England’s national lockdown will need to be replaced with stricter measures than the previous three-tier structure, scientists advising the government on the spread of coronavirus have said.
“If England returns to the same application of the tiering system in place before November 5, then transmission will return to the same rate of increase as today,” ministers were told on November 4.
The warning was included in a paper produced by the Scientific Pandemic Influenza Group on Modelling (SPI-M-O), a subgroup of the Scientific Advisory Committee for Emergencies (Sage).
November 4 was the day before the four-week national lockdown came into force.
Boris Johnson had hoped his tiered system of local lockdowns would be enough to suppress the virus.
But in the end the prime minister decided to go further and impose nationwide restrictions closer to those introduced in March, due to the rate at which infections were rising.
He has all but promised the four-week national restrictions will end on December 2 and be replaced with a return to local interventions.
It has been reported a new tier 4 could be added to the current three levels, which would impose even stricter restrictions than tier 3.
In the paper, made public on Friday, SPI-M-O said: “The longer-term outlook depends on both the nature of non-pharmaceutical interventions that are implemented in England after 2 December and policies over the festive period.
“If England returns to the same application of the tiering system in place before 5 November, then transmission will return to the same rate of increase as today.”
The experts said its analysis had showed there had been a “clear effect” on the infection rate from tier 3 interventions, although “much less” from tiers 1 and 2.
But they warned: “It is not yet clear whether tier 3 measures alone are sufficient to reduce the reproduction number below 1.”
MPs will get to vote on what replaces the national lockdown, and the prime minister may have to rely on Keir Starmer and Labour votes following the formation of a 50-strong group of Tory MPs opposed to any new lockdown.
The analysis was released shortly after official estimates suggested the reproduction number, or R rate, of coronavirus transmission across the UK has dropped to between 1.0 and 1.2.
R measures the number of people, on average, that each sick person will infect. If R is greater than 1 the epidemic is generally seen to be growing; if R is less than 1 the epidemic is shrinking.
But there is a time lag on the data, and Sage cautioned it represents the situation over the “last few weeks” and does not reflect “any very recent changes” in transmission as a result of “recent policy changes” - such the national lockdown.