Abstract
The COVID-19 pandemic causes sudden public panic and people take appropriate precautions by wearing masks, physical distancing in public according to new-normal life style. If an antiseptic can exert rapid virucidal effect with prolonged activity on SARS-CoV-2 that accumulate on nasal, buccal and pharyngeal epithelia, it can help prevent the spread of the virus from infected persons to healthy people including medical personnel during resuscitation, treatment or transportation. Numerous existing in vitro data have confirmed that povidone-iodine (PVI) inactivates many common respiratory viruses, including SARS-CoV-2 approximaltely 100 folds in less than one minute of PVI exposure. Povidone-iodine also has good profile for mucosal tolerance in upper aerodigestive tract. Thus, we propose a pilot study to demonstrate its virucidal efficacy of SARS-CoV-2 by the application of topical PVI or diluted solution of PVI to the upper aerodigestive tract in infected patients using the self comparison study design method. The first three serial pilot studies recruited 55 infected patients and illustrated that SARS-CoV-2 could be detected by the RT-PCR in both specimens of nasopharyngeal and throat swabs but the Ct values of throat specimens were usually higher compared to the nasal specimens in the same patient and at the same time of specimen collection. Viable SARS-CoV-2 was detected only from nasopharyngeal specimens with Ct values equal or less than 25 using vero-E6 cells for tissue culture. Viable SARS-CoV-2 cannot be cultured from throat or tongue samples which made oral samples inappropriate for the demonstration of virucidal effect of PVI. The fourth study in 14 patients revealed viable culture was obtained from 12 patients and involved only nasopharyngeal specimens. After 3 minutes of contact time with nasal spray of PVI or 0.4% PVI solution, a median value of 1.1 log reduction of viable viruses (IQR: 0.6-1.7 log reduction) or 90.7% virus reduction (median; IQR: 75.0%-98.0%) were found. After 4 hours of contact, a median value of 0.8 log reduction (IQR: 0.4-1.8 log reduction) or 81.3% virus reduction (IQR: 56.3%-98.4%) were found. The amount of virus reduction after PVI contact and speed of virucidal activity were much less impressive than the results from the in vitro study. In conclusion, we were able to consistently culture viable SARS-CoV-2 in vero-E6 cells only from nasopharyngeal specimens in newly infected patients who had Ct value equal or less than 25 from RT-PCR testing. Viable SARS-CoV-2 can not be cultured from any oropharyngeal samples. Commercial PVI nasal spray or 0.4% PVI solution have minimally, if there is any, virucidal activity in nasal cavities of infected patients after PVI exposure for three minutes and four hours. This level of virucidal activity from the study may not be significant to prevent the spread of COVID-19. The PVI nasal spray and 0.4% PVI solution were very safe, very tolerable without any side effect.
