Covid-19 vaccination is having an effect on cutting cases and death rates, with things looking optimistic for the summer months, an expert has said.
Modelling by University College London (UCL) researchers suggests the reproduction number (the R) for coronavirus was 0.75 on February 2, which means the epidemic is shrinking.
Professor Karl Friston said the team had produced a “most likely” scenario going forward, with a “progressive and gradual unlocking” of society as restrictions are lifted.
He said that by July the UK could have reached a place where some people will still have ongoing infections but a form of “herd immunity” is reached via vaccination, natural immunity and social distancing.
“Technically, all herd immunity means is you’ve stopped exponential growth,” he said, with the R number under one and no more need for lockdowns.
Prof Friston, who is the scientific director at the Wellcome Centre for Human Neuroimaging, added: “The bottom line is that vaccination appears to be having a tangible effect on confirmed new cases and daily death rates recorded over the past few weeks.
“If the vaccination programme continues to unfold at its current pace – and lockdown is eased gradually as a function of declining prevalence – we might attain herd immunity by as early as July.
“This encouraging (perhaps optimistic) forecast accommodates fluctuations in viral transmissibility.
“However, there is a lot of uncertainty about transmission risk that should nuance any interpretation of these predictions.
“These long-term predictions reflect a material response to the third lockdown that is clearly evident in declining incidence, hospital admissions and daily death rates.
“At present, the reproduction ratio is estimated to be the lowest it has been since late April but is likely to rise gently again as restrictions are eased over the forthcoming months.”
Some scientists urged caution over the modelling, with Mark Woolhouse, professor of infectious disease epidemiology, University of Edinburgh, saying: “At the present time it is very difficult to estimate when or even if the UK’s Covid-19 vaccination programme will bring us to the herd immunity threshold.
“The UCL study estimates the extent to which vaccination interrupts transmission which is one, but only one, of several unknowns about the long term impact of the vaccination programme.”
Last month, Professor Paul Hunter, from the University of East Anglia, warned that herd immunity, where the unvaccinated are protected by others having the vaccine, cannot be achieved either through natural infection or the programme using the Pfizer/BioNTech and Astra Zeneca jabs.
He told Radio 4’s Today programme that vaccines would allow a return to near-normal life for large parts of society but those who refuse a jab will not be protected in the traditional sense by herd immunity.
He said: “The rolling out the vaccine is going to make a huge difference and going to enable us to relax many of the restrictions that we’re under at the moment and, certainly as we’re moving into spring when the better weather comes along, that’ll considerably help.”
Prof Hunter said it was going to be “pretty much impossible” to reach herd immunity with the vaccines or through naturally-acquired infection.
While vaccines were “very good at stopping people getting severe illness and dying” and will suppress spread of infection to other people, they will not completely stop it.
“There will continue to be a risk to those people who are not vaccinated,” he said.
The UEA study suggests that everyone, including children, would need to be inoculated with the Pfizer jab, which it said was “more effective” than the Oxford/AstraZeneca one, in order for the UK to achieve herd immunity.