Something I never understood:

  • Does "asymptomatic" mean that someone will never show symptoms whether they catch the disease and therefore, can have without even realizing?
  • Does it mean that they won't show symptoms while they have the disease (during the incubation period) and therefore showing symptoms (after the incubation period)?
  • Or does it mean that they won't show symptoms while they have the disease (during the incubation period), but they never finish the incubation period getting the disease itself and, therefore, not realizing they had it?

2 Answers 2


With a virus, there are 2 separate things that happen at different speeds, and not at the same time:

  • Live virus comes in contact with your body, and starts replicating, and your body is emitting copies of the live virus in exhalation etc. You are contagious and can spread it to other people at this point.
  • The virus starts damaging the body badly enough to do harm, or to provoke an immune system response that itself makes you feel ill. You know you are sick at this point.

These things are separate, and can run on totally different timelines, or may not happen at all, depending on the virus and the person. When a person has the disease (#1) but does not feel the effects of illness (#2), that is called "asymptomatic". You can be asymptomatic temporarily, which is what happens to almost everyone with COVID-19. Or, what happened for Typhoid Mary, you can be at #1 forever without any #2, so you never know you have it! That is called being a "carrier".

On a well-behaved virus, the two will happen about the same time, so a person will feel ill and go into seclusion to protect themselves and others.

On a more dangerous virus, the time lag between #1 and #2 is quite long, and/or some people experience mild #2 effects which they mistake for normal stress/tiredness/side effects of a drug they take for something else. Then, you have a perfect storm for a disease that spreads widely, because you have a lot of unwitting "carriers", at least temporarily.


Asymptomatic refers to a state of no symptoms at a particular time. One can be asymptomatic in the incubation period, and/or, in the period following the infection as shown by positive rtPCR which shows that an infection is present. It doesn't mean that they'll remain asymptomatic forever.

Presymptomatic means during the incubation period for the virus and you have no symptoms.

The antibody serosurveys getting underway in different parts of the country add further evidence that a good number – possibly anywhere from around 10 percent to 40 percent – of those infected might not experience symptoms.

And in this context, it meant the person remained asymptomatic throughout the whole infection.


  • I think I understood. However does that mean someone can remain asymptomatic for a longer period of time than the one that takes for someone who shows symptoms to get fully healed? Commented May 4, 2020 at 16:31
  • @Smart_Delay Calling someone "asymptomatic" says nothing about durations - you seem to be asking a question in a comment which is unrelated to this question about the meaning of asymptomatic.
    – Bryan Krause
    Commented May 4, 2020 at 18:49

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