Health care workers may need a new vaccine to fight pertussis

Hospital outbreaks affect HCWs, newborns

Another vaccine is on the horizon for health care workers — this time to protect them and their patients from a troubling resurgence of pertussis, the "whooping cough" illness that is particularly dangerous for young infants.

Hospital outbreaks have been reported in Kentucky, Pennsylvania, and Oregon, affecting health care workers and infants.1 Within the year, the Food and Drug Administration is expected to approve two new pertussis vaccines, one for adolescents and one for adolescents and adults. The booster vaccine contains three antigens of pertussis and would be combined with diphtheria and tetanus boosters.

Pertussis cases have been rising around the country, spread by adolescents and adults with waning immunity.

"Here in our own community [of Rochester, MN], we’ve documented well over 100 cases this year," says vaccine expert Greg Poland, MD, director of the Mayo Vaccine Research Group at the Mayo Medical School of the Mayo Clinic and Foundation. "We haven’t had this many documented cases in decades."

In fact, Poland’s 13-year-old son developed pertussis, as did many other students at his middle school. Three months after his first symptoms and treatment, he’s still coughing, says Poland, who is a member of the Advisory Committee on Immunization Practices (ACIP), the federal panel that will issue recommendations on the vaccine.

"The cough is related to the toxin," he notes. "When you take the treatment, all you’re doing is killing the bacteria. The bacteria already released the toxins, [and] there’s no treatment for that."

At Vanderbilt University Medical Center in Nashville, TN, the number of hospital-based exposures to pertussis rose significantly in the past two years. In 2001-2002, only one case occurred. In 2002-2003 and 2003-2004, there were nine and 11 cases, respectively, says Melanie Swift, MD, medical director of Vanderbilt Occupational Health Clinic.

Last year, those exposures led the hospital to evaluate 128 health care workers, offer them prophylactic antibiotics, and monitor them for symptoms, she explains. The preferred prophylactic treatment is a high dose of erythromycin four times a day for two weeks, Swift notes.

"That [booster vaccine] would be an easy thing to incorporate," she adds. "I can see significant benefit from doing that if it’s going to protect these workers from what appears to be a growing number of recognized cases of pertussis."

The rise in pertussis affects communities throughout the country. The reported cases increased from 11,647 in 2003 to more than 18,000 in 2004, Trudy Murphy, MD, a medical epidemiologist with the National Immunization Program, told the ACIP advisory panel.

Some examples: Massachusetts, which closely monitors pertussis through serology testing, recorded 49 outbreaks in 2003. Fond du Lac, WI, reported more than 2,000 adolescent cases in 2004, including 111 hospitalizations. A high school in Pike County, AR, canceled homecoming when about a third of the student population became infected with pertussis.

Outbreaks in pediatric or neonatal facilities would be of particular concern. Infants 2 months and younger cannot be vaccinated against pertussis. "Very young infants make up the vast majority of deaths," Murphy said.

Delays in diagnosis raise the risk of transmission, CDC cautioned in a January 2005 report in the Mortality and Morbidity Weekly Report. In a Kentucky case, for example, four nurses cared for a 2-month-old child who had been born prematurely and was in the intermediate care nursery. At least three of them had symptoms of pertussis-like illness while caring for the infant, who developed pertussis. The infant was transferred to the neonatal intensive care unit, placed on a ventilator, and given antibiotics. The child survived.1

Later testing indicated that three of the nurses had antibodies indicative of pertussis infection. Meanwhile, a physician who treated the infant and was in her first trimester of pregnancy developed pertussis. Antibiotic prophylaxis was given to 72 other patients and 72 health care workers, and no one else became infected.

Because adolescents often spread the disease to family members, including infants, they are the first target of the new booster vaccine, explains Michael Decker, MD, MPH, vice president for Scientific and Medical Affairs at sanofi-aventis in Swiftwater, PA, and Paris.

Adults — and particularly health care workers — will follow soon after, he says. "I would be surprised if there weren’t some states that mandated it [for health care workers]," says Decker, a former hospital epidemiologist. "With [the vaccine], we’re protecting not only our workers but also our patients."

Employee health professionals can incorporate the vaccine as a substitute for the current tetanus booster, Swift notes. The question about the pertussis vaccine "is not so much if it’s a good idea, but if it would be mandatory," she says.

The pertussis booster currently is being used in about 42 countries with few side effects and no serious adverse events, Decker says.

Reference

1. Centers for Disease Control and Prevention. Outbreaks of pertussis associated with hospitals — Kentucky, Pennsylvania, and Oregon, 2003. MMWR 2005; 54:67-71.