No correlation between Ct values of PCR test and COVID-19 severity

Using the cycle threshold (Ct) values to infer COVID-19 disease severity or infectiousness may be problematic. Cycle threshold values can be suggestive of the amount of virus in an infected person but there is no reliable way of correlating the Ct value with COVID-19 disease severity or infectiousness. But largely, when the Ct value is over 35, a person is unlikely to be infectious. There are many variables that can alter the Ct value of a sample.