Being infected just means your cells have been infected and are starting to produce more viruses. That process is heavily dependent on viral load and the host's

Being infected just means your cells have been infected and are starting to produce more viruses. That process is heavily dependent on viral load and the host's immune system. You're only symptomatic when your body begins a whole scale fight against the virus, before that, your body is still producing the virus (and you can spread it), but the virus isn't impacting you enough to be symptomatic.