Vaccines have had an enormous impact on the course of the pandemic and have helped to weaken the link between the virus, serious illness, hospitalisations and death.
Mae brechu wedi cael effaith enfawr ar hynt y pandemig ac wedi helpu i wanhau'r cysylltiad rhwng y feirws, salwch difrifol, derbyniadau i ysbytai a marwolaeth.