inclusion criteria: - ≥18 years old when enrolled; - participants signing the informed consent; - being able to participate in all planned follow-ups and accomplish all research procedures including completing a diary card and coming back for interview; - having not been administered any pneumonia vaccine or covid-19 vaccine, and having not been administered an influenza vaccine in the current season before enrollment; - ≥14 days from the most recent vaccination; - before enrollment, the body temperature is ≤37.0c as confirmed by medical history and clinical examination.

inclusion criteria: - ≥18 years old when enrolled; - participants signing the informed consent; - being able to participate in all planned follow-ups and accomplish all research procedures including completing a diary card and coming back for interview; - having not been administered any pneumonia vaccine or covid-19 vaccine, and having not been administered an influenza vaccine in the current season before enrollment; - ≥14 days from the most recent vaccination; - before enrollment, the body temperature is ≤37.0c as confirmed by medical history and clinical examination.