The Covid-19 Pandemic which began in late 2019 has rapidly spread to all quarters of our planet, with cases and deaths continuing to rise globally. While suppression measures (e.g. lockdowns, social distancing, hand hygiene) have had significant impacts on curtailing the spread of the SARS-CoV-2 virus, such measures are temporary, can be cyclical, and have multiple negative impacts on our societies and economies.
Until there is vaccination of sufficient numbers of people globally (there are 7.8 billion people on the planet) to ensure a herd immunity effect against the virus, the SARS-CoV-2 virus will continue to circulate in our communities and countries for years ahead.
Diagnostic Testing and Surveillance or Mass Screening for presence of the SARS-Cov-2 virus are related but distinct approaches that can be used for monitoring, managing and limiting the spread of the SARS-CoV-2 coronavirus in our communities and society.
In Ireland, diagnostic testing for SARS-CoV-2 is currently based on taking a nasal swab sample from each person who displays Covid-19 symptoms and testing for the presence of the virus by quantitative real-time PCR (qRT-PCR). Despite being considered the “gold standard” for clinical diagnostics, the nasal swab sampling is time-consuming, cumbersome, costly and uncomfortable for those being sampled. In addition, nasal swab sampling for Covid-19 testing is not possible to scale up to large numbers for serial mass-testing or screening thousands of people, or indeed entire populations.
Surveillance or mass screening for Covid-19 involves serial screening of large numbers of asymptomatic people on a recurring basis to determine the prevalence of the virus in society (or a population). Surveillance screening can be done by either qRT-PCR or antigen testing. Such screening can allow us to determine whether the prevalence of the virus (i.e. number of people infected in a population) in society is increasing or decreasing over time (e.g. in response to lockdowns, shifts from one suppression Level to another, vaccine roll-out etc). Surveillance screening can also be used to identify pre-symptomatic or asymptomatic people who may inadvertently be spreading the virus to their close contacts.
Large-scale mass testing or surveillance screening of populations or groups in society on a serial (i.e. recurring) basis is an extremely powerful “pre-screening” approach that can allow infected people to be quickly identified, who can then be advised that they should follow HSE guidelines (including to get themselves clinically tested using the standard nasal swab qRT-PCR diagnostic test).
Funded by Science Foundation Ireland (SFI), the Genetics & Biotechnology Lab of Prof. Charles Spillane in the Ryan Institute at NUI Galway has developed a high-throughput qRT-PCR saliva testing system for screening large numbers (e.g. 1000s of samples per day) of saliva samples per day for presence of the SARS-Cov-2 virus. The SpillaneLab has established a lab capacity to screen 1000s of saliva samples per day for presence of the SARS-CoV-2 virus by the gold standard qRT-PCR assay, which can be used for surveillance screening of societal groups. In the SalivaScreen research project, the SpillaneLab are using their Covid-19 saliva screening system to conduct surveillance screens with different groups to develop screening based systems for improved management of the virus in different settings and groups.
With some further investment, the number of saliva samples that the SpillaneLab could process per day can be potentially scaled up to screening 10s of 1000s of saliva samples per day allowing serial mass-testing of groups and large-scale surveillance studies in the period up to (and including) the vaccine roll-out period.