Cleaning and disinfecting procedures have become more important in several industries since the COVID-19 pandemic happened, particularly in the healthcare sector. Standard procedures and protocols have been revised to better adapt to the coronavirus situation, and scientists are continually looking into new ways to improve these procedures.
Medical experts at John Hopkins have been exploring the use of ultraviolet (UV) light in disinfecting medical equipment, particularly CT scan machines. The inner bore of CT scan machines is more exposed to exhaled particles from the different patients that use them, making them highly susceptible to contracting the virus. While the most common UV rays that hit the earth are classified ultraviolet-A, this light can cause skin cancer and other problems upon exposure, so Siewerdsen and Mahesh opted to test ultraviolet-C (UVC) rays instead since they’ve been known to eliminate a high proportion of SARS-CoV-2 virus from hard surfaces.
Biomedical engineer Jeff Siewerdsen and radiologist Mahadevappa MaheshIt utilized a lamp that emits UVC light to the bed inside the CT scanner to determine if it can successfully reduce virus particles. The experiment proved to be successful, as early results revealed that the UVC light coming from the $105 lamp project was able to eliminate 99.9999% of SARS-CoV-2 virus particles inside the bore in just three to five minutes. They published a summary of their study, accompanied by a video abstract, on November 18 in the Journal of Applied Clinical Medical Physics.
On a different note, researchers have been repeatedly testing for SARS-CoV-2 during the ongoing pandemic in order to isolate the COVID-19 patients and to lower the number of infected individuals. The tests are usually performed on people that are manifesting symptoms or to the ones that were exposed to COVID-19 positive individuals, even without any symptoms.
However, recent research has revealed that even though the genetic material of SARS-CoV-2 can be detected through molecular testing after a few weeks of symptoms, it does not mean that infectious virus particles are present. A study by researchers at Johns Hopkins Medicine and the Johns Hopkins Bloomberg School of Public Health has provided more understanding about the detection of the virus while also showing its contagiousness.
In their study, the researchers evaluated almost 30,000 nasopharyngeal swab results of repeated polymerase chain reaction (PCR) diagnostic tests. The number of times a PCR takes to get a positive signal is called the cycle threshold (Ct). A low Ct score indicates a large amount of SARS-CoV-2 RNA and a high one means a fewer amount of the genetic material.
The experiments’ results revealed that the average Ct value associated with cell culture growth of SARS-CoV-2 was 18.8. The researchers also detected viral growth from specimens collected up to 20 days after the first positive result. Sequencing of the entire genome from RNAs collected in the first and subsequent tests provided evidence that the same virus was seen throughout. Positive tests following negative ones had Ct values higher than 29.5, and were not associated with observed virus growth in culture.
According to Dr. Andrew Pekosz, professor of microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health and co-senior author of the study, additional studies need to be conducted to confirm if Ct values and cell cultures are accurate enough to make clinical decisions for diagnosis. “Defining the window of time in which a COVID-19 patient can transmit the virus can help drive more effective isolation practices,” Dr. Pekosz explains.
(Source: Science Codex)
