[Flu vaccine effectiveness: a metaanalysis]

Abstract

Introduction: Seasonal influenza is a disease of great interest in public health due to its high rates of infection and big costs, especially in high-risk population. This situation has motivated studies related to development of control measures necessary to mitigate its impact. Immunization constitutes a key role in providing the necessary interventions; however, little information is available about its effectiveness as public health measure in tropical countries.

Objective: The vaccine effectiveness was evaluated by means of published results in the scientific literature.

Materials and methods: Meta-analysis techniques were used to summarize the results of epidemiological analytical studies. A critical evaluation was undertaken for each study to identify the potential biases and methodological limitations.

Results: Two hundred and fifty-seven relevant studies were located, of which 28 were included in the analysis. The pooled estimator of the vaccine effectiveness for hospitalization was 0.74 [95% CI 0.68-0.81] in older adults (65 years and older) in cases-control studies. For cohort studies, the obtained estimator was 0.80 [95% CI 0.68-0.91].

Conclusion: Other conclusions were analyzed, and in general, a protective effect was demonstrated in the vaccine. About 1,200,000 were involved, 530,000 of them were vaccinated. Geographically, the analyzed studies came from developed countries in Europe, America and Asia.