Concerns have been raised around so-called false-negative Covid-19 test results, now this is when people test negative for COVID-19 only to test positive a few days later. Experts are saying that laboratory tests on potential covid19 patients are sometimes carried out before the virus takes hold in a person’s respiratory tract and therefore can go undetected. Researchers at John Hopkins University said the likelihood of testing negative of COVID19, 4 days of the exposure to the virus is as high as 67%, so the question then becomes when is the right time for one to get tested and how sure can one be that-in fact the art of so-called-danger zone when the test comes negative. The seemingly shifting goalposts in coronavirus are the subject need to be discussed. 65% of the symptomatic patients who had tested negative for Covid-19 in antigen test are being confirmed later as positive in RT-PCR testing, shows the report from minor civic laboratories in Mumbai. Stated like Maharashtra are now treating initial positivity rate with increasing suspiciousness as a high number if negative results in antigen tests are now turning to be a false negative. This is now turning Tamil Nadu to rely exclusively on the real-time PCR test. But one good thing that has happened is with the same methods Delhi has seen a significant success rate. The reports suggest that between June 18 and July 21, patients who were tested as negative we’re confirmed positive for COVID increasing the fear of false-negative cases.
“We have an adequate supply of RT-PCR kits and the facilities to run the test. So, we decided to stick to the most reliable test,” state health secretary J Radhakrishnan said. Because of these antibody tests giving too much wrong false negative, Tamil Nadu has cautiously opted RT-PCR and this has helped them minimize the flaw and helps in getting accurate results.
Why does false-negative occur in the first place?
The time when one receives a negative COVID-19 test depends on why and when you go and what the reason is for having the test in the first place. If one has had contact with someone that is positive and if you are still asymptomatic but you had significant contact with the person there’s no point in having that risk immediately because there’s a period of time before somebody is going to be having the virus in the respiratory tract so the incubation period of the infection is anything up to 14 days but it’s actually closer to about five days. Usually the first five to seven days, the person will be feeling perfectly fine and there’s no point in testing at that time. The test becomes positive just before symptoms start developing so that would be about a day before you first start developing the malign and the feeling unwell because that is when the virus spikes and peaks in the respiratory tract and this would be the time you have the highest likelihood of getting a positive result. After the first week of that illness, the virus levels drop off gradually as your body develops the antibody immune response to the virus. Hence, the highest chance of people detecting the virus is the first day of the symptom. The knee-jerk reaction is to go immediately for a test once you’ve learned that you’ve been in contact with someone who’s actually contacted the virus which is actually a complete waste because the outcome there is in some instances unlikely to be accurate. The advice to somebody who’s had a significant contact is that they should isolate themselves because they don’t know when they’re going to be sick. All we know is that the average is 5 days but we don’t know that surely for it can be more than that or less than that.
COVID-19 has put us in a unique situation that we are developing tests and treatments as we’re learning about the disease as we are treating the disease. Hence we don’t have the luxury of time as other illnesses where we have tried and true methods are a developing question. To make matters even more complicated there are other coronaviruses around. The common cold is a coronavirus, so some of the antibody tests are unfortunately cross-reacting with either coronavirus as well and the high false-negative rated are making it very challenging to determine who has it, who doesn’t have it and some has the opposite problem, some people it has a false sense of security that they had it when that may not have. The health minister keeps giving us tons of information regarding the testing but a definite number or figure for how many are false negative is not done. That information is not captured anywhere so we don’t know how many people are having a wrong test, all we know is what comes into the laboratory and then the proportion of them that comes out as positive. In more regulated areas like the healthcare environment, people know exactly when the right time to have a test but when it’s outside of your control you don’t really know that information and it’s not captured.
A negative test doesn’t guarantee you that aren’t infected with the virus. A lot depends on when exactly you are tested. Doing it too soon can give you a false negative and this has big implications as we open up the economy. New research suggests that more people could be walking around sick than we thing, showing that the main type of coronavirus testing produces at least one in five false negatives. On infection day a test is completely ineffective, by day five when symptoms typically start the false-negative hits 38 percent drops to 20 percent by day 8 before climbing back up. These kinds of these shows that we are missing some important parts and not that the person is free from virus. Neurologists are saying that there is so much unknown about the COVID-19 and there are so many variables until we can find a better-standardized test, people should get tested more than once. Coupled with false-negative- the mystery of asymptomatic transmission- the World Health Organization forced to walk back comments that asymptomatic people posed little to no risk, now saying the science isn’t settled. They are out there and we cannot detect them and they don’t know they are infected. There might represent an important element in this printing of the virus. Keeping all this in mind as provinces take more reopening steps but experts say it shouldn’t stop people from living more normal lives.