If that means what I think, then the advice should be : "don't go to 2019 or later". Shouldn't it?
The COVID19 is called COVID19 because it spread since 2019. In China at first, apparently (although there are earlier remnants in sewage in other places IIRC).
And if I've understood it, there's plenty of coronaviruses around still today, it's just that most people got relatively immune and their effects aren't so grave.
But if someone from before 2019 travelled in time to any year after 2019 (or 2019 depending on their luck and the place they land on) and got back to a year
prior to 2019 they could start a pandemic likely to change history in lots of ways. This would be even more likely if they traveled to 2022 or later, since in
2020, at least the second half, or the last 3 quarters, there were more preventive measures than today, and he might be less likely to catch and bring the virus back to the past
that nowadays when people don't wear masks, distance, confine, etc... In 2020 he could catch a variant of the virus more deadly but less contagious, and now a variant more contagious and less deadly, but it would be more likely to catch it.