RESUMEN
OBJECTIVE: To compare the local and systemic reactogenicity of two vaccine associations in infants, in order to ascertain if a greater volume of injection is associated with a greater adverse effects rate. DESIGN: Intervention study, without random distribution. Site. A unit of vaccinations with free access and public dependency. PARTICIPANTS: 228 infants (138 male, 90 female) aged 2, 4 and 6 months that were attending to compliment their vaccine schedule. INTERVENTIONS: To those aged 2 and 6 months (group 1: 108 children) it was administered the association DTPw + Hepatitis B + Hib (Tritanrix-HB + Hiberix) with a volume of injection of 0,5 ml, and to those aged 4 months (group 2: 120 children) the association DTPw + Hib (Anatoxal Diteper + Hibtiter) with a volume of 1 ml. The injection was applied in the thigh and paracetamol was indicated in the following 24 hours. Adverse reactions were registered through telephonic interview, and nursing visit of those which might have presented some one. RESULTS: There were not meaningful differences between both associations in signs or symptoms analyzed (pain, inflammation, aseptic cyst, fever, behavior alterations, diarrhea, encephalopathy, hypotonic-hyporesponsive episode or inconsolable weeping). With both associations the local reactions rate (0% of inflammation or aseptic cyst) and fever (10%) were very inferior to the previous published data. CONCLUSION: The vaccine association with a volume of injection of 1 ml did not produce more adverse effects than the association of 0,5 ml. Both produced a number of local reactions and fever much less than previously published, what is attributed to the prophylactic use of paracetamol and other preventive measures. Therefore, the association elected for the vaccination at 4 months (DTPw + Hib with a volume of 1 ml) is useful and practical to improve vaccine coverage and for the welfare of vaccinated infants, upon avoiding them an injection and without provoking more adverse reactions.