Table 3

Numbers needed to vaccinate for preventing one case of community acquired pneumonia, acute myocardial infarction or ischaemic stroke by pneumococcal vaccination in people 60 years or older

Outcome

Attributable Risk

per 1000 person/year

Number Need to Vaccinate


ARa

95% CIb

NNVc

95% CI

(lower to higherd)


Community acquired pneumonia

1.067

-1.139 to 3.327

938

306 to -878


Acute myocardial infarction

0.423

-1.341 to 2.187

2,365

458 to -746


Ischaemic Stroke

1.788

0.177 to 3.399

560

295 to 5649


a Attributable Risk = incidence rate difference between unvaccinated and vaccinated subjects.

b CI denotes confidence interval.

c NNV is the number needed to vaccinate for preventing one case and is estimated as 1/AR.

d The negative numbers in the high limit of confidence interval indicate that NNV tends to infinite and it is not statistically significant.

Vila-Corcoles et al. BMC Public Health 2012 12:222   doi:10.1186/1471-2458-12-222

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