What is Pertussis?
Also known as whooping cough, pertussis is a highly contagious disease. It is also the most common vaccine-preventable disease in the U.S. Pertussis can cause serious and sometimes life-threatening complications in infants and young children, especially those who are not fully vaccinated.
The disease begins as a mild respiratory infection with symptoms such as coughing, sneezing, and runny nose. After one to two weeks, the cough increases and develops a "whooping" sound. Above is a video showing a child during a pertussis coughing episode. (Notice how the cough is continuous and the child has difficulty catching it's breath.)
In severe cases, vomiting induced by the coughing fits can lead to malnutrition and dehydration. Pneumonia, encephalitis, pulmonary hypertension and secondary bacterial super infections are among the many side effects that pertussis victims may face.
In adults, the disease often seems like a bad cold with mild symptoms. Since most adults won't recognize that they have pertussis, it is not unusual for them to spread the disease to vulnerable children. In approximately 85% of infant pertussis cases, babies are infected by a member of their immediate or extended family. Most unvaccinated children living with a family member with pertussis will contract the disease.
The Centers for Disease Control and Prevention (CDC) reported that the introduction of the pertussis vaccine in the mid-1940s decreased pertussis incidence to only 1,010 cases by 1976, an all-time low. However, pertussis is a cyclical disease with a higher number of cases in certain years. Ninety-percent of pertussis-associated deaths have been among babies less than one year old. More than half of infants younger than 1 year of age who contract the disease must be hospitalized. About 1 in 5 infants with pertussis develop pneumonia, and approximately 1 in 100 will experience convulsions. In some cases (1 in 100), pertussis can be deadly, especially in infants.
Research published in the Journal of the American Medical Association (JAMA) Pediatrics in September 2013 showed that undervaccination is associated with a higher risk of pertussis in children. The investigators of the case-control study of children ages 3 to 36 months found that those who missed three doses of the DTaP vaccine were nearly 19 times more likely to develop pertussis than those appropriately vaccinated, and those who missed four doses were 28 times more likely to develop the disease.
Large outbreaks of pertussis have been occurring in the U.S. in recent years. In 2010, more than 27,000 cases were reported and by 2012 that number rose to more than 48,000 cases, marking a 58-year high. There were almost 33,000 cases in 2014; approximately 18,000 cases in 2015; and outbreaks have continued in 2016.
There are several reasons that help explain why there have been more cases of pertussis over the last few years including increased awareness, improved diagnostic tests, better reporting, more circulation of the bacteria, and waning immunity. Pertussis vaccines are effective, but not perfect. They typically offer high levels of protection within the first 2 years of getting vaccinated, but then protection wanes over time. In addition, many children fail to receive all of the required doses and remain vulnerable.
There are two vaccines used to protect against pertussis, Children need to receive all 5 doses of DTaP, a combined tetanus, diphtheria and pertussis vaccine, to be protected. One dose is needed at 2 months, 4 months, and 6 months, between 15-18 months and between 4-6 years. Preteens should receive one dose of Tdap at 11 or 12 years old. Adults 19 years of age and older who didn't get Tdap as a preteen or teen should also get one dose of Tdap.
Adults can help to protect themselves and the young children around them by getting immunized with the adult pertussis vaccine (Tdap).
Pregnant women should be vaccinated with Tdap during each pregnancy (preferably in the third trimester between the 27th and 36th weeks of pregnancy). By getting vaccinated during pregnancy, mothers build antibodies that are transferred to the newborn providing protection against pertussis before the baby can start getting DTaP vaccine at 2 months old. Tdap also protects mothers during delivery, which makes them less likely to transmit pertussis to their infants. This recommendation is supported by The American College of Obstetricians and Gynecologists and The American College of Nurse-Midwives.
Parents should proactively request that all those who will be in contact with their newborn, including healthcare workers, get a Tdap vaccine at least two weeks prior to delivery to help protect their infant until they are fully vaccinated.