As reports of COVID-19 surge is causing a flutter across the globe, including India, how we test, track, and genome sequence play a key role, say experts.
So, how likely is it that your at-home Rapid Antigen Test (RAT) shows a positive result? What mistakes should you avoid while using one? Here's all you need to know.
Can RAT detect Omicron subvariants?
Yes, but there is also a possibility that it may not detect the subvariant, unlike the RT-PCR test.
According to the US Food and Drug Administration, antigen tests — more commonly known as at-home tests — "are generally less sensitive compared to molecular tests (PCR tests), especially regarding early infections. This sensitivity may decrease further, due to the genetic changes in the virus over time."
But, why is this?
RATs work by detecting specific viral proteins – which help detect COVID infection. But as virus evolves, the viral proteins also tend to alter – and experts say, that this can affect the ability of the test to detect COVID-19.
This means that the RATs cannot pick smaller amounts of virus in the body, says Bruce Tromberg, PhD, director of the National Institute of Biomedical Imaging and Bioengineering:
"If you have an early stage of your infection, with just a little bit of virus inside you, the antigen test isn't going to pick it up. You may get a negative [result] one day and then 12 hours later—because [of] the way that the virus is expanding so fast in your body—you could get a positive."
According to Marc Sala, co-director of the Northwestern Medicine Comprehensive COVID Center, prior to COVID vaccines and variants, the RAT tests showed 95 percent of the results to be positives, reported Axios. But this changed.
But with Omicron – with a significant population being vaccinated and asymptomatic – this sensitivity may just be 25 percent, Sala said.
Since the RAT may not be able to pick up low amounts of virus, it is likely to throw a negative result for people who have better immunity, and have taken their booster.
What do we know about RATs in India?
There is no specific information on whether RATs available in India can detect Omicron sub variants.
The kit is manufactured by Tata Medical and Diagnostics named OmiSure and MyLab's CoviSelf have claimed that they can detect variants of Omicron.
What should I do if I test negative on RAT, but still have COVID symptoms?
In such cases, multiple experts have told FIT, that a RT-PCR is advised if someone is showing symptoms of COVID, but is repeatedly testing negative on an at-home test.
What should not be done while using home-test ideas?
Storing at the wrong temperature
Using straight from the fridge
Taking the test too soon or too late after exposure
Contaminating the test by touching the swab
Eating, drinking, chewing gum, brushing your teeth or smoking before a saliva test
Reading the result too early or too late