Photo: HUGO DELGADO/LUSA

Covid herd immunity “is probably impossible”: Portuguese experts confirm latest research

Forget the notion that with 70% of the population vaccinated countries will be at a point of reaching ‘herd immunity’ from Covid-19.

New data emerging suggests five principal reasons why herd immunity is “probably impossible” – and Portuguese experts absolutely agree.

Reacting to a recent article in British scientific journal Nature, Paulo Paixão, president of the Portuguese Society of Virology says “for me, the notion that the virus will not stop circulating even when we have 70% to 80% of the population immunised is not new. 

“We cannot totally block circulation of the virus. This is a concept that simply doesn’t apply to respiratory viruses – flu is the best example”, he said

The nirvana of herd immunity has been in question for months but now data modelling experts have proof of its elusiveness: Israel, for example, is almost at the point where 70% of its citizens have been vaccinated, but new cases continue to spiral “well above the current incidence in Portugal”.

So, the five principal stumbling blocks are:

  • Vaccines do not appear to stop transmission (this hasn’t been universally ‘agreed’ but it is a given among the scientific community, both here and elsewhere (click here)
  • Vaccine manufacturers cannot supply the whole world evenly
  • New variants ‘are appearing all the time’: some rendering the vaccines less effective
  • No-one knows how long immunity – either conferred by the vaccines or natural infection – will last
  • Some people will refuse to be vaccinated on the basis of all the above and ‘other unknowns’, particularly what long-term side effects the vaccines could have.

The ‘boon’ of the vaccination process seems to be that it has drastically reduced the severity of Covid-19 infections: less people are dying, less are ending up in hospital.

In other words, the virus is still circulating, but it is not as lethal.

Epidemiologist Elisavbete Ramos believes this is the best we can hope for: that less people susceptible to becoming ill end up in hospital putting pressure on public health services.

It’s not a traditional ‘herd immunity’ but it is an immunity that avoids the most serious effects of Covid-19 “which is unlikely to be eliminated completely”, she agrees.

And because countries do not live ‘closed off from each other’ – and some will control the virus better than others – there will always be “a very high probability that new variants will occur that overwhelm the immunity of those who have been vaccinated”, she said.

Slowly, the enormity of how much the world will have to change is seeping into the media narrative.

Herself president of the Portuguese Association of Epidemiology Elisabete Ramos said that she believes with 70% of Portuguese vaccinated “we will be able to go back in certain aspects to our normal life, but not to the normal that we had before – particularly while there lacks a more global control of the illness”.

And then there’s the even bigger question which Paulo Paixão and Elisabete Ramos see coming: once everyone has been vaccinated, “will it be necessary to go back to the beginning and do it all again”?

natasha.donn@algarveresident.com