To date assessments of the viral levels within the community have been undertaken through individual sampling, such as nasal and saliva samples. Progress has also been made through environmental surveillance, such as examination of viral levels in wastewater effluent (as Digital Journal has previously reported).
While these methods can act as important epidemiological indicators of community infection dynamics as well as for disease prevalence, there are other techniques that can also be considered in order to build up a bigger picture of the spread of the disease. This is where the examinaton of dust particles comes in.
This new technique of dust analysis is particularly important for assessing SARS-CoV-2 levels at the building scale. This is especially so within higher-risk settings such as care homes and hospitals.
The basis of the method is to assess for levels of RNA relating to SARS-CoV-2 drawn from surface swabs, plates, and with bulk dust samples collected from rooms. To gather positive data, airborne samples were collected from rooms known to have been frequented by people who had tested positive for COVID-19.
Any traces of SARS-CoV-2 viral RNA were assessed using quantitative reverse transcription polymerase chain reaction (RT-qPCR) together with two digital PCR (dPCR) methods.
The data showed dust was the most efficient sample type for the detection of SARS-CoV-2 viral RNA. In the rooms occupied by COVID-19 cases, it was found that 88 percent of bulk dust samples tested positive for the coronavirus. Important for retrospective analysis, the researchers discovered that viral RNA in bulk dust did not degrade following 4 weeks.
It is important to note that the study did not measure SARS-CoV-2 infectivity. However, the data does provide an approach to assess dust as a suitable matrix for environmental monitoring of the coronavirus. Instead of individual monitoring, the approach measures spaces occupied by larger numbers of people. The researchers contend that technique may have a greater use as the larger percentage of the population receives a vaccine, resulting in individual monitoring becoming become less feasible.
Sample collection may become straightforward, given that indoor dust is collected through standard cleaning procedures in many buildings.
The research appears in the American Society of Microbiology journal mSystems, where the paper is titled “Indoor Dust as a Matrix for Surveillance of COVID-19.”
