Long-Term Study of COVID-19 Infection and Long COVID

This study will examine how common Long COVID is and how symptoms may persist over time in people who have previously had COVID-19. Researchers will collect information about participants' health and symptoms through questionnaires and may collect saliva and other non-invasive oral samples. The study will also examine biological factors in these samples that may be associated with persistent symptoms. The goal is to better understand why some people develop Long COVID and identify factors that may help predict who is more likely to experience persistent symptoms.

Inclusion Criteria: * Age 18 to 75 years. * Previous laboratory-confirmed SARS-CoV-2 infection. * Willing and able to provide informed consent. * Able to complete study questionnaires and study procedures. Exclusion Criteria: * Current severe periodontal disease with bleeding gums. * Current oral herpes flare, aphthous ulcer, or oral candidiasis (thrush). * Oral viral or bacterial infection within the previous 30 days. * Dry mouth that would prevent adequate saliva collection. * Active alcohol or drug abuse. * Medical or genetic syndrome or developmental delay that would prevent completion of study procedures or questionnaires.