SAN FRANCISCO — Preliminary results from a European study suggest that the appropriate time for pertussis booster administration after school age may differ according to local factors such as circulation of the disease, the type of vaccine, and the vaccine schedule in use, Dr. Alberto Tozzi reported during a poster session at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy sponsored by the American Society for Microbiology.
“Now that the United States has recommended a booster dose in adolescents, every country in Europe will try to follow the same recommendation,” Dr. Tozzi of Bambino Gesù Hospital in Rome said in an interview. “This, to me, is not appropriate, because there are different patterns and scenarios that need to be accurately investigated.”
He and his associates used the pertussis screening method in 16 European countries and World Health Organization data to calculate vaccine efficacy by age and vaccination cohort between 1998 and 2002. The countries included in the study were Austria, Denmark, France, Germany, Greece, Iceland, Ireland, Italy, Malta, Norway, Portugal, Spain, Sweden, Switzerland, the Netherlands, and the United Kingdom.
The researchers found that the pertussis vaccine efficacy exceeded 80% in each of the countries except Sweden and Norway. The immunization schedules in those Scandinavian countries, he said, do not include administration of a booster dose at school age. As a result, “they experience a big increase of cases after that age, because immunity induced by the immunization does not last that long,” Dr. Tozzi said.
On the other hand, in Italy and France, where the vaccination schedule includes a booster dose at school age, the efficacy against pertussis was sustained until adolescence.
The type of vaccine matters, too. In the Netherlands, for example, clinicians currently use the cellular form of the pertussis vaccine. As a result, Dr. Tozzi noted, efficacy is maintained only for a few years.
“Looking at all this data, you must take into account the background coverage for pertussis, the type of vaccine used, and the schedule,” he said. “All of these things must be looked at before deciding which kind of booster dose is to be given” and when.
He and his associates are collecting more data from these 16 countries in an effort to correctly plan the appropriate time to administer a booster dose of vaccine. The study is part of the Euvac.net project, an ongoing effort to monitor and control vaccine-preventable diseases in Europe, funded by the European Parliament and Council.
'You must take into account the background coverage for pertussis, the type of vaccine used, and the schedule.' DR. TOZZI