Covid-19 is considered to be an infectious virus and the Omicron variant is deemed as even more dangerous when it comes to the rate of spreading. Nevertheless, many people who have symptoms and have remained in close contact with a Covid infected person have tested negative in RT-PCR tests. There can be many reasons for the same. Here are a few to clear your queries –
Sampling Error
One possible reason why your RT-PCT is showing negative results for even those who have classical symptoms is error in sampling. As per Dr Vijay Dutta, Internal Medicine, ESIC hospital, “If the procedure is correct, sampling is taken correctly, if transportation of the sample is at a temperature of 2-5 degrees Celsius, after collecting the sample the RT-PCR will be positive”.
According to Dr Alpana Razdan, VP, microbiologist, Genestrings diagnostics, another reason why the RT-PCR is coming out negative can be - "If the swab hasn't been taken correctly, or there aren't enough viral particles that have been taken on the swab to test for the result."
Time of taking test
In case you are doing sampling at a time when the person is in a state of incubation, or hasn’t developed florid symptomatology yet, then your test results might come out negative. This is because the incubation period reflects the time taken by the virus to develop symptoms after entering the body.
As shared by Dr Rajeev Jayadevan, clinical researcher advising the Covid task force, IMA Kochi, Kerala, “In the case of Omicron, the maximum amount of virus appears after day three of onset of symptoms, till day six. After that, there is a drop. Therefore, on the first day of symptoms, the test might show a negative result”.
Many experts claim that the incubation period can be a little longer too. According to Dr Razdan, the average incubation period is four-six days. The optimal timing to test is six days after the onset of symptoms even though many people could result positive sooner.
Timing of contracting the virus
Many people infected with the Omicron variant are symptomatic. Consequently, they test negative if they have already gone past the infective phase.
As per public health experts, a person can transmit the virus to another person from day one after getting infected till up to 10 days after that. Notably, people are most likely to test positive between 24 hours prior to showing any major symptoms.
Various other factors could also impact the results of Covid-19 tests. A person’s general immunity, age, vaccination status and other comorbidities might impact the onset of symptoms and virus detection.
