There could have been as many as 700,000 people in September with a higher chance of contracting Covid as they had not yet been exposed to the virus. By the end of October, there might still be about 500,000 such people.
These are the rough estimates of Richard Kollár, a mathematician and member of the Science Helps initiative.
It is hard to say how protected against the virus people in Slovakia are. Scientists would have to know not only how many people have been vaccinated and how many tested positive for Covid, but also how many people encountered the virus and how many have antibodies but do not know about it.