Rapid COVID-19 tests: how good are they?

The COVID-19 pandemic marked the first time in the history of pandemics that self-testing was used as an essential part of a broad public infection control and prevention strategy. Nearly four years into the pandemic, study highlights diagnostic accuracy and impact of SARS-CoV-2 antigen rapid diagnostic tests used for COVID-19 self-testing .

The study, led by Dr. Nitika Pant Pai of the Research Institute of the McGill University Health Center (RI-MUHC) and published this week in the journal PLOS Global Public Healthsuggests that the value of self-testing lies in rapid identification and isolation of highly contagious individuals and that certain aspects of the self-testing strategy may improve self-testing performance, such as clear instructions for use and d interpretation of results, as well as adequate pre-test training. .

“Overall, the results of our study are impressive. Evidence shows that self-testing is an effective tool for preventing transmission of SARS-COV-2 and suggests that it has helped control outbreaks and limit transmission, and has enabled work to continue during the pandemic.

“Going forward, public health agencies and governments should not hesitate to invest in accurate, rapid, portable and perhaps digitally enhanced self-testing strategies, such as apps, websites and video instructions, not only for respiratory viruses but also for non-respiratory pathogens,” says study lead author Dr. Pant Pai, a scientist in the Global Health Infectious Diseases and Immunity Program at the Center for Research and of results evaluation of the IR-MUHC and associate professor of medicine at McGill University.

The study consists of a living systematic review, meaning it will be updated in a year, and a meta-analysis of 70 studies – with pooled data from 25 countries – that assessed the diagnostic accuracy of rapid tests for COVID-19. The authors analyzed the data based on a number of different variables, such as collection site, symptomatic state, supervised/unsupervised self-testing method, and presence/absence of digital support.

The researchers also examined the feasibility, acceptability and impact of self-testing, as well as people’s preferences and motivations, as well as the main facilitators and barriers to adopting the self-testing strategy.

An effective, feasible and acceptable preventive strategy

According to the study results, rapid tests for COVID-19 have very high specificity (ability to detect negative cases/healthy individuals), with a proportion of true negatives consistently above 98%. Most of the false negative test results reported in the study occurred when the person was less contagious and outside the window of transmissibility.

The sensitivity of the test (the ability to detect positive cases/infected individuals) differed between subgroups, depending on the variable studied, and was consistently low in asymptomatic individuals (the test did not not detected the infection in them) but high in symptomatic individuals (the test did not detect the infection in them). failure to detect infection).

The highest sensitivities, or highest truly positive proportions, were observed among groups of people who:

• completed their test in a supervised environment (86.7%),
• were symptomatic (73.9%)
• used nasal samples from the middle turbinate, that is, a sample taken just higher up the nostrils inside the nose (77.8%)
• used digital support strategies such as apps, websites, and video instructions to improve testing delivery (70%).

Additionally, researchers found that users had a strong preference for COVID self-tests and were willing to use them, but their interest in repeated or daily use was low.

More importantly, the results have been numerous: self-testing strategies have not only led to fewer school closures and workday savings for essential workers, they have also prevented the transmission of infection among health workers, facilitated the continuation of work in health laboratory sites and enabled social activities. continue their activities with a lower risk of infection. These results highlight their significant impact on public health.

Finally, the authors point out that pre-training sessions, detailed self-testing instructions in plain language, and special test kits designed for low-literacy, rural, peri-urban, and elderly populations could further improve performance and adoption of self-testing by these populations.

“Equitable access to COVID-19 self-testing will empower individuals and remove barriers, paving the way for a healthier and more inclusive society. The pandemic highlights the need for increased research into such innovative diagnostic approaches,” says Apoorva Anand, first author of the study and intern of Dr. Pant Pai at the IR-MUHC.

“COVID self-tests have helped democratize access to self-tests and normalize conversations about their use in homes, workplaces, offices and gatherings. The self-testing strategy is now here to stay, not only during pandemics, but as a strategy to control other infectious and non-infectious diseases and conditions.

“We need to provide high-quality self-tests to maintain public confidence in the self-testing process and encourage individuals and communities to proactively use them for their own benefit,” adds Dr Pant Pai, recognized as an expert world leader in diagnostics on self-testing and point-of-care testing technologies.