Scientists are urging people not to rely on those who have been vaccinated against Covid-19 to keep them safe, as it is “pretty much impossible” for the UK to reach herd immunity.
While vaccines will allow a return to normality for large parts of society, people who have not been immunised will be at ongoing risk from coronavirus.
Vaccines won’t completely stop infection
Professor Paul Hunter and colleague Alistair Grant, from the University of East Anglia, have warned that herd immunity cannot be achieved either through natural infection, or by the rollout of the Pfizer and Oxford vaccines.
Prof Hunter said that although vaccines will make a huge difference in stopping people from getting ill and suppressing the spread of infection, they will not completely stop it.
As such, people who refused to have the vaccine will continue to be at risk.
Speaking on Radio 4’s Today programme, Prof Hunter said: “I think there are two key issues.
“The first is that if you are uncertain about whether you want the vaccine or not - and especially if you’re a vulnerable person - you cannot rely on the fact that your neighbours have been vaccinated so please, please, please make sure you go and be vaccinated yourself.”
The second issue is that those who have not been vaccinated will be at ongoing risk from coronavirus, so appropriate tracking and tracing systems need to be in place to identify local outbreaks and stop them.
He added: “This is something that happens in measles…particular communities with low uptake of measles vaccines can have suddenly very nasty, very severe outbreaks of measles and what you have to do is make sure we’ve got systems in place to spot these early before they become real problems for the people concerned.”
Herd immunity ‘impossible’
Prof Hunter explained that it was going to be “pretty much impossible” to reach herd immunity with the vaccines or through naturally-acquired infection.
The vaccines will help to prevent people becoming severely ill and dying, and while the spread of infection will lower, the virus won’t be eradicated entirely.
“There will continue to be a risk to those people who are not vaccinated,” he said.
Meanwhile, Professor Sir Mark Walport, who is advising ministers as a member of the Scientific Advisory Group for Emergencies (Sage), said that “all the evidence says have a vaccine”.
The UEA study suggests that everyone, including children, would need to be inoculated with the “more effective” Pfizer jab in order for the UK to achieve herd immunity.
Oxford jab ‘less effective’ in controlling virus
The scientists recommend that all health and social care professionals should be vaccinated with either the Pfizer or Moderna jabs, both of which have reported around 95 per cent efficacy in clinical trials, in order to prevent patients and vulnerable people from becoming infected.
Researchers used mathematical modelling to assess how effective the Oxford and Pfizer vaccines would be in bringing the coronavirus reproduction number (R) down.
Initial findings showed that 69 per cent of the population would need to be given the Pfizer jab, or 93 per cent the Oxford vaccine, to bring the R number below 1.
However, when taking into account the highly transmissible UK variant, they found that vaccinating the entire UK population with the Oxford jab would only reduce the R value to 1.3.
Prof Grant said the combination of “relatively low headline efficacy and limited effect on asymptomatic infections” means the Oxford vaccine “cannot take us to herd immunity, even if the whole population is immunised”.
He said: “For this reason, we recommend that health and social care workers, and others who have lots of contacts with those vulnerable to infection, should receive one of the mRNA vaccines in preference.
“The Oxford vaccine will no doubt be an important control intervention, but unless changes to the dose regime can increase its efficacy, it is unlikely to fully control the virus or take the UK population to herd immunity.”