Sir, – The ethical difficulty of reconciling a libertarian right to refuse Covid vaccination with the community-wide impact of such a viewpoint is interesting, and credit is due to Cormac O'Raiftearaigh for raising it ("Ethical and moral dilemmas in the time of Covid", Opinion, Science, December 30th). His conclusion that first-world politicians should pursue a global vaccination policy because "no one is safe until everyone is safe" is probably not sustainable, however.
Covid by now has become a zoonosis, with spread into numerous animal populations. These include deer, mink and cats, all of which move between wild and domestic or agricultural settings.
Thus the disease will in practical terms remain in circulation in animal hosts.
So even if we vaccinated everyone in the world right now it would recur, as new mutations will evolve in animal hosts. The 140 million people born next year would be completely vulnerable to it, for instance. The only significant human infection ever eradicated by vaccination, smallpox, was, crucially, not transmitted across species.
It is surely correct to say that universal vaccination should be offered as it is simply the right thing to do.
But eradicating Covid, or ending the emergence of new variants, is an unrealistic basis for that argument. – Yours, etc,
BRIAN O’BRIEN,
Kinsale,
Co Cork.