In our study, individuals with very serious disease who did not have exacerbations did not have any other features distinguishing them from sufferers with exacerbations aside from the truth that they did not statement exacerbations in the preceding 12 months. Although exacerbation frequency was associated with health status over the GOLD stages and in patients with moderate disease, this is incorrect among patients with the most severe disease . Whether this pattern reflects the smaller number of patients with very severe disease or a survivor effect among patients with severe disease who were taking part in a longitudinal research can’t be established. Another possibility is that in sufferers with very serious COPD, the role of exacerbations in compromising health status is less important than that of the severity of the underlying disease itself.This age-related impact was reflected in every measures of immunogenicity. In general, the design of antibody responses, as measured by the microneutralization assay, was similar to those noticed with the hemagglutination-inhibition assay . Baseline microneutralization GMTs in younger age group were significantly greater than those in the older generation . Postvaccination microneutralization GMTs were also considerably higher in younger generation than in the older age group, no matter dose .