Use of sample size for estimating efficacy of a vaccine against an infectious disease.

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

OBJECTIVE: To determine the sample size necessary to evaluate the efficacy of a vaccine in a population. PROCEDURE: An equation was coded into a computer spreadsheet to compare the traditional sample size calculation with that needed when evaluating the efficacy of a vaccine applied in a population. RESULTS: The traditional approach used to conservatively estimate sample size necessary to detect a given difference in group proportions potentially greatly underestimates the number of animals needed for vaccine efficacy (VE) trials. In VE trials, it is necessary to estimate the effect of population-level vaccination prior to estimating sample size. In VE trials, as incidence proportion in the population or herd decreases or VE decreases, necessary sample size increases. CONCLUSIONS AND CLINICAL RELEVANCE: In designing a clinical or field trial, such as one to evaluate the efficacy of a vaccine against an infectious disease in a population, one needs to approach sample size calculations in a nontraditional manner. The proportion of the population vaccinated, disease transmission dynamics, and VE will affect the incidence in the nonvaccinated and vaccinated groups and, hence, sample size. Thus, estimation of the effect of the vaccination on the population must be made prior to calculating sample size. Otherwise, sample size and the power to identify VE will be insufficient.

Original languageEnglish (US)
Pages (from-to)1582-1584
Number of pages3
JournalAmerican Journal of Veterinary Research
Volume62
Issue number10
DOIs
StatePublished - Jan 1 2001

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Sample Size
infectious diseases
Communicable Diseases
Vaccines
vaccines
Population
sampling
Vaccination
vaccination
incidence
Incidence
disease transmission
clinical trials
field experimentation
herds

ASJC Scopus subject areas

  • veterinary(all)

Cite this

Use of sample size for estimating efficacy of a vaccine against an infectious disease. / Carpenter, Tim.

In: American Journal of Veterinary Research, Vol. 62, No. 10, 01.01.2001, p. 1582-1584.

Research output: Contribution to journalArticle

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