Modeling rates of infection with transient maternal antibodies and waning active immunity: application to Bordetella pertussis in Sweden.

Serological surveys provide reliable information from which to calculate forces (instantaneous rates) of infection, but waning immunity and clinical consequences that depend on residual immunity complicate interpretation of results. We devised a means of calculating these rates that accounts for passively acquired maternal antibodies that decay or active immunity that wanes, permitting re-infection. We applied our method to pertussis (whooping cough) in Sweden, where vaccination was discontinued from 1979 to 1995.

Long-term follow-up of Swedish children vaccinated with acellular pertussis vaccines at 3, 5, and 12 months of age indicates the need for a booster dose at 5 to 7 years of age.

Objectives: The purpose of this work was to evaluate the long-term effectiveness of vaccination with acellular pertussis vaccines at 3, 5, and 12 months of age.

Methods: Clinical follow-up of reported culture- and polymerase chain reaction-confirmed cases of pertussis was initiated during October 1997 in most of Sweden (except Gothenburg and environs). The study population included 90% of Swedish children born during 1996 or later (ie, who received diphtheria-tetanus-acellular pertussis vaccines at 3, 5, and 12 months of age) and children who had participated in a large pertussis vaccine trial in 1993-1996.

Vaccinovigilance in Europe--need for timeliness, standardization and resources.

Objective: To identify gaps in the systems for reporting adverse events following immunization (AEFI) in Europe by means of an interactive database constructed using a standardized approach.

Methods: A comparative survey was conducted in 1999-2000, using structured questionnaires addressed to the government authorities responsible for national immunization programmes and drug safety surveillance in all European Union (EU) Member States and in Norway and Switzerland.

Findings: The reporting of adverse vaccine reactions (AVRs) is covered by regulations in 13 of the 17 countries.

Low levels of antipertussis antibodies plus lack of history of pertussis correlate with susceptibility after household exposure to Bordetella pertussis.

Prospectively collected data in a Swedish vaccine efficacy trial were used to investigate transmission of pertussis from small study infants to other household members. Forty one percent (258/627) of the exposed persons with paired serology had laboratory confirmed pertussis. The majority of those with laboratory confirmed pertussis had less than 14 days of cough and many were asymptomatic.

Declining pertussis incidence in Sweden following the introduction of acellular pertussis vaccine.

Acellular pertussis vaccines were introduced nation-wide in Sweden in 1996, 17 years after the withdrawal of whole-cell pertussis vaccine from the childhood immunisation schedule. We report national data on age specific incidence of culture-confirmed Bordetella pertussis for 1986-2000, and clinical follow-up for 3 years (October 1997-September 2000) in children born in 1996-2000 and from children born in 1993-1994 who had participated in a trial of pertussis vaccines. The annual incidence of culture-confirmed B.