The Scottish Government adviser urged young people to come forward for the injections, saying “to get out the end of the pandemic, globally and in Scotland, we need big population immunity numbers”.
The number of vaccinations reached a three-month low earlier this week, with 17,749 injections – including 7,163 first doses – administered on Monday, and Prof Leitch appealed to those who have not yet come forward.
He said changes to travel regulations, which mean those who have been fully vaccinated no longer need to isolate after returning home from amber-list countries, could encourage more people to be inoculated.
Speaking on BBC Radio Scotland’s Good Morning Scotland programme, he said: “If travel is an incentive for you, here’s another reason, if you needed another reason other than the illness, to get yourself vaccinated.”
He urged people to “please, please, please get yourself vaccinated”.
The latest figures from Public Health Scotland show that in the four weeks between June 12 and July 9, almost two-thirds (64.7%) of confirmed coronavirus cases were among the unvaccinated.
Just over half (51.6%) of Covid-19 hospital admissions for the same four-week period involved unvaccinated individuals, with 70.6% of this group aged under 40.
Asked about the rate at which people are being vaccinated, Prof Leith said he would “agree things have slowed down a little bit”.
He said there are two reasons for that, with the first being “unavoidable” because “you can only do second doses if you have done first doses”.
Prof Leitch continued: “If you did 10,000 first doses eight weeks ago you can do 10,000 second doses today, give or take a few. So that’s fixed, and that is going well, people are coming for their second doses. There’s no suggestion people are fed up and disappearing.”
But he said the “tricky one, that’s harder for us to control” is getting 18 to 29-year-olds to come forward for their first vaccination.
He added: “That number, that first dose number, is slowing a little bit. We expected it to at this age, and we’ve done actually quite a lot of them. The more stubborn ones, maybe a little bit hesitant, maybe busy in jobs in whatever else they’re doing, we really, really need them to come.”
To try to encourage more younger people to come forward, drop-in clinics have been set up across the country in each health board area, with Prof Leitch explaining that “we’re trying to get the vaccine as close to them as we possibly can”.