[mamon]

Maybe they mean "mRNA vaccines"? COVID vaccine is the first of this kind, so some side effects, especially long term ones, are still unknown. It's still unlikely that they would be very serious but we won't know for sure until 10 years from now.

[andruby]

In case people really have concerns about the newer mRNA vaccines, perhaps they can choose the AstraZeneca vaccine, which is a more traditional one.

[hda111]

Both are more or less new. The AZ method is only known from Ebola vaccines but they were not not used globally.