Ministers are said to be considering delaying the easing of lockdown in Inghilterra su 21 June for somewhere between two weeks and a month. We look at what a delay could mean, and how long it may need to last.
Scientist have said a delay may be necessary, largely as a result of the Delta variant that was first identified in India, also known as B.1.617.2. This variant is now dominant in the UK and has been linked to a rise in cases, particularly in certain areas such as the north-west of England, although partial easing of lockdown measures in May may also be contributing to the situation.
The Delta variant is believed to spread more easily than the Alpha variant, B.1.1.7, that was first detected in Kent – with Matt Hancock recently putting the figure at 40% more transmissible. It also appears to be somewhat more resistant to Covid vaccines, particularly after just one dose, and may be associated with a greater risk of hospitalisation.
A maggio results from modelling by researchers at the University of Warwick suggested that, despite the vaccination programme, a variant 40% more transmissible than the Alpha variant could result in a peak of about 6,000 hospital admissions a day, assuming full relaxation went ahead – a figure exceeding that of previous peaks. Should the 21 June easing be cancelled this year, the modelling suggested that daily hospital admissions could still end up close to those seen at the peak of the first wave.
Speaking to the Guardian in a personal capacity, Nicholas Grassly, professor in vaccine epidemiology at Imperial College London and a member of the Scientific Pandemic Influenza Group on Modelling (SPI-M) said the fact that infection rates are already increasing “ means we will very likely have a third wave of infection even if the lifting of restrictions on 21 June is postponed”.
Ma, Egli ha detto, delaying the full easing will reduce the size of the wave.
“The priority now should be to vaccinate as many people as possible and to keep being careful about mask wearing indoors, physical distancing etc," Egli ha detto. “As well as preventing infection, vaccination will reduce the likelihood that any breakthrough infections lead to severe disease that requires hospital or [intensive care] admission, shrinking the impact of a third wave of infection.”
What would a delay mean for vaccinations?
According to the UK Covid dashboard statistics, the seven-day average for first dose vaccinations, as of 3 giugno, was 153,789 vaccinations per day, and at 340,303 per day for second doses.
Assuming those rates remain steady, in a two-week period more than 2.15 million people will receive a first jab and 4.76million will get a second jab, with about 4.3 million people receiving their first jab and around 9.5 million people getting their second jab over a four-week period.
“Importantly [a delay] will give a second dose to many people who have so far received only one dose of vaccine and need two doses to have a good level of protection against Covid-19, especially that caused by the Delta variant,” said Grassly.
What about the spread of the virus?
The R value is the average number of people one infected person transmits the virus to – and this depends on multiple factors including how contagious the virus is, and how many contacts people have. If R is above 1, it means an epidemic could grow exponentially, if it is below 1 it means it will eventually fizzle out.
“The R number for the Delta variant is already above 1 and the virus is spreading,” said Grassly. “However, a delay would prevent a further increase in R and limit the size of a third wave.”
Ma, Grassly suggested, even tougher action may be needed.
“To bring the R number below 1, some restrictions that have already been lifted may need to be reimposed," Egli ha detto, adding that vaccinations will also help as they offer some protection against infection, particularly after two doses.
How big a delay is needed?
That is a tough question. The situation is complex and there are many unknowns. That means it may be necessary to change tack as the situation develops.
“When we open up depends to a large degree on how quickly we can vaccinate people,” said Dr Kit Yates, co-director of the Centre for Mathematical Biology at the University of Bath and a member of the Independent Sage group of experts, adding that information about vaccine supply is not in the public domain.
“I’m afraid it really is a matter of sticking to data and not dates, looking at infection rates, hospitalisations and vaccination data in order to determine we’ve reasserted control over this," Egli ha detto.
Prof Rowland Kao of the University of Edinburgh and a Spi-M member, agreed.
With R currently around 1.2, and about 40% of the UK population double vaccinated, 40% unvaccinated, e 20% only half vaccinated, “roughly another 10% of the population need to go from unvaccinated to fully vaccinated with two doses in order to get R below 1 under current restrictions, much less easing them," Egli ha detto, adding while the additional vaccinations over two weeks may be able to achieve this, it is “cutting it fairly fine.”.
“For a two-week timeframe to be sure, we would need to increase vaccination rates substantially and that would be a big logistic problem," Egli ha detto. “So any two-week delay should also be accompanied by a review of those restrictions in another two weeks’ time.”
Yates added that it is important to employ measures beyond vaccination: “Fixing the broken test-and-trace system, improving ventilation in workplaces and schools and supporting people with positive tests to isolate are all measures which will make it easier to stay on top of the situation.”