Recent outbreaks of pertussis in various states demonstrate a resurgence of this disease in an immunized population. Although there is high pertussis vaccine coverage for children nationwide, protection from childhood vaccines appears to wane over time. Pertussis can be serious, especially in infants.
The CDC Advisory Committee on Immunization Practices (ACIP) has recently revised recommendations for use of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine (Boostrix—GlaxoSmithKline; Adacel—Sanofi Pasteur) so that those individuals who are most vulnerable will be protected.
CDC reported more than 2,520 pertussis outbreaks throughout Washington State so far this year (January to mid-June), compared with 179 cases reported last year during the same period. The median age for outbreaks is 10 years. A total of 965 cases were reported in the state in 2011; 608 total cases were reported in 2010.
Washington State isn’t the only area to see an increase. In 2010, 9,143 cases of pertussis were reported throughout California, the highest number of pertussis cases in more than 6 decades. Nationwide, a total of 27,550 cases were reported in 2010 and a total of 15,216 cases were reported in 2011. Thus far in 2012, more than 13,000 cases have been reported in the United States.
Revised ACIP recommendations
ACIP recently revised its recommendations for use of the Tdap vaccine in pregnant women and others who are in close contact with an infant younger than 12 months. For pregnant women who have not received the Tdap vaccine, ACIP now recommends that these women receive the vaccine after 20 weeks gestation, during the third or late second trimester. If the vaccine is not administered during pregnancy, then it should be given immediately postpartum.
ACIP reviewed published and unpublished data from the Vaccine Adverse Event Reporting System, pregnancy registries for the two Tdap products, and data from small studies. Overall, an analysis of these data did not reveal any elevated frequency or unusual patterns of adverse events in pregnant women.
The group noted that from a safety perspective, administration of the Tdap vaccine after 20 weeks gestation was an attempt to minimize the risk for any low-frequency adverse events and reduce the possibility that any spurious association may appear causative.
ACIP also noted that administration of the Tdap vaccine to pregnant mothers may result in tranplacentally transferred maternal antibodies that may provide protection in the infant early in life (0–2 mo). It is estimated that the half-life of maternal pertussis antibodies is approximately 6 weeks, although the effectiveness of these antibodies in preventing pertussis in the infant is currently unknown.
ACIP recommended that any people in close contact with infants younger than 12 months, such as the father, adolescent siblings, grandparents, and childcare personnel, should receive a single dose of Tdap to protect against pertussis if they have not previously received the vaccine. This strategy is known as cocooning. It is recommended that this group of individuals receive the Tdap vaccine at least 2 weeks prior to having close contact with the infant.
New parents and others who care for an infant should be educated about the importance of receiving the Tdap vaccine to aid in the prevention of pertussis. They should understand that the disease is extremely contagious and is usually spread by coughing or sneezing while in close contact with others. Most infants get the disease from infected parents, older siblings, or other caregivers. Explain to patients that although the vaccine is not 100% effective in preventing pertussis, it is the best option for preventing the spread of the disease.
If parents notice that their child has a cold that develops into a prolonged or severe cough, then they should seek medical care to determine if the child has pertussis. Pertussis is often described as a series of coughing fits that continues for weeks, with some patients having violent and rapid coughing over and over again until they are forced to inhale with a loud whooping sound. Some patients, particularly infants, however, may not have such severe symptoms and may only present with a mild cough.
At the June ACIP meeting, additional recommendations for revaccination for pertussis were discussed and the group’s findings will be reported at a future meeting. ACIP noted that one challenge in Washington State is difficulty in obtaining the Tdap vaccine for Medicare Part D patients. This opens the door to a potential role for pharmacists to help this patient population obtain Tdap vaccinations.