Serial viral load was ascertained by reverse transcriptase quantitative PCR (RT-qPCR). We obtained samples of blood, urine, posterior oropharyngeal saliva, and rectal swabs. We included patients with laboratory-confirmed COVID-19. We did a cohort study at two hospitals in Hong Kong. We aimed to ascertain the serial respiratory viral load of SARS-CoV-2 in posterior oropharyngeal (deep throat) saliva samples from patients with COVID-19, and serum antibody responses. Nasopharyngeal and throat swabs are usually obtained for serial viral load monitoring of respiratory infections but gathering these specimens can cause discomfort for patients and put health-care workers at risk. Comprehensive data for serial respiratory viral load and serum antibody responses from patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are not yet available. Electronic address: disease 2019 (COVID-19) causes severe community and nosocomial outbreaks. 8 Department of Clinical Microbiology and Infection Control, The University of Hong Kong-Shenzhen Hospital, Shenzhen, China.7 Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China.6 State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China.5 Department of Pathology, Queen Elizabeth Hospital, Hong Kong Special Administrative Region, China.4 Department of Medicine, Queen Elizabeth Hospital, Hong Kong Special Administrative Region, China.3 Department of Medicine, Queen Mary Hospital, Hong Kong Special Administrative Region, China.2 Department of Medicine and Geriatrics, Princess Margaret Hospital, Hong Kong Special Administrative Region, China.1 State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China Department of Clinical Microbiology and Infection Control, The University of Hong Kong-Shenzhen Hospital, Shenzhen, China.