Figure 2.

Kaplan–Meier survival estimates of the associations of vaccine type with hospitalization stratified by age. Receipt of High Dose as Compared with Standard Dose Influenza Vaccine Associated with Reduced Hospitalization in 2016-17, not in 2015-16. In 2015–2016, there was no significant association of vaccine type (standard dose trivalent, standard dose quadrivalent, and high-dose trivalent) with time to first hospitalization among patients <65 years of age (A) or ≥65 years of age (B). In 2016–2017, there was a significant association of high dose with reduced hospitalization in the full population (Table 3). When stratified by age, the association was significant in patients ≥65 years of age, but not in those <65 years of age. However, an interaction term of age group with age did not reach statistical significance (details are in the text).