Rapid test kit for Covid-19 could be as dangerous as the virus

Areport goes out every Tuesday from the Nigeria Centre for Disease Control, providing updates on a handful of infectious diseases the country continues to battle—measles, Lassa fever, meningitis, cholera.

February 27 came with the first confirmed case of coronavirus in the country, which causes Covid-19. Since then Covid-19 has squeezed into a slot among infectious diseases the centre is watching, and the infections have risen to threedigit figures in just over a month.

It has neither a cure nor a vaccine. Its symptoms were much publicised, but difficult to tell from the regular headache, fever and cough. No one knew who had it until it was too late. Containment mode was activated and the World Health Organisation ( WHO) screamed, “Test, test, test.”

A flurry of requests for tests poured out. Anyone who had shared space with the first few confirmed cases or felt any of the now-known symptoms wanted to get tested just to be sure.

High-profile names ranging from governors to celebs got on the queue faster than anyone else, Nigerians thought, sparking notions the testing was targeted.

But the NCDC network had only five then now seven molecular labs capable of the level of testing required. It issued guidelines on who should be tested and when.

An Instagram post of Nollywood actress Tonto Dikeh getting a mouth swab ignited more them-versus-us comments, and now it is moving dangerously close to do-it-yourself using a rapid test kit.

NCDC has said no, and there are no recommended rapid test kits for coronavirus for the simple reason that their accuracy has not been determined.

“We are aware of validation studies going on. Until these are completed, we cannot procure rapid test kits, because we do not know if they work,” the centre said in response to calls for it to procure kits.

Secretive internet sites have on offer self-test kits that look attractive to anyone who doesn’t want to wait for the bureaucracy of a lab test. One is the Covid-19 1gM/1gG Antibody Rapid Test, which instructs individuals to take samples of blood and then add three drops of a diluting agent for a 15-minute incubation to see the results.

When you get infected, your body mounts a response to fight the infection. This process creates antibodies. When serological tests detect these antibodies, it is a sign that you have been exposed or have fought an infection or even become immune. (As the novel coronavirus has never emerged in humans, there has been no time to build immunity).

A second type of test doesn’t detect the antibodies but the antigen itself, the infective agent that caused the infection in this case, coronavirus.

Therein lies the rub. Antibodies can be detected even after a person has been cured. And some people are not able to mount enough response to produce antibodies to be detected even when the pathogen is present.

The College of Nigerian Pathologists has raised concern about adverts for rapid test kits for Covid-19, and worried some people were already showing interest.

“In the first instance, many of these kits are antibody-based and may not be appropriate for accurate diagnosis,” said Dr Philip Olatunji, president of the college.

“Secondly, they are not validated, hence their sensitivity and specificity are unknown.”

The antibody-based tests are said to produce a positive result in five minutes, and negative in 13 minutes.

“The #COVID19 test reagents which Nigeria has received & procured recently can only be used for PCR tests in existing molecular laboratories There have been important developments such as use of Gene-Xpert machines. We’re also expanding our testing capacity using this technology,” said NCDC.

But a lab-based test takes hours. Called “polymerase chain reaction” it works on the premise that there is already a genetic sequence of the coronavirus. NCDC successfully sequenced the virus gene and shared with WHO.

So, a test starts with taking a mouth or throat swap. The swab is put through a reagent to break up the virus and compare it against the sequence already in the database.

Last week, the Nigeria Institute for Medical Research setup a drive-in testing centre to help ramp up test numbers—along with an online selffill form to collect health information of potential test subjects.

For mass testing, the country would have to ramp up capacity to test thousands daily.

Calls have been made to decentralise so teaching hospitals able to run tests can step in— as well as private labs that have the capacity—in order to meet up.

Which is why a kit you can use like a simple pregnancy strip test sounds brilliant. But it isn’t, when you consider the implication of using kits that cannot detect coronavirus but detects antibodies. And it is also why the #takeresponsibility campaign matters.

“Somebody who is already cured but still having antibodies, it will say they are positive when they are not,” says Olatunji.

“Secondly, the process of the virus is very important. There are some people who may not be able to mount a response that will produce antibodies. If you are not looking for the virus itself.”