Adverse events following immunisation (AEFI) reports from the Zimbabwe expanded programme on immunisation (ZEPI): an analysis of spontaneous reports in Vigibase from 1997 to 2017
More than one in ten vaccine-related adverse events in Zimbabwe are serious (11%), and measles-containing vaccines are one of the vaccines most frequently responsible for serious and systemic reactions.
The authors examined passively collected reports of adverse events following immunization (AEFI) in Zimbabwe from 1997 to 2017. Given widespread underreporting to the country’s still-developing vaccine surveillance system, just 272 Individual Case Safety Reports (ICSRs) were available, of which 11% represented “serious events.” Of these, 6% were deaths and 5% were life-threatening or involved prolonged hospitalization. Measles-containing vaccines had the highest AEFI reporting rate and were also strongly associated with serious events, as was a six-component vaccine containing antigens for oral poliovirus, diphtheria, tetanus, pertussis, Haemophilus influenzae type b and hepatitis B (OPV/DTP-Hib-HepB). The majority of AEFI were systemic (versus vaccine site reactions)—and systemic events, again, were associated with measles-containing vaccines.
One dose of diphtheria, tetanus, and pertussis vaccine was associated with a mortality ratio of 1.84 (1.10 to 3.10) and two to three doses with a ratio of 1.38 (0.73 to 2.61) compared with children who had received no dose of these vaccines.”
Kristensen I, Aaby P, Jensen H. British Medical Journal. 2000 Dec 9;321(7274):1435-8.
Research on vaccines in developing countries recommended by the World Health Organization has emphasised serological responses and protection against specific diseases. The aim of the research has been to optimise vaccine schedules for control, elimination, or eradication of disease. In modelling exercises, vaccination against diphtheria, pertussis, tetanus, and polio has been assumed to save 1.52.0% of the children in areas with high infant mortality. However, these assumptions are not supported by data. Mortality was lower in the group vaccinated with any vaccine compared with those not vaccinated, however, recipients of one dose of diphtheria, tetanus, and pertussis or polio vaccines had higher mortality than children who had received none of these vaccines.