Population-based Incidence
The population-based incidence for each virus overall and by age strata for year 1 and year 2 are shown in Figures 2a and 2b, respectively. Each year, RV/EV had the highest overall population-based incidence estimates (in year 1, 173 hospitalizations and in year 2, 204 hospitalizations per 100,000 persons). After RV/EV, in year 1, influenza A H3 had the highest overall incidence (69 hospitalizations per 100,000 persons) followed by the combined CoV types (65 hospitalizations per 100,000 persons) and in year 2, the combined CoV types had the highest overall incidence (91 hospitalizations per 100,000 persons) followed by influenza A H1 (52 hospitalizations per 100,000 persons).
Incidence increased with age for all viruses for both years and those> 80 years of age consistently had the highest incidence. The highest population-based incidence in those> 80 years of age for specific viruses was 660 hospitalizations per 100,000 persons for influenza A H3 in year 1 and 535 hospitalizations per 100,000 persons for the four combined human coronaviruses in year 2. Following RV/EV, the combined CoV types had the highest incidence estimates in both years among patients 18-49 and 50-64 years of age.
In year 1, the combined population-based incidence of all influenza viruses (A H1, A H3, and B) for all age strata was significantly lower than the combined population-based incidence of the non-influenza respiratory viruses including CoV types, RSV, PIV types, hMPV, and AV (125 vs. 208 hospitalizations per 100,000 persons, respectively, p<0.001). Similarly, in year 2, the combined population-based incidence of influenza viruses was significantly lower than that of these non-influenza respiratory viruses (96 vs. 244 hospitalizations per 100,000 persons, respectively, p<0.001).