Rapid Tests Unmasked: Why Your COVID-19 Results Might Be Playing Hide and Seek!

Negative Covid-19 antigen test kit, one step coronavirus antigen rapid test, saliva swab, 1 test box with imagine of lungs, close up

For the fifth year in a row, COVID-19 has brought various concerning factors along with it since its first appearance in 2019.

In the early 2020s, taking a COVID test was quite difficult, but today, the abundance of cheaper rapid kits in grocery shops and home medicine cabinets has led to a new concern: they do not seem to work!

The concern was shared by the immunologist and epidemiologist Michael Mina, who said, “When people tell me that their rapid antigen tests never turn positive, they’re usually talking to me because they’re frustrated,” the Strait Times reported.

Why don’t the tests seem to work now?

The tests just work as well as they did when they first came out. What has changed is how our bodies are responding to the coronavirus, leading many people to test too early, said Dr Mina, chief science officer at digital healthcare company eMed. The company, eMed, helped implement the United States government’s Home Test to Treat program a year ago.

In 2020, the loss of smell and taste, fatigue, and a dry cough signaled the start of COVID-19, which used to begin usually a week after the virus entered the body.

Dr. Mina added, “Those first symptoms came on after the virus was tearing you apart,” as per the Strait Times report.

Boosted immunity

With an adequate shield of immunity, the body responds to Sars-CoV-2 faster and more effectively than before, when the virus spawned dozens of new variants.

In this regard, Dr. Mina stated that nasal congestion, fever, and other early signs of viral illness can develop within a day or two of contracting the infection during a “prodromal phase” that occurs before symptoms of the disease have fully developed.

Some scientists even believe that the faster immune system response has led to a shortened coronavirus incubation period.

In 2020, the health authorities recommended waiting four or five days after a coronavirus exposure to get tested, reflecting when the amount of virus in the upper airway was nearing a peak and readily detectable.

Therefore, the experts have outlined that the onset of prodromal symptoms and the relative ease of home testing now mean people are screening for COVID-19 much sooner, as per the reports by the Strait Times.

Tests and spreading the virus pattern

Dr Mina, who is a former assistant professor of epidemiology, immunology, and infectious diseases at Harvard’s T.H. Chan School of Public Health in Boston, said, “A lot of people are reaching for those tests 24 to 48 hours (after) exposure,” and added further, And, just like in 2020, the virus hasn’t yet grown to high levels in the nose. It really takes four, five, six days.”

The ‘educated’ immune systems are providing a kind of built-in rapid test. Instead of a positive result on a test strip, the signal of infection comes in the form of congestion and fever, as per the Strait Times report.

Therefore, Dr Mina added, “You might have to wait an extra day or two before you can run that confirmatory rapid antigen test after your ‘immune test’ has already started to signal that there’s something there.”

According to Dr Mina, “Could you infect your spouse or somebody you’re really close with on day two? Probably,” but “are you likely to be a super spreader and be negative on a test? Probably not.” It means testing positive signals the presence of a lot of viruses and the risk of infecting others.

Which site is better for the COVID test?

Since virus levels across both sites can vary from person to person, Dr Mina recommended swabbing both the throat and the mouth to improve the sensitivity of a rapid test, as per the Strait Times.

The coronavirus survives best at 37 degrees C, therefore making the throat a more hospitable environment than the nose.

Dr Mina said even when someone has mild symptoms after a coronavirus exposure and continues to return negative rapid tests over several days, it does not necessarily mean they have escaped infection or that their swabbing technique or tests are faulty.

It could instead mean that the person’s “educated” immune system has successfully prevented the virus from reaching levels detectable on a rapid antigen test, the Strait Times reported.

According to Dr. Mina, the threshold is about 100,000 copies per milliliter – a tiny fraction of the one billion to one trillion copies per milliliter individuals can have at their infectious peak.

Even if people get Covid-19 and feel unwell, more people will likely not return a positive rapid test as their immunity builds.

Dr Mina added, “I want every test to be falsely negative because that describes the triumph of immunity,” and said further, “It means your immune system is doing what it should be doing.”

Dr Mina cautioned that even when the virus is suppressed in the respiratory tract, it could flourish elsewhere in the body, like the gastrointestinal (GI) tract.

He said, “If you really think you’ve been exposed, and you feel like you have GI symptoms, treatment might be right for you – it might make sense to get Paxlovid even though you don’t have a positive test” and said further, “The test is only as good as the sample, which is only as good as where the virus is in your body,” the Strait Times reported.