a significant trendp < 0.001
The frequency of hospitalization stratified by age groups showed an increase from 55.26% in 2002 to 74.92% in 2016 in the <1 year age class ( Figure 1 ) with a significant trend (β = 1.37; p < 0.001).
The frequency of hospitalization stratified by age groups showed an increase from 55.26% in 2002 to 74.92% in 2016 in the <1 year age class ( Figure 1 ) with a significant trend (β = 1.37; p < 0.001).
An increasing trend of hospitalization frequency emerged for the age group with levels of IgG antibodies to pertussis toxin compatible with pertussis infection within the last year (20–29 years old age group).