Herd immunity is “not a possibility” with the dominant Delta variant of coronavirus, an expert has said.
Professor Sir Andrew Pollard, director of the Oxford Vaccine Group, referred to the idea as “mythical” and warned that a vaccine programme should not be built around the idea of achieving it.
Herd immunity is when enough people become resistant to a disease – through vaccination or previous exposure – that it can no longer significantly spread among the rest of the population.
While the statement is concerning, Professor Paul Hunter, an expert in infectious diseases at the University of East Anglia, said we should avoid “frightening ourselves,” as high case numbers do not necessarily mean high hospitalisation.
Many people will now experience the virus without symptoms, he added, so we should move towards language that reflects the “endemic” nature of the virus.
Professor Pollard told a session of the All-Party Parliamentary Group on Coronavirus (APPG): “We know very clearly with coronavirus that this current variant, the Delta variant, will still infect people who have been vaccinated and that does mean that anyone who’s still unvaccinated, at some point, will meet the virus.”
He said while vaccines might “slow the process” of transmission down, they currently cannot stop the spread completely.
“I think we are in a situation here with this current variant where herd immunity is not a possibility because it still infects vaccinated individuals,” he added.
He predicted that the next thing may be “a variant which is perhaps even better at transmitting in vaccinated populations”.
He added: “So, that’s even more of a reason not to be making a vaccine programme around herd immunity.”
Reducing the risk
The parliamentary group’s chairwoman, Liberal Democrat MP Layla Moran, called on the government to “re-evaluate their approach” and put together a “new and comprehensive” plan to mitigate the risks from new variants.
She said: “The worrying evidence we heard today suggests that given the emergence of new variants, including vaccine-resistant ones, achieving herd immunity is just a pipe dream.
“The government’s plan to learn to live with Covid cannot become a byword for abdicating responsibility to the most vulnerable. Ministers must re-evaluate their approach and come up with a new and comprehensive, long-term plan to mitigate the risks posed by Covid and new variants.
“That must include showing moral leadership and stepping up efforts to vaccinate the world.”
Professor Pollard said while there might be “bumpiness” in the next six months, there is also likely to be “increasing confidence” with the UK’s virus situation.
He told the APPG: “I think this next six months is a really important consolidation phase and in that shift from the epidemic to the endemic, which is the ‘living with Covid’. That doesn’t mean that we live with it and put up with it – we still have to manage those cases of patients who become unwell with it.”
‘With Covid’ or ‘because of Covid’?
Professor Paul Hunter said the way infections are reported might need to change as Covid-19 becomes endemic so that people are not “frightening ourselves” with high numbers “that actually don’t translate into disease burden”.
He told the the session: “I think we need to start moving away from just reporting infections, just reporting positive cases admitted to hospital, to actually start reporting the number of people who are ill because of Covid, those positives that are symptomatic.
“We need to be moving towards reporting hospital admissions that are admitted because of Covid, not because they just happen to be positive and they’re being admitted for something else.”
He said the distinction in someone being ill with Covid or because of Covid is not always an easy one to make for clinicians, but added: “I think we’ve got to start moving to that, otherwise as infection becomes endemic we are going to be frightening ourselves with very high numbers that actually don’t translate into disease burden.”