Rapid COVID19 testing: Will at-home kits allow a return to normality?
A quick test to rule out the coronavirus before a party, or to check the risk of infection in the office: Newly developed rapid tests could allow for at-home testing for Covid-19. Read More
A new school of testing is developing in the USA: Instead of carrying out expensive and drawn-out laboratory testing, many scientists and entrepreneurs feel people should be tested more frequently using less sensitive assays. Rapid tests could allow for at-home testing, pursuing one central goal: to return to life as we once knew it as soon as possible.
It is a simple and revealing thought experiment: if every single person could test themselves for the Sars-CoV-2 virus in the comfort of their bathroom or on the sofa, wouldn’t that lead to the wide-spread control of the tricky virus? Imagine you could test yourself daily or at least a few times a week before heading to the office, bringing the little ones to daycare, going to the theatre or attending your best friend’s wedding.
A quick check that would become as routine as brushing your teeth: a bit of spit on a test strip, wait a few minutes, and then another negative result means you can get on with your day. Or it comes up positive, so you know it’s time to call the doctor and quarantine immediately.
We are not there yet though. When someone undergoes a coronavirus test today, it is usually because they have developed initial symptoms or gone to see their doctor about a fever and a cough. If it turns out to be Covid-19, then the carrier has already been contagious for a number of days and may have infected a whole host of other people. So, we are always a few steps behind the virus as it continues to spread, making it almost impossible to get the pandemic under control, according to epidemiologist Dr. Michael Mina from Harvard University.
Mina has frequently been quoted in the media warning the public about another serious issue. In the USA, many people do not test positive for the covidvirus until after they have almost completely recovered. Their tests still come up positive because the standard polymerase chain reaction tests (PCR) done in laboratories react to tiny remnants of the virus, even if the viral load is no longer enough to infect other people. Mina is not the only one raising the alarm that this renders the infection rates calculated based on diagnostic testing in the USA worthless and even misleading. And, he told the New York Times, the testing being done is clogging up the entire process chain. People have to wait days for test results and longer waiting times drive up a sense of insecurity and the risk of infection.
A quick check that would become as routine as brushing your teeth: a bit of spit on a test strip and you can get on with your day.
A paper strip instead of lab equipment
There is good news though too. The kind of test Mina is calling for – at-home kits that yield fast results similar to blood sugar and pregnancy tests, are already available. And at one dollar a pop, they are comparatively inexpensive to produce and sell.
Laboratories like E25Bio have been working on developing a reliable test. Founded in 2018 at the Massachusetts Institute for Technology (MIT), E25Bio specializes in at-home tests for active dengue, zika and the chikungunya virus.
When the Sars-CoV-2 pandemic hit, the company focused all its efforts on the novel virus. “Infectious disease surveillance should prioritize affordability, accessibility, and sample-to-result time, especially during outbreak scenarios such as the COVID-19 pandemic,” Dr. Bobby Brooke Herrera, co-founder and CEO of E25Bio, said in spring 2020.
Users simply swap their nose with the paper strip, place it the vial with the liquid, close the top and wait 15 minutes.
While the molecular PCR protocol tests a sample for the virus’ RNA – a complicated process only possible in a laboratory – the rapid testing process developed by E25Bio looks for antigens to the virus. These are surface proteins the virus uses to invade the cells of the human body. The test kit consists of little more than a paper strip, a small, plastic vial and a bit of testing fluid. It could not be easier to use either. Users simply swap their nose with the paper strip, place it the vial with the liquid, close the top and wait 15 minutes. Then the appearance of one or two bands tells them their infection status.
“Less sensitive and more often is better than highly accurate and less frequent”
Rapid tests have been the subject of lots of criticism though, in particular because they are not as accurate as conventional PCR tests. They can only respond to a higher viral load than the extremely sensitive PCR lab tests. This opens up the possibility that infected people – who might be contagious – test negative for the virus, and feel safe to go out in public and possibly spread the virus further.
As of April 2020, the WHO was still advising against using direct antigen rapid tests (DART) outside of research settings. In a statement, the health organization argued that “half or more of COVID-19 infected patients might be missed by such tests,” adding that the data available was still too limited. The US Centers for Disease Control and Prevention (CDC) also qualified its DART recommendations: “Rapid antigen tests perform best when the person is tested in the early stages of infection with SARS-CoV-2 when viral load is generally highest.”
The agency added that while DART provided useful information, there simply is not enough data yet to say with certainty whether they could be used for preventative screening of asymptomatic individuals.
Harvard scientist Mina rejects these misgivings and sees the fact that antigen tests only react to high viral loads as an advantage. Mina argues that while the PCR test can better detect the virus, the results provide no information about whether the virus is still active or whether the test might just be reacting to small, harmless residue of the virus’ RNA. This would mean “millions of people” would have to go into quarantine although they had already recovered from the infection, which is not, Mina says, a problem with the less sensitive rapid tests. Used properly – comprehensively and frequently – DART would allow us to identify of the narrow but dangerous time period when people are infectious.
Other scientists like Dr. Paul Sax, a professor of medicine who runs the Infectious Disease Clinic at Brigham and Women’s Hospital in Boston and teaches at Harvard, support Mina’s position. Sax agrees that screening tests do not need to have PCR-level sensitivity. “Better strategy: frequent, cheap, rapid, LESS sensitive test,” he tweeted, before adding “a widely available, rapid and inexpensive test for COVID-19 could be very valuable in low pre-test probability cases.” The WHO has not entirely dismissed the usefulness of rapid testing either. While it does not currently recommend the use of antigen-detecting rapid diagnostic test for patient care, the organization strongly encourages research into their performance and potential diagnostic utility.
The overriding goal: return to normal life
Companies and developers like E25Bio are encouraged by such positive, if tentative, responses. While they wait for a final decision from the Food and Drug Administration (FDA) and permission to go to market, the first tests are making the rounds. They are being used in hospitals and in LabCentral in Cambridge, a biotech incubator at MIT where volunteers have been able to try out free on-site-testing with the new rapid test as of mid-September. LabCentral’s founder, Dr. Johannes Frühauf, is optimistic: if everything goes well, he said on Twitter, “These types of tests (will) allow a return to normal life quickly.“