Pri-Med Southwest: Update on Pertussis

Session at Pri-Med Southwest focuses on the current epidemiology of pertussis and updated vaccine recommendations.

The Clinical Problem Solving in Pediatric & Adolescent Medicine session Friday at the 2011 Pri-Med Southwest conference included an update on pertussis by Flor Muñoz-Rivas, MD, a pediatric infectious disease consultant at Texas Children’s Hospital in Houston, Texas. During her presentation, Muñoz-Rivas reviewed the current epidemiology of pertussis and reviewed newly updated vaccine recommendations.

In 2010, there were over 21,000 reported cases of pertussis in the United States. The actual number is probably higher because pertussis is frequently misdiagnosed. Although young children are routinely vaccinated for pertussis, immunity is not long-lasting. Children become susceptible to disease at around 10-11 years of age.

ACIP Vaccination Recommendations

Immunization is considered the key intervention for pertussis control. New acellular pertussis vaccines that contain purified pertussis components are less reactive than the older whole-cell formulations. Due to prevailing pertussis susceptibility in the population, the Advisory Committee on Immunization Practices (ACIP) recommends vaccination with tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) for adolescents and adults to improve immunity against pertussis. Two Tdap vaccines are available in the US.

ACIP recommends:

• A single Tdap dose for persons aged 11 through18 years who have completed the recommended child¬hood diphtheria and tetanus toxoids and pertussis/diphtheria and tetanus toxoids and acellular pertussis (DTP/DTaP) vaccination series
• A single Tdap dose for adults aged 19 through 64 years

2010 ACIP Updates

A 2010 outbreak of pertussis in California prompted ACIP to re-examination and update vaccination recommendations for the disease.

Use Tdap regardless of interval since the last tetanus- or diphtheria-toxoid containing vaccine

The current dogma is that the perceived benefits outweigh the risks. There is a good amount of evidence demonstrating that Tdap given after Td or DtaP is well-tolerated at intervals of 1-18 months.

Use Tdap in certain adults aged 65 years and older

Over the last decade, there were nearly 3,000 reported cases of pertussis in the U.S. among adults 65 years of age or older. Adults aged 65 years or older who may be in close contact with an infant less than 12 months of age should receive a single dose of Tdap.

Use Tdap in undervaccinated children aged 7 through 10 years

There is no Tdap vaccine licensed for use in children less than 10 years of age. Children with an incomplete or unknown pertussis vaccination history should receive a single dose of Tdap. In four studies of Tdap for the fifth dose of immunization series, there were no severe local or systemic adverse events in fully vaccinated children. A similar profile is expected in undervaccinated children. Tdap is licensed in Canada starting at four years of age.

Treatment

The persistent, dry cough that is characteristic of pertussis does not start until the second or third week of illness. Despite this, treatment with a macrolide antibiotic should be initiated to reduce transmission and limit severity of disease. Supportive care should also be provided. For safety reasons, azithromycin is the preferred treatment. Antibiotics should also be given to close contacts of cases to prevent disease. Because pertussis is a toxin-mediated disease, toxin may remain after bacteria have been eliminated, resulting in lingering inflammatory effect.

What else can be done?

• Improve adolescent and adult vaccine coverage; only about 2/3 of teens are covered. Hopefully, school vaccination requirements will increase coverage
• Improve on-time vaccinations of infants less than six months of age
• Initiate targeted immunization. For example, target postpartum women or people who will be around children