No evidence for short or long term morbidity after increased titer measles vaccination in Sudan.
BACKGROUND
Increased mortality rates have been reported after high titer measles [>10(5.0) plaque-forming units (PFU)] vaccination in several large studies in the developing world. An increased titer measles vaccine study conducted in Sudan included a prolonged prospective evaluation of childhood morbidity after vaccination.


METHODS
Five hundred ten children (170 per group) were randomized to receive 1 of 3 regimens at 5 and 9 months of age: (1) meningococcal vaccine, then standard titer (50% tissue culture-infective dose, 103.8) Schwarz measles vaccine; (2) increased titer (10(4.7) PFU) Edmonston-Zagreb measles vaccine followed by meningococcal vaccine; and (3) increased titer (10(4.7) PFU) Connaught vaccine followed by standard titer Schwarz measles vaccine.


RESULTS
Health workers collected information at 31,582 semi-monthly and monthly visits during 5 years. No increase in infant mortality was observed, but the statistical power was limited. There were 13, 13 and 10 deaths in the Schwarz, Edmonston-Zagreb and Connaught groups, respectively. There were no differences in duration or incidence of illness between groups at any time during the 5-year follow-up, with comparisons stratified by age and sex. Statistical power for each pairwise comparison was good, with at least 80% power to detect a difference of 1 day per month of illness and a 12% difference in the proportion of visits with an illness recorded.


CONCLUSIONS
We were unable to document increased morbidity in recipients of the increased titer measles vaccines used in this study. These data do not support the hypothesis that increased mortality after increased titer vaccine exposure is the result of increased and cumulative morbidity.
Libman
Michael D
MD
Microbiology Department, Montreal General Hospital, McGill University, Montreal, Quebec, Canada. Michael Libman@mcgill.ca
Ibrahim
Salah A
SA
Omer
Mohamed I A
MI
Adlan
Ibrahim A
IA
Bellavance
François
F
Hoskins
Eric
E
Bertley
Frederic
F
Ward
BrainJ
B
D000367:Age Factors; D003906:Developing Countries; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008297:Male; D008458:Measles Vaccine / Q000008:administration & dosage / Q000009:adverse effects*; D009017:Morbidity; D009026:Mortality; D012737:Sex Factors; D013397:Sudan
D008458:Measles Vaccine