Mt. Valenzuela et al., EFFICACY OF 2 TYPES OF BCG VACCINES ADMINISTERED IN DIFFERENT DOSES -A COMPARATIVE-STUDY, Revista Medica de Chile, 126(9), 1998, pp. 1126-1131
Background: In 1993, WHO and UNICEF recommended the administration of
0.05 mi doses of BCG, instead of 0.1 mi to newborns. This recommendati
on was adopted by the Chilean Ministry of Health, using the Merieux va
ccine. Subsequently, different Health Services detected a high percent
age of children without BCG scar at the time of their growth and devel
opment control. Aim: To assess the efficacy of BCG vaccination in a do
uble blind randomized fashion, using two vaccine types and different c
loses. Patients and methods: Newborns of two public hospitals of Santi
ago were randomly assigned to receive the Tokio or Merieux BCG strains
in doses of 0.05 or 0.1 ml. Ninety flue to 125 days after vaccination
, vaccine scar was measured anti inmunogenicity was assessed using the
tuberculin test. Results: Six hundred newborns (150 in each group) we
re included ill the protocol and results were assessed in 408. The per
centage of children with a PPD reaction of 0 mm was 9.3, 3.7, 7.8 and
0% with the Merieux vaccine in doses of 0.1 mi Tokio vaccines in close
s of 0.1 mi, Merieux vaccine in doses of 0.05 mi and Tokio vaccine in
doses of 0.05 ml, respectively. In the same groups the scar diameters
were 6.4 +/- 3.4, 7.3 +/- 2.7 5.6 +/- 2.8 and 7.3 +/- 2.9 mm. The obse
rved differences for each group are significant, depending on the type
of strain and dose, but favoring the Tokio type of vaccine. Conclusio
ns: The BCG scar diameters obtained in this study are similar to those
obtained in previous works in 1984 and 1986. This scar is the evidenc
e of vaccination that nurses detect in health controls. Therefore the
use of 0.1 doses for vaccination that result in better scars and PPD r
esponse, Is recommended.