In a dense field, the novel coronavirus’s incubation period is one of its most puzzling characteristics.
It has been theorized that carriers shed the most viral debris—and are thus the most contagious, before the onset of symptoms. Unfortunately, there are many factors that determine an infected individual’s risk to the public.
The authors found that patients are generally the most contagious between day one and day five after symptoms begin. This was determined to be true even among those who contracted mild manifestations of COVID-19. Additionally, none of the study samples featured in the report evidenced viral material nine days after the development of symptoms.
“Viral load kinetics and duration of viral shedding are important determinants for disease transmission. We aimed to characterise viral load dynamics, duration of viral RNA shedding, and viable virus shedding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in various body fluids, and to compare SARS-CoV-2, SARS-CoV, and Middle East respiratory syndrome coronavirus (MERS-CoV) viral dynamics,” the authors wrote. We investigated three things: viral load (how the amount of the virus in the body changes throughout infection), viral shedding (the length of time someone sheds viral genetic material, which does not necessarily mean a person is infectious), and isolation of the live virus (a better indicator of a person’s infectiousness, as the live virus is isolated and tested to see if it can replicate in the laboratory).”
According to the authors, viral load peaks in the throat and nose of most infected carriers.
Followup metanalysis confirmed the projections indexed above. An independently conducted contact tracing study out of Taiwan and another one conducted in the UK concluded that the vast majority of samples got infected when they were exposed to an infected person within five days of their symptom onset.
Because early viral load peaks so early during infection, the authors are urging those experiencing instrucive COVID-19 symptoms to self-isolate as soon as symptoms start without waiting for test results.
“Although some people, especially those with severe illness or with a weakened immune system (say from chemotherapy), may have longer viral shedding, the results suggest that those infected with SARS-CoV-2 are most likely to be highly infectious a few days before symptoms start and the following five days,” the authors concluded.