Number needed to vaccinate
From Wikipedia, the free encyclopedia
Number needed to vaccinate (NNV) is a metric used in the evaluation of vaccines,[1][2][3] and in the determination of vaccination policy. It is defined as the average number of patients that must be vaccinated to prevent one case of disease. It is a specific application of the number needed to treat metric (NNT).
NNV is the inverse of the absolute risk reduction of the vaccine. If the incidence in the vaccinated population is , and the incidence in the unvaccinated population is , then the NNV is .
For example, one study reported a number needed to vaccinate of 5206 for invasive pneumococcal disease.[4]