Incidence of adverse reactions to vaccines in a paediatric population.

Objective: To detect the appearance and specify the types of adverse reactions to vaccines registered in a paediatric population.

Patients And Methods: A 6-month, prospective, observational, multicentre epidemiological vaccine safety study was undertaken in 2002 covering a paediatric population subject to vaccine administration. A two-phase telephone survey of all patients was conducted, comprising an initial call at 1 week and a follow-up call at 30 days after the vaccine administration date. A paediatrician was responsible for diagnosing the specific type of adverse reaction.

Results: Of a total sample of 946 children, ranging in age from 0 to 14 years (50.8% girls, 49.1% boys), 191 non-serious suspected adverse reactions were detected, representing 19% of the vaccinated children. Reactions to the diphtheria, tetanus, pertussis acellular and Haemophilus influenzae type b (DTPa + Hib) vaccine appeared in 43.4% of cases, followed by reactions to the measles, mumps, rubella (MMR) [18.4%] and adult tetanus and diphtheria (Td) [17.8%] vaccines. The most frequent types of adverse reactions to vaccines were: injection-site oedema (12.2 per 1000 doses); pain at site of inoculation (10.3 per 1000 doses); temperature not recorded but believed by parents to be very high (4.6 per 1000 doses); and measured temperature indicating fever of 39-40.5 masculineC (4.4 per 1000 doses). Fifty-five percent (n = 21) of cases of injection-site oedema were attributed to DTPa + Hib vaccine (18.8 per 1000 doses), followed by 18.4% (n = 7) attributable to Td vaccine (112 per 1000 doses). Indeed, this latter vaccine was responsible for 43.8% (n = 14; 226 per 1000 doses) of all reported pain at the site of inoculation. MMR vaccine was linked to the occurrence of fever of 39-40.5 masculineC in 52% of cases (n = 10; 29 per 1000 doses). Two children were treated by the emergency services, but there were no deaths or hospitalisations.

Conclusions: An active search for subjects with suspected adverse reactions to vaccines led to the detection of reactions that are usually not reported. Primary-care physicians and nurses must be vigilant for information on adverse reactions to vaccines in paediatric populations.