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Early two-dose measles vaccination schedule in Guinea-Bissau: good protection and coverage in infancy.
Int J Epidemiol. 1999 Apr; 28(2):347-52.IJ

Abstract

BACKGROUND

Previous studies from Africa have suggested that there is little benefit to be gained from early two-dose measles vaccination schedules. Two-dose schedules have been associated with no improvement in coverage due to immunization of the same individuals on both occasions, low return rate, high refusal rate, low vaccine efficacy, and fear of blunting of the antibody response. Because of the poor results achieved previously with two-dose measles vaccination schedules, we studied patterns of participation, reasons for non-participation, vaccination coverage and relative efficacy of a one-dose versus a two-dose schedule in connection with the implementation of an early two-dose trial in Guinea-Bissau.

METHODS

Children born from September 1994 to January 1996 were randomized into two groups receiving either two doses of measles vaccine at 6 and 9 months or one dose of inactivated polio vaccine (IPV) at 6 months and measles vaccine at 9 months.

RESULTS

At 6 months of age 86% (1869/2181) of the children participated, and at 9 months of age participation was 87% (1775/2035). The return rate for obtaining a second dose of vaccine was 93% (1647/1773). The main reason for not participating was travelling (78%). Around 50% of those who did not take part in one vaccination took part in the other. When only children participating the first time they were called for a measles vaccination were included, the measles vaccination coverage in the one-dose group was 59% versus 80% in the two-dose group, i.e. a 50% reduction in the risk of not being vaccinated (relative risk [RR] 0.50; confidence interval [CI]: 0.43-0.57). Few measles cases have occurred in the study area since the implementation of the trial making precise estimation of the relative efficacy of the two vaccine strategies difficult, but all seven clinically diagnosed measles cases occurred in the one-dose group making the relative efficacy for the two-dose group compared with the one-dose group 100% (95% CI: 35%-100%; two-tailed P = 0.016). When including maternal reports, the relative efficacy was 90% (95% exact confidence interval; two-tailed P = 25%-97%, P = 0.022).

CONCLUSION

In this study of a two-dose measles immunization schedule at 6 and 9 months of age there was no sign of low participation or poor return rates. The risk of not being vaccinated was lower in the two-dose group than in the one-dose group, and the relative efficacy of a two-dose versus a one-dose schedule was high. Although our results were obtained within a trial where dedicated personnel informed every participant personally about the study, we believe our results indicate that with thorough information about the population it may be possible to achieve a higher coverage with a two-dose measles vaccination schedule than a one-dose schedule. A two-dose schedule may be a feasible way to resolve the problems of low coverage and severe measles infection among infants.

Authors+Show Affiliations

Projecto de Saúde de Bandim, Bissau, Guinea-Bissau.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Comparative Study
Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

10342702

Citation

Garly, M L., et al. "Early Two-dose Measles Vaccination Schedule in Guinea-Bissau: Good Protection and Coverage in Infancy." International Journal of Epidemiology, vol. 28, no. 2, 1999, pp. 347-52.
Garly ML, Martins CL, Balé C, et al. Early two-dose measles vaccination schedule in Guinea-Bissau: good protection and coverage in infancy. Int J Epidemiol. 1999;28(2):347-52.
Garly, M. L., Martins, C. L., Balé, C., da Costa, F., Dias, F., Whittle, H., & Aaby, P. (1999). Early two-dose measles vaccination schedule in Guinea-Bissau: good protection and coverage in infancy. International Journal of Epidemiology, 28(2), 347-52.
Garly ML, et al. Early Two-dose Measles Vaccination Schedule in Guinea-Bissau: Good Protection and Coverage in Infancy. Int J Epidemiol. 1999;28(2):347-52. PubMed PMID: 10342702.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Early two-dose measles vaccination schedule in Guinea-Bissau: good protection and coverage in infancy. AU - Garly,M L, AU - Martins,C L, AU - Balé,C, AU - da Costa,F, AU - Dias,F, AU - Whittle,H, AU - Aaby,P, PY - 1999/5/26/pubmed PY - 1999/5/26/medline PY - 1999/5/26/entrez KW - Africa KW - Africa South Of The Sahara KW - Age Factors KW - Delivery Of Health Care KW - Demographic Factors KW - Developing Countries KW - Diseases KW - Guinea-bissau KW - Health KW - Health Services KW - Immunization KW - Infant KW - Measles KW - Population KW - Population Characteristics KW - Portuguese Speaking Africa KW - Primary Health Care KW - Research Report KW - Vaccination KW - Viral Diseases KW - Western Africa KW - Youth SP - 347 EP - 52 JF - International journal of epidemiology JO - Int J Epidemiol VL - 28 IS - 2 N2 - BACKGROUND: Previous studies from Africa have suggested that there is little benefit to be gained from early two-dose measles vaccination schedules. Two-dose schedules have been associated with no improvement in coverage due to immunization of the same individuals on both occasions, low return rate, high refusal rate, low vaccine efficacy, and fear of blunting of the antibody response. Because of the poor results achieved previously with two-dose measles vaccination schedules, we studied patterns of participation, reasons for non-participation, vaccination coverage and relative efficacy of a one-dose versus a two-dose schedule in connection with the implementation of an early two-dose trial in Guinea-Bissau. METHODS: Children born from September 1994 to January 1996 were randomized into two groups receiving either two doses of measles vaccine at 6 and 9 months or one dose of inactivated polio vaccine (IPV) at 6 months and measles vaccine at 9 months. RESULTS: At 6 months of age 86% (1869/2181) of the children participated, and at 9 months of age participation was 87% (1775/2035). The return rate for obtaining a second dose of vaccine was 93% (1647/1773). The main reason for not participating was travelling (78%). Around 50% of those who did not take part in one vaccination took part in the other. When only children participating the first time they were called for a measles vaccination were included, the measles vaccination coverage in the one-dose group was 59% versus 80% in the two-dose group, i.e. a 50% reduction in the risk of not being vaccinated (relative risk [RR] 0.50; confidence interval [CI]: 0.43-0.57). Few measles cases have occurred in the study area since the implementation of the trial making precise estimation of the relative efficacy of the two vaccine strategies difficult, but all seven clinically diagnosed measles cases occurred in the one-dose group making the relative efficacy for the two-dose group compared with the one-dose group 100% (95% CI: 35%-100%; two-tailed P = 0.016). When including maternal reports, the relative efficacy was 90% (95% exact confidence interval; two-tailed P = 25%-97%, P = 0.022). CONCLUSION: In this study of a two-dose measles immunization schedule at 6 and 9 months of age there was no sign of low participation or poor return rates. The risk of not being vaccinated was lower in the two-dose group than in the one-dose group, and the relative efficacy of a two-dose versus a one-dose schedule was high. Although our results were obtained within a trial where dedicated personnel informed every participant personally about the study, we believe our results indicate that with thorough information about the population it may be possible to achieve a higher coverage with a two-dose measles vaccination schedule than a one-dose schedule. A two-dose schedule may be a feasible way to resolve the problems of low coverage and severe measles infection among infants. SN - 0300-5771 UR - https://www.unboundmedicine.com/medline/citation/10342702/Early_two_dose_measles_vaccination_schedule_in_Guinea_Bissau:_good_protection_and_coverage_in_infancy_ L2 - https://academic.oup.com/ije/article-lookup/doi/10.1093/ije/28.2.347 DB - PRIME DP - Unbound Medicine ER -