough has been particularly common in Washington State, as well as Wisconsin, New York, Minnesota, and Arizona. Washington, which declared an epidemic on April 3, 2012, had 2250 pertussis cases by June 16, 2012, a 1300% increase over the same period in 2011. Nationwide rates of whooping cough have been on the rise since the early 1990s, reaching more than 25,000 cases in 2004 and 2005, and 27,000 in 2010.
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