As others have tried to point out, the numbers infected are meaningless really if you haven't tested everyone.
Let's take a hypothetical situation-
2 countries of 10 million each with an open border, now, country A tests all 10 million and says 6 million carry the virus-
country B tests no one and says they have no cases of infection.
Now, does anyone actually believe that country B would be virus free? Of course not, yet we have e.g. Thailand with infection cases, yet Myanmar and Laos have none? Would anyone in their right mind think that to be the actual case?
The countries i mentioned are just as an example, used to emphasise the point that some are testing more than others, so the figures are skewed and somewhat meaningless at this stage.
The best advice i have seen since this all started is to act as if you do have it and behave accordingly, i.e. keep as much distance from others as possible and wash your hands frequently.