Pertussis vaccine guidelines expand as disease spreads
■ A federal advisory panel says Americans 11 to 64 years old need a dose if they have not yet received one.
To help slow the spread of pertussis across the country, a federal vaccine advisory committee has broadened recommendations for the Tdap immunization to ensure that Americans have sufficient immunity against the disease.
Americans 11 to 64 years old need one dose of the Tdap vaccine as soon as feasible if they have not yet received it, according to the Advisory Committee on Immunization Practices. One dose should be administered to patients in this age group if their vaccine history is unknown, the ACIP said at an Oct. 27 meeting in Atlanta. The 15-member committee advises the Centers for Disease Control and Prevention on vaccine issues.
The new guidelines also eliminate intervals between receipt of the tetanus-diphtheria (Td) vaccine and the Tdap (tetanus-diphtheria-acellular pertussis) immunization. Previous ACIP guidance encouraged physicians to wait at least five years between Td and Tdap shots. Such intervals kept many patients who needed the booster from receiving it, said Jennifer Liang, a medical epidemiologist in the CDC's Division of Bacterial Diseases.
As of 2008, only 5.9% of adults 18 to 64 had received a Tdap shot in the past 10 years, according to the most recent CDC data.
Neither of the two Tdap vaccines approved for use in the U.S. is licensed for children 7 to 10 or adults 65 and older. But the ACIP said research shows that the vaccines are safe for patients in these age groups and would help reduce transmission of pertussis to infants.
Liang said grandparents pass the disease to an infant in 6% to 8% of cases. Siblings are the source of pertussis in 16% to 20% of incidents.
"The burden of disease in people 65 and older is under-recognized, but they're potential sources of transmission to infants," Liang said.
GlaxoSmithKline is pursuing licensure in the 65-and-older population for its Tdap vaccine Boostrix, which is approved for use in individuals 10 to 64. Sanofi Pasteur is working with the Food and Drug Administration to license its Tdap vaccine, Adacel, for people 65 and older. The immunization is authorized for use in Americans 11 to 64.
The two manufacturers said they have not studied their vaccine's effectiveness in children 7 to 10 and are not pursuing licensure for that group.
Outbreaks added a sense of urgency
The ACIP recommendations were issued as pertussis continues to spread nationwide. In California, more than 6,200 cases and 10 pertussis-related deaths -- all in infants -- have been reported as of Oct. 26, said Kathleen Harriman, PhD, MPH, of the Immunization Branch of the California Dept. of Public Health.
Although California has the highest number of reported cases, pertussis is on the rise in other states, including Minnesota, Ohio and South Carolina, said Thomas Clark, MD, MPH, a medical epidemiologist in the CDC's Meningitis and Vaccine Preventable Diseases Branch.
The outbreak "added a sense of urgency [to developing the recommendations] and helped the [ACIP] working group really understand the implication, at the individual level, to removing barriers to pertussis vaccination," Dr. Clark said.
During its meeting, the ACIP recommended that adolescents receive a second dose of the meningococcal vaccine at age 16 due to waning immunity of the immunization over time. The CDC advises that the first dose be administered to patients between ages 11 and 18.