UK May Not Reach Herd Immunity Even With Vaccines, Sage Warns
The UK may not be able to reach herd immunity against coronavirus even if 75% of the population is vaccinated, scientists advising the government have warned.
In a paper modelling the impact of lifting lockdown, the Scientific Advisory Groups for Emergencies (Sage) outlined scenarios showing there could still be tens of thousands of deaths even after tens of millions of people are vaccinated.
The report, published on Friday but written in early December, states the number of deaths is also “critically” dependent on how much vaccines reduce transmission – that is, people passing on the virus to another person even if they are protected from serious illness themselves.
To reach herd immunity, there needs to be “very high” vaccine coverage of the adult population and vaccines would need to be highly effective against transmission.
Even in this scenario, there is a risk that there could be a resurgence of Covid, if we return to pre-pandemic life, which has the potential to force the reimposition of restrictions “to prevent the NHS from being overwhelmed”.
There is consensus that unless vaccines are highly effective against transmission, even coverage of 75% would not be sufficient to avoid further epidemic waves
Sage outlined a scenario in which 75% of the adult population was vaccinated, and the virus was 75% effective at reducing transmission, causing a total reduction in the amount of people passing on the virus of 44%.
“Whilst undoubtedly highly beneficial, whether this could prevent further epidemic waves is unclear,” Sage’s Scientific Pandemic Influenza Group on Modelling, Operational sub-group (SPI-M-O) said.
“There is consensus that unless vaccines are highly effective against transmission, even coverage of 75% would not be sufficient to avoid further epidemic waves following a post-vaccination return to pre-Covid life.
“Such a resurgence has the potential to require re-imposed restrictions to prevent the NHS from being overwhelmed.”
But...
