Coronavirus symptoms: Why a negative test may not mean you are safe from COVID-19

Getting tested for COVID-19 is one of the ways to safeguard yourself and your close contacts from the virus. But what if you were told that a negative test may not entirely mean you aren't infected by COVID-19 or that you are safe from it. We explain why

COVID-19 tests are usually in the form of antigen tests, or the more reliable or accurate, RT-PCR tests, which are considered to be the gold standard right now.

While antigen tests detect antibodies using a blood sample, a diagnostic test like RT-PCR test studies the viral DNA/RNA of the molecule by using a polymerase chain reaction. This is usually done by performing a number of cycles, which determines the CT value.

Even though there are a lot of theories which suggest that CT value could indicate the contagiousness or spread of infection, it is only a numeric count that determines a rough value of viral load in the body. Right now, considering the variety of tests available in the market, no two diagnostic tests will have the same meaning for the CT count, meaning, there is room for wrong results.

A negative result comes up when a diagnostic test isn't able to detect sizeable load after repeated cycle testing in a given time (24-48 hours post sample collection and testing). On the other hand, even if the test picks up a fragment of the virus, it means the person is positive for coronavirus.

The one thing we should know is that no one test is 100% accurate, or sensitive right now.

As much of a reassurance a negative COVID-19 test can be, experts believe that taking the tests lightly, or 'interpreting' the results wrongly can make matters worse.

Antigen tests, of all, have the biggest failure rates- and can show up inaccurate or false results. Sometimes, people who test negative for COVID-19 on an antigen test are asked to go for a repeat test to confirm results. With RT-PCR tests, the risk might be rare but still exists.

Secondly, a negative COVID result can also come up if the body doesn't detect sufficient viral load in repeated cycles. This can also happen when a test is administered inaccurately.

Diagnostic errors and lapses can also lead to wrong results. According to experts, right now, during the pandemic, false-negative rates could be as high as 30%.

SARS-COV-2 has an incubation time of 5-12 days. Sometimes, it can take longer. If a person gets tested too early post exposure, there are chances of the test coming out negative, as the virus may not be actively replicating, or develop in the body needed for testing.

Worse, studies have shown that the virus can still transmit from one person to another even if there isn't a conclusive viral load.

Not really. According to studies, the chances of getting a false negative are at the highest for people who get tested during the four days before symptoms start.

If you probably have been exposed to the virus or a COVID+ person, it's best if you wait out for a while (5-6 days), watch for your symptoms and then go for testing.

There's another judgment people make post a negative diagnosis- that they are immune from the virus and cannot spread it to others. This could be one of the biggest mistakes which could put you at risk. A negative result may mean that you are not infectious, but still are at a risk for COVID-19. No matter the diagnosis, a person should be practising quarantine for a while before mingling with other people. That is why one should not be gaining a false sense of security after testing negative for the virus.

So, while widescale testing is one of the ways we can detect cases and break the chain, self-isolating, following safety measures is one of the best and reliable measures to fight the risk of COVID-19.