The coronavirus reaches the UK – the importance of early detection
17 February 2020
The world is in the midst of an outbreak of a serious, highly infectious respiratory disease called Coronavirus. The disease, officially designated COVID-19 (for COronaVIrus Disease-2019), was first reported in the city of Wuhan in China on 31 December 2019 and was declared a Public Health Emergency by the World Health Organisation on 30th January 2020. The next day, the first 2 cases in the UK were confirmed, among the 7,818 confirmed cases globally. As of 13th February 2020, there are 9 cases in the UK and 45,171 globally across over 25 countries. Whilst the Department of Health have described the coronavirus as a “serious and imminent threat to public health”, the overall risk level to the UK remains “moderate.”
The coronavirus family
The coronavirus family of viruses cause disease in both mammals and birds, meaning it is a zootonic virus; COVID-19 is thought to have originated in bats and then infected a second animal species, before jumping the species barrier once more to infect humans. There are nine known strains of coronavirus, all of which cause respiratory tract infections in humans, including three that cause the common cold, as well as the strain responsible for the SARS-CoV (severe acute respiratory syndrome) virus that was responsible for the outbreak between November 2003 and July 2004.
While the COVID-19 is related to the SARS-CoV, there are still considerable differences between the viruses, notably in their infection rate; the number of cases of SARS was 8,422 over the entire course of the nine month epidemic, while COVID-19 caused over 40,000 identified cases in within three months. One other critical difference is the mortality rate of COVID-19, which so far seems to be about a fifth of that of SARS-CoV; for every 100 cases of COVID-19, there are approximately 2 fatalities, compared to 1 in 10 fatalities for SARS-CoV. However, the strains are similar enough to allow us to learn from history as to how best to deal with the disease.
What measures are being taken to prevent the spread of coronavirus?
With no vaccine or cure available yet, affected countries including the UK are trying to contain the spread of the illness in a similar manner to SARS-CoV by (i) isolating and treating infected individuals, including quarantining groups of potentially infected individuals (ii) determining those who may have been in close contact with infected individuals and monitoring them for signs of infection and (iii) informing the public of appropriate social distancing measures such as remote working, suspension of school classes and suspension of religious gatherings to limit contact between humans and therefore slow the spread of the infection.
The importance of rapid detection
Rapid DNA tests are critical in early identification of infected individuals in disease outbreaks, and the COVID-19 outbreak will be no different. With the SARS outbreak, it took just two months to contain the disease once a rapid diagnostic was available; however, creating the test was time consuming, taking researchers six months to identify the viral agent and, crucially, its genome sequence. For COVID-19, thanks to the work of researchers in Hong Kong, two rapid tests have already been developed; which was possible due to the similarity of COVID-19 infections to the infections associated with the SARS outbreak, making identification of the viral pathogen easier.
These rapid detection tests rely on a method called real-time reverse transcription PCR, which turns the viral RNA present in a patient sample into DNA and then amplifies it to a detectable level, which allows a diagnosis to be made within a few hours of the sample being taken. This early detection allows for timely deployment of targeted mitigations, which will act to drive down the infection rate of the disease, ease pressure on overwhelmed hospitals by identifying those quarantined for having symptoms like coronavirus but not actually infected, and prevent its spread until the outbreak is halted altogether.
However, conventional rapid DNA tests may struggle to identify patients with very early stage infections where the level of viral RNA present is very low, and so a risk of false negatives and therefore missed diagnoses exists.
In the future this risk may be addressed using technology such as Microgenetics SwiftDetect® which is capable of detecting a single target genome and thereby identifying patients with even very early stage infections. SwiftDetect is a nucleic acid amplification test method, capable of detection of a single target in a large sample volume in under six hours.The test is capable of adaptation to a wide range of sample types and microbiological targets and therefore could play an important role in early detection of a range of diseases which will allow the necessary mitigations and treatments to be administered in the most effective way.