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Lancet. 1999 Jan 30;353(9150):355-8.

Risk of diphtheria among schoolchildren in the Russian Federation in relation to time since last vaccination.

Author information

1
Epidemiology and Surveillance Division, National Immunization Program, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA. cxv3@cdc.gov

Abstract

BACKGROUND:

Between 1990 and 1996, more than 110,000 cases and 2900 deaths from diphtheria were reported in the Russian Federation. In 1994, because disease rates were high among children aged 7-10 years, the age of administration of the second booster dose of diphtheria vaccine was lowered from 9 years to 6 years, the age of school entry. To assess the impact of this policy change, we did a matched case-control study in three Russian cities.

METHODS:

Children aged 6-8 years who had diphtheria between September, 1994, and December, 1996, were each matched with five to seven children acting as controls who were within 3 months of age of the case and were from the same class at school. We did a matched analysis using conditional logistic regression.

FINDINGS:

We analysed the immunisation records of 58 cases and 306 controls. All but one case and all controls had received at least three doses of diphtheria-toxoid vaccine. 19 (33%) cases and 144 (47%) controls had received a booster dose of diphtheria toxoid within the previous 2 years. Cases were more likely than were controls to have received only four doses rather than five (odds ratio 2.8 [95% CI 1.2-6.5]) and to have a time since the last dose of diphtheria toxoid of 3-4 years (3.1 [1.1-9.1]) or 5-7 years (15.0 [2.5-89.0]), compared with children for whom it was 2 years or less. On multivariate analysis only a time since the last dose of 5-7 years remained significantly associated with disease (matched odds ratio adjusted for total number of doses 10.9 [1.6-75.1]).

CONCLUSION:

A booster dose of diphtheria-toxoid vaccine given to children in the Russian Federation at 6-8 years of age reduced the interval since the last dose of diphtheria toxoid and improved protection against diphtheria.

PIP:

More than 110,000 cases and 2900 deaths from diphtheria were reported in the Russian Federation in 1990-96. In response to the high disease rates in children 7-10 years of age, the timing of the second booster dose of diphtheria vaccine was lowered in 1994 from 9 to 6 years of age--the age of school entry. The impact of this change was assessed in a matched, retrospective, case-control study conducted in three Russian cities. 58 children 6-8 years old who had diphtheria between September 1994 and December 1996 were matched with 306 controls within 3 months of age and from the same school class. All but one case and all controls had received at least three doses of diphtheria toxoid vaccine and 19 cases (33%) and 144 controls (47%) had received a booster dose of the vaccine within the previous 2 years. Cases were more likely than controls to have received 4 rather than 5 doses (odds ratio (OR), 2.8; 95% confidence interval (CI), 1.2-6.5) and to have an interval since the last vaccine dose of 3-4 years (OR, 3.1; 95% CI, 1.1-9.1) or 5-7 years (OR, 15.0; 95% CI, 2.5-89.0) compared with children for whom it was 2 years or less since the last dose. In the multivariate analysis, only time since the last vaccine dose of 5-7 years was significantly associated with disease (matched OR adjusted for total number of doses, 10.9; 95% CI, 1.6-75.1). These findings indicate that a booster dose of diphtheria toxoid at the age of school entry is effective in preventing diphtheria among school-aged children. This evidence should be considered in the development of routine childhood immunization schedules in countries where diphtheria remains endemic.

PMID:
9950440
DOI:
10.1016/S0140-6736(98)03488-6
[Indexed for MEDLINE]

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