A Study to Learn How Effective is PCV20 to Help Stop Adults Who Have a Higher Chance of Getting Pneumonia

The purpose of this study is to learn how well PCV20 stops adults from getting community-acquired pneumonia. Pneumonia is an infection of the lungs that can be caused by germs like bacteria, virus, or fungi. This study uses existing healthcare information. No participants will be actively enrolled. The information of participants will be taken from Kaiser Permanente Southern California's (KPSC) electronic health records (EHR). We will look at the EHR information for adults who meet the following points: * 19 years of age or older and a KPSC member between 01 July 2022 and 31 May 2025. * have higher risk of pneumococcal disease due to older age or a chronic medical condition * have been a KPSC member for the year before joining the study and for at least one year before 01 July 2022. * have not received PCV15, PCV21, PPSV23 (2 years before), or PCV13 (5 years before) joining the study. * have not received PCV20 before 01 June 2022. * have not received PCV20 before turning 65 or before having a chronic medical condition which has higher risk of pneumococcal disease. * have had at least one outpatient visit. * have not had pneumonia or lower respiratory tract infection within 30 days of joining the study. The study will begin on 01 July 2022 and end on 30 June 2025. At the end of the follow-up period, the study will compare the number of community-acquired pneumonia cases among people who did and did not receive PCV20.