[katieHaylor (OP)]

Bill asks:

If someone contracts Covid-19 but has no symptoms does this mean their body is not fighting it? And will they just be walking around producing the virus and spreading it until they are vaccinated or die?

[set fair]

Many asymtomatic people are tested eg through contact tracing, some test positive and remain asymptomatic but later test negative. So what Bill asks about isn't the norm but that doesn't mean it never happens - a second positive a month later and asymptomatic throughout could be chalked up as a false positive. Would it be noticed if an asymptomatic  individual went on spreading the virus for more than a month, more than 3 months? Perhaps not if nobody is specifically looking for it.

[evan_au]

If someone contracts Covid-19 but has no symptoms does this mean their body is not fighting it?

Most of the "common cold symptoms" are caused by interferon, one of your body's first reactions to viral infection.
- But SARS-COV2 has a gene which suppresses interferon, increasing the chance of asymptomatic infection and spread
- If you have a normal immune system, your body will eventually start fighting the virus, but without the interferon alarm, it might take longer to get started. Until your body eliminates the virus and the infected cells, you will still be shedding virus. Many of the fatal cases seem to be an immune over-reaction, once it finally gets the message...
- If your immune system is compromised, the immune response will be less effective. That means:
    a) the virus could spread through your body and kill you, or
    b) you could have a chronic infection, where you keep shedding virus, but it doesn't cause fatal damage.

Vaccines don't suppress interferon, so they will produce a faster immune response than the virus itself.