There might be good reasons for some reluctance to have the jab but there may also be unacceptable ones.

But make no mistake: hesitancy is ultimately harmful.

Researchers at the Burnet Institute in Melbourne say Australia is unlikely to achieve herd immunity (in which the virus peters out because not enough people catch it and then re-transmit it) while the current levels of reluctance remain.

There might be some understandable reasons for reluctance.

This week health authorities have recommended that people under 60 should be offered an alternative to the AstraZeneca vaccine, an increase from under 50.

But many medicines have side effects.

Doctors learn about them and prescribe accordingly.

If every highly unlikely side-effect of every medicine was given big publicity, we might be hesitant about many other highly beneficial drugs.

On the latest figures, about one-in-five adult Australians have been vaccinated.

Another half of the population want to be vaccinated.

But that leaves around a quarter who don't want to be vaccinated or who don't know whether they do.

Some may wrongly imagine that they can keep themselves isolated from further outbreaks.

But, as Melbourne knows, the virus will keep coming back.

Some might also see it as a matter of personal freedom.

This, though, is an irresponsible and wrong-headed argument.

Our personal freedoms are often curtailed for the greater good of society.

The government needs to do all it can to remove the legitimate doubts.

It should also move more quickly on opening the border.

It might be politically convenient to delay the opening but the delay means people might imagine that they can postpone the jab.

On the current evidence, we are not heading to anywhere near that level and without it, the virus will recur in a never-ending cycle of infection and re-infection, all complicated by new variants.

A return to true normality demands more vaccination.

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