Vaccinations alone are unlikely to contain coronavirus infections in the UK, a new study suggests.
However, the research concluded that gradually easing lockdown restrictions and achieving high uptake of COVID-19 jabs can minimise future waves.
The University of Warwick’s modelling was performed before early real-world data emerged from studies examining the impact of the vaccine rollout.
Professor Matt Keeling said: “Our modelling suggests that vaccination rollout in adults alone is unlikely to completely stop COVID-19 cases spreading in the UK.
“We also found that early sudden release of restrictions is likely to lead to a large wave of infection, whereas gradually easing measures over a period of many months could reduce the peak of future waves.”
He added that the huge success of the UK’s vaccine rollout so far – coupled with the government’s gradual roadmap for easing restrictions – are cause for optimism.
“However, some measures, such as test, trace, and isolate, good hand hygiene, mask-wearing in high-risk settings, and tracing from super-spreader events, may also be necessary for some time,” Prof Keeling explained.
The study was published in Lancet Infectious Diseases and modelled the combined vaccine rollout in the UK with different scenarios of relaxing lockdown measures. The goal was to predict the R number, as well as COVID-related deaths and hospital admissions, between January 2021 and January 2024.
In the model, it was assumed vaccine uptake would be 95% in those aged 80 years and older, 85% in those aged 50 to 79 years, and 75% in those aged 18 to 49.
Vaccine protection against symptomatic disease was assumed to be 88% based on phase three trial data from the Pfizer/BioNTech and Oxford/AstraZeneca vaccines being administered in the UK.
The findings suggest that, although vaccination can substantially reduce the R rate, it may not be enough to drive R below one without other control measures.
According to researchers, the scale of future waves – and the number of deaths they cause – will be influenced by how early measures are relaxed, the timescale with which they are eased, the vaccine’s level of protection against infection, and uptake of the jabs.
The model estimated that partially easing lockdown restrictions in February 2021 would lead to 131,100 coronavirus deaths in the UK by January 2024.
It was also predicted that partially easing measures in April 2021 would lead to 61,400 deaths by 2024, while starting to remove restrictions in June 2021 would result in 53,900 deaths.
If all lockdown measures are removed in January 2022 – after the rollout of the vaccine has been completed – estimates suggest there will be 21,400 COVID-19 deaths over the two years that follow.
Dr Sam Moore, also from the University of Warwick, added: “Since we conducted this study, new evidence suggests there may be a higher level of protection against severe disease offered by both the Pfizer/BioNTech and Oxford/AstraZeneca vaccines than the level we assumed.
“This may reduce the size of future hospital admissions and deaths we estimated, making future waves more manageable for the health service.”
The model did not account for the emergence of new variants that may cause jabs to offer less protection, nor the effects of waning immunity, which may mean that additional vaccinations are necessary.
Researchers were also unable to ascertain the impact that relaxing specific lockdown measures would have on future cases and deaths.