Limitations
Some of the limitations of our study were that a considerable number of
participants dropped out during the study, this study was only performed
in one medical center, and that we could not perform genetic sequencing
to prove infection with a different clade of the virus, or cultures to
prove presence of replication-competent virus. The diagnosis of
re-infection in our study is based on RT-PCR results, typical symptoms
and the long interval between the two positive results. And, since we
did not measure the viral load in patients who tested positive, the
diagnosis of re-infection in our study is as certain as is the
specificity of the RT-PCR test. We were also unable to perform required
serology testing from the beginning of the study.