Incidence of adverse reactions to vaccines in a paediatric population

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

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.

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.

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.