According to research research conducted in Wuhan and published on April 9 in following article, https://www.kidney-international.org/article/S0085-2538(20)30369-0/fulltext, out of 26 autopsies conducted on people who died of Covid-19, nine of which had acute kidney injury, seven were found to have clusters of coronavirus particles with distinctive spikes in the tubular epithelium and podocytes on electron microscopy. In addition, immunostaining with SARS-CoV nucleoprotein antibody was shown to be positive in tubules. Other case reports indicating extra-pulmonary involvement have surfaced including hepatitis, myocarditis along with arrhythmias, and thromboses. I have not seen any histopathology reports indicating direct viral infection of other organ systems besides lung and kidney, but the above would seem to suggest that there should be a viremic phase associated with this illness. Have there been any studies of blood viral loads or qualitative pcr measurements taken of hospitalized patients with this illness?
There was this one study I was able to find (although it seems to just be a single case report), where an infant was found to have COVID-19 viremia. They did RT-PCR on blood samples on day 2 after admission and were able to find the cycle threshold (Ct) as 32.9-33.9.
(the link to the full original report is also available in the pdf above, but most of the key points can be found under the section titled "One-Minute Summary")
This was more of a study to see whether virus could be detected at different sites. 39 patients were tested. Interestingly those who were viremic didn't test positive to swabs.
We know that SARS-CoV-2 can attach to ACE2 receptors and these are found on macrophages. There's also some speculation based on modelling that it binds to hemoglobin impairing oxygen carriage.
We found 15 patients who still carry virus following days of medical treatments. Of these patients, 8 were oral swabs positive (53.3%), 4 were anal swabs positive (26.7%), 6 blood positives (40%) and 3 serum positives (20%). Two patients were positive by both oral swab and anal swab, yet none of the blood positive was also swabs positive. Not surprisingly, all serum positives were also whole serum positive (Table 1). In summary, viral nucleotide can be found in anal swab or blood even if it cannot be detected in oral swabs. It should be noted that although swabs may be negative, the patient might still be viremic.