Lack of efficacy of the standard potency Edmonston-Zagreb live, attenuated measles vaccine in African infants.
The efficacy of standard potency Edmonston-Zagreb (E-Z) measles vaccine was tested in a randomized trial of Black infants in a rural area of South Africa where a measles epidemic was occurring. The following immunization schedules were used: 48 infants aged 4-8.5 months who received 3.9 log 50 infectious units of E-Z vaccine (group A); 48 infants aged 4-8.5 months who received 3.28 log 50 infectious units of Schwarz vaccine (group B); and 28 infants aged greater than 9 months who received 3.28 log 50 infectious units of Schwarz vaccine and served as controls (group C). For infants aged less than 23 weeks who were given either the E-Z or Schwarz vaccine, the number of seropositives was low (28%), irrespective of the pre-vaccination level of measles antibody. There was a higher number of seropositives (68%) among those in the age range greater than 23 weeks to less than 36 weeks who received the E-Z vaccine rather than the Schwarz vaccine (36%). When administered to children aged greater than 36 weeks, the Schwarz vaccine produced a satisfactory, though suboptimal response rate (61%). There was no correlation between seropositivity and pre-vaccination measles antibody status. Use of the standard dose of E-Z vaccine may have been one of the factors for this poor response, and this supports the WHO recommendation that titres higher than the standard potency vaccine are needed if 6-month-old infants are to be successfully immunized against measles.
Kiepiela
P
P
Department of Paediatrics and Child Health, Faculty of Medicine, University of Natal, Durban, South Africa.
Coovadia
H M
HM
Loening
W E
WE
Coward
P
P
Botha
G
G
Hugo
J
J
Becker
P J
PJ
D006801:Humans; D007126:Immunoglobulin Allotypes / Q000032:analysis; D007074:Immunoglobulin G / Q000276:immunology; D007223:Infant; D008457:Measles / Q000097:blood / Q000453:epidemiology* / Q000276:immunology; D008458:Measles Vaccine / Q000592:standards*; D012424:Rural Population; D016036:Seroepidemiologic Studies; D013019:South Africa / Q000453:epidemiology
D007126:Immunoglobulin Allotypes; D007074:Immunoglobulin G; D008458:Measles Vaccine