Chief Clinical Officer Dr Colm Henry has suggested the rapidly changing picture of the virus may mean herd immunity can't be achieved.
He says the best way to approach it is to make sure as many people as possible are vaccinated:
"We now know we've dealt with two successively more transmissible types of the variant. And I think our aim now is not to reach, some maybe elusive goal of 90/95% or whatever it is of the population, but to vaccinate as many people as possible. The virus being what it is, where mutates and new versions come along, it may well be that this concept of herd immunity doesn't really apply to something like the virus."