Abstract
We recently experienced a patient with viral isolation by culture 4 months after the acute infection. an 83-year-old Japanese man visited our outpatient clinic with symptoms of upper respiratory tract infection. The patient was diagnosed with a COVID-19 infection by a quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) test. Three months after his clinic visit, he had regained most of his pre-COVID-19 level of health. However, qRT-PCR tests continued to be positive. At day 111, specimens from a nasopharyngeal swab and sputum were inoculated into VeroE6/TMPRSS2 cells.(1) Three to five days post-inoculation, cytopathic effects were observed, and viral RNA was detected in the culture supernatant by qRT-PCR (Ct values: 29–37). The culture supernatant of the VeroE6/TMPRSS2 cells cocultured with the nasopharyngeal swab was passaged to the fresh VeroE6/TMPRSS2 cells, and after 3 days of the passage, cytopathic effect was observed again. In the supernatant of the passaged cell culture, viral RNA was detected by qRT-PCR (Ct value: 29). By sequencing the qRT-PCR product using Illumina iSEQ100, the presence of SARS-CoV-2 RNA sequence was verified. These results indicate the presence of infectious SARS-CoV-2 in the nasopharyngeal specimen even at day 111. Although SARS-CoV-2 was present, the patient developed neutralizing antibodies by a microtiter method. We tested but did not isolate SARS-CoV-2 in samples of saliva, urine, blood, or stool. Patients with ongoing symptoms of COVID-19, long-haulers, could be chronically infected with COVID-19, although they might be incapable of transmission.