You might have just tested Negative for Covid-19 and maybe thanking God for this. In that case, you may need to take a step back as the report might not actually be giving the true result. As per a new study, testing for Covid-19 at a too early stage of infection may lead to a false-negative result, even though you might be infected. Based on the study it is best to perform the test atleast 3 days after you start to develop symptoms.
Lauren Kucirka, a co-author of the study from Johns Hopkins University said, “A negative test whether or not a person has symptoms, doesn’t guarantee that they aren’t infected by the virus.” Also she said that “How we respond to and interpret, a negative test is very important because we place others at risk when we assume the test is perfect. However, those infected with the virus are still able to potentially spread the virus.
According to scientists, patients who have a high-exposure should be treated as if they are infected, particularly if they have symptoms consistent with Covid-19 and they believe that patients must be informed about the shortcomings of the tests.
Also, the scientists said that how RT-PCR tests may yield a false-negative result when a swab misses collecting cells infected with the virus, or if virus levels are very low early during the infection, some tests can produce negative results. However, they said the tests return relatively rapid results, due to which they have been widely used among high-risk populations such as hospitalized patients, home residents, nursing, and health care workers.
Meanwhile, in the current analysis, using RT-PCR test results, along with the reported time of measurable symptoms such as fever and breathing problems, the researchers calculated the probability that someone infected with SARS-CoV-2 would have a negative test result at the time of infection. Besides this, the researchers estimated that those tested with SARS-CoV0-2 in the four days after infection were 67% more likely to test negative, even if they had the virus.
According to the experimenter, the test performed best eight days after infection, which on average is three days after symptom onset and even then, they said the test had a false negative rate of 20 per cent, which means one in five people who had the virus had negative test results.
The sooner people can be accurately tested and isolated from others, the better we can control the spread of the coronavirus, the scientists said.