However some expressed concerns around complicating factors affecting uptake and its impact, such as parental choice, cultural differences, and herd immunity.
Fodd bynnag, gwnaeth rhai fynegi pryderon ynglŷn â ffactorau sy’n cymhlethu penderfyniadau ynglŷn â brechu ac effaith hynny, megis dewis rhieni, gwahaniaethau diwylliannol, ac imiwnedd torfol.