The association between baseline viral load and long-term risk in patients with COVID-19 in Hong Kong: a territory-wide study

COVID-19 can increase the long-term risk of multiorgan dysfunction. Few studies investigated the long-term risk in Asian populations or investigated the association between viral load and long-term risk. We aimed to investigate the post-discharge rates of hospitalization and association with baseline viral load in all patients with COVID-19 in Hong Kong. This was a population-based cohort study included all patients with a positive RT-PCR test for SARS-CoV-2 in Hong Kong between January 1st 2020 and August 30th 2020, routinely admitted to public health care facilities for isolation and treatment. Viral Ct values were available in 3433 (85%) of patients. Outcomes of interest included death, cause-specific hospitalizations, and initiation of medication from the Hospital Authority's territory-wide electronic health records from the Clinical Data Analysis and Reporting System. In total, 4054 people in Hong Kong tested positive for COVID-19 and were admitted to a public health care facility, of whom 167 (4.1%) were admitted to ICU. During a median follow-up time of 251 (interquartile range 240-279) days, 408 (11.9%) were hospitalized for any reason and 16 (0.5%) patients died. After discharge, patients were most often readmitted for respiratory reasons, followed by gastro-intestinal reasons. A higher viral load (lower RT-PCR Ct values) was associated with a higher likelihood of death (Hazard ratio [HR] 5.86, 95% Confidence interval [CI] 2.57-13.33), hospitalization (HR 1.22, 95%CI 1.08-1.39) or hospitalization for cardiovascular disease (HR 12.78, 95%CI 3.67-44.48). Patients with higher viral loads more likely started ACE-inhibitors (HR 1.37, 95%CI 1.12-1.68) and non-opioid analgesics (HR 1.01, 95%CI 1.01-1.23). In a relatively mild COVID-19 population from Hong Kong, the post-acute risk of complications was substantial. Our results highlight that higher viral load predict post-acute complications in patients with relatively mild disease.