Professor Hugh Pennington said that while we may be past the peak of the coronavirus pandemic, the number of cases is going down very slowly.
He said we are "in the hands of the virus" over when life could return to any kind of normality.
Latest figures on Thursday showed that 1,762 patients in Scotland have died after testing positive for Covid-19, up by 59 from 1,703 on Wednesday, while 12,924 people have tested positive for the virus, up by 215 from 12,709 the day before.
In an interview on BBC Good Morning Scotland, the University of Aberdeen emeritus professor was asked when life might be able to return to some kind of normality, with there having been some suggestions that nothing this year will be normal.
He replied: "We're in the hands of the virus. It entirely depends how the number of cases moves and of course the number of cases is moving down, but it's moving down rather slowly.
"We may be past the peak in the sense that the number of cases are not going up, but it's only going down very slowly.
"When I say we're in the hands of the virus, what I mean is the number of cases really determines what sort of actions or relief from lockdown we can have.
"We have to wait until the number of cases starts to come down substantially, and starts to come down on a regular basis, so basically we know we're controlling the transmission of the virus, preventing the transmission of the virus."
Former chief medical officer Professor Sir Harry Burns has suggested that everyone in Scotland should be tested for the virus.
Asked whether he thinks that is the right thing to do, Professor Pennington said: "If we did that we'd know a lot more about what the problem is, where the virus is, and we would be able to track it and control it by basically putting anybody who has it into isolation, and that would solve the problem."
Professor Pennington also said he hopes the UK-wide approach to tackling the virus continues and said it would be a "great pity" if there was any divergence.