The COVID-19 pandemic has disrupted the lives of billions of people, nearly overwhelming healthcare systems and pushing the global economy to the brink of collapse. The quest for effective treatments and a preventive vaccine starts with – and depends on – the broad availability of fast, accurate and reliable diagnostic tests.
The number of people known to have been infected worldwide with SARS-CoV-2 has soared past five million and claimed the lives of more than 350,000 and the number of known cases continues to rise. In Canada, there has been more than 86,000 confirmed cases of COVID-19 and 6,600 of them died from it.1 So far, the United States has had the greatest number of confirmed cases − and deaths – exceeding even the toll in China where the disease originated. However, public health experts have voiced their concern that the current number of both cases and deaths is inaccurate because too few people have been tested. While the virus is deadly for some, causing pneumonia, severe acute respiratory syndrome or kidney failure, many who have it experience mild symptoms or no symptoms at all, making it much harder to detect and contain.
In every country affected by the pandemic, experts have come to recognize one indisputable fact: diagnostic testing is critical to containing and controlling this global health threat. Along with measures like social distancing and self-isolation, high-quality testing is an essential part of the response to the COVID-19 pandemic, which currently has no approved vaccine or disease-specific treatment. Two criteria are paramount to broad testing programmes for SARS-CoV-2: high throughput, meaning that laboratories can test a high number of samples in a short time frame, and accuracy, which means a reliable test result. In Canada, Roche Diagnostics has collaborated closely with health system authorities to ensure that tests are reviewed and made available to as many people as possible.
SARS-CoV-2: the right test at the right time
Currently, there are two types of tests providing the most essential information about infection with SARS-CoV-2: 1) a polymerase chain reaction (PCR) test based on a patient’s nasal or throat swab (also known as molecular test) and 2) an antibody test based on a blood sample (also known as serology test).
Why antibody tests are so important
Molecular tests are used to identify people with ongoing or active SARS-CoV-2 infection and confirm the diagnosis of COVID-19. Typically, this type of testing is restricted to people with symptoms such as fever, cough and breathing difficulties. Since an infection with the virus may occur without symptoms, many people may not be aware that they have already been infected with SARS-CoV-2. Therefore, a high number of unreported cases is assumed, and antibody tests may help provide clarity on this. Antibody tests are used to determine whether a person has been previously exposed to or infected by the virus (podcast). When someone is infected by the virus, their body will react to the infection by producing specific antibodies against that virus, and this is what antibody tests detect. This typically occurs in the weeks that follows the infection, as the patient recovers. Currently, the scientific community does not know if the antibodies that are generated as a result of SARS-CoV-2 infection are able to confer protective immunity (i.e. whether they are able to protect against re-infection by the virus) and if so, for how long this immunity might last.
Success depends on collaboration
Broad access to reliable COVID-19 testing is essential to accurately identify who is infected and to contain the disease. “All countries must aim to stop transmission and prevent the spread of COVID-19,” said Dr. Tedros Adhanom Ghebreyesus, WHO Director-General.2
As healthcare professionals and regulatory authorities gain more knowledge about the disease, lessons have emerged that can be applied to future disease outbreaks. Infectious diseases don’t respect national boundaries − everyone needs to work together to understand, contain and treat the outbreaks. Information needs to be shared early and freely. And importantly, accurate and reliable diagnostic tests are essential to determining the extent of the outbreak and to protect those most vulnerable. “You can’t fight a virus if you don’t know where it is. That means robust surveillance to find, isolate, test and treat every case, to break the chains of transmission,” Dr. Tedros said.
References
1. Worldometer. Coronavirus cases and deaths. [Internet: Cited 2020 May 26]. https://www.worldometers.info/coronavirus/
2. World Health Organization. Mission Briefing on COVID-19: WHO Director-General’s Opening Remarks. [Internet; cited 2020 Mar 12]. Available from: https://www.who.int/dg/speeches/detail/who-director-general-s-opening-remarks-at-the-mission-briefing-on-covid-19---12-march-2020