More than a year into the pandemic and the country is reeling under the unforeseen circumstances brought by the second wave of coronavirus. The dearth of hospital beds, inadequate oxygen supply, and fatigue have imbued doubts and fear among citizens. The misbalance in the demand-supply ratio is surely a challenge that has to reach equilibrium soon. However, incomplete recovery or misdiagnosed Covid-19 patients are also the elephants in the room that need to be addressed. Reports have surfaced where patients are complaining of Covid-like symptoms despite testing negative, leading to confusion. To avoid delayed treatment, mishappenings, and confusion, it is vital to understand the reasons and best possible solutions.
SARS-COV-2 Reverse -transcriptase Polymerase chain reaction (RT-PCR) detects viral RNA and a positive result is highly specific for the presence of the virus. The sensitivity of an RT-PCR test in diagnosing Covid-19 varies between 80-90% depending on the proper technique of collection, from where is it collected ( nasopharynx, throat, or both), how well the sample was stored and transported from the collection room to the lab, the platform used and its limit of detection and all this could affect the result. We could get a false negative report despite having symptoms. Getting tested too early or too late could also give a false negative report. The time taken for symptoms onset from exposure could be anywhere between 2-7 days but some people immediately getting tested upon exposure to a positive person. It is best to first self-isolate and gets tested 3-4 days post-exposure. Low viral load (if there are not enough virus particles present for detection) is also one of the reasons due to which result comes back negative. Therefore the interpretation of the RT-PCR test should all be done in conjunction with the clinical symptoms of the patient, lab markers like CRP, D-dimer, and radiological investigations. A negative test could also be repeated if the doctor suggests. Preferably an accredited lab should be chosen and one should not go lab hopping as the assays and cut-offs could majorly vary and cause confusion.
The constant reports of new variants have made it extremely critical to keep a check on genetic mutations of coronavirus as they are a matter of concern. According to the American Food and Drug Administration, false-negative test results can appear due to the genetic variants of SARS-CoV-2 that are routinely generated, So far, the central government has denied such concerns of failure of RT-PCR testing.
RT -PCR test does not distinguish between alive or dead virus and the patients can continue to get a positive RTPCR test for long after they feel fine. It is generally not advisable to get a positive RT-PCR test repeated as false positives are extremely rare and can occur only in case of contamination in the lab or a sample swatch. Such like aberrations are controlled in accredited labs practicing good quality control. The patient usually in mild cases would be fine after isolating for 14-17 days. The virus stops replicating after 10 days. There are now many tests coming in which test for the replication of the virus and they would help allay the fears of the population when they come to realize that the positive RT-PCR is a dead virus.
As the only beacon of hope, the vaccination drive needs to be fast-paced and availability in the population should be enhanced by ramping vaccine production, allowing more vaccines to come into the country, and vaccinating children as a safeguard for avoiding the third wave. Till we develop herd immunity, Covid-appropriate behaviours are the best and only defence against the pandemic. To ensure that gains during our fight against the pandemic aren’t reversed, double masking, social distancing, hand sanitizing, and cleaning of high touch surfaces should be followed. Also, a healthy lifestyle and positive thinking would go a long way in keeping our immune cells fighting fit.
(Dr. Namita Jaggi is the Chairperson, Labs & Infection control, Artemis Hospitals Gurgaon)