People Without Symptoms Can Spread COVID-19—Here’s What That Means

2 min read

COVID-19 is capable of presenting itself asymptotically, which only exasperates the anxiety most people might be feeling. However, to understand how a virus works, we need to understand a little epidemiology. So here we go, but first, some definitions:

The incubation period – The period between exposure and showing signs or symptoms of the infection. It is primarily related to the biology of the interactions between hosts and pathogens. For example, how quickly the host mounts an immune response to clear the pathogen.

The latent period – The period between exposure and becoming infectious. The ability to spread the disease to others and is partly related to disease dynamics, including social network interactions.

When the latent period is shorter than the incubation period, it can present a challenge to epidemic management since asymptomatic patients can spread the disease. The success of reactive disease control strategies has shown to depend on the timing of the onset of infectiousness relative to the start of detectable clinical symptoms. 

Now, what do we know about the COVID-19 incubation and latency periods? Like everything else related to COVID-19, which has scientists worldwide scrambling to understand it from nearly every vantage point, we cannot yet be 100% sure.

A study of 52 Chinese patients found the incubation period to average 5 days, with a typical range of 2–14 days. Such studies agree with the general recommendation of a 14-day quarantine period, to be sure a person is not infected, whether symptomatic or not.

The likely existence of asymptomatic transmission of SARS-CoV-2 causing COVID-19 does NOT mean we should not bother to test patients and ask them to self-isolate. Isolating carriers and patients are still essential!

It is wise to detect and sequester patients by offering widespread free testing using real-time (rRT-PCR) detection of the SARS-CoV-2 virus and by conducting fever checks which, is much easier for screening.