Boris Johnson, the British Prime Minister, postponed by a month his intention to eliminate the last COVID-19 restrictions in England after modeling revealed that thousands more people could die if the reopening was not postponed.

The decision was made in response to the rapid spread of the Delta coronavirus strain, which is more transmissible, has been linked to decreased vaccination effectiveness against mild sickness, and could result in more hospitalizations among those who have not been vaccinated.

He said the extra time would be used to accelerate Britain’s vaccination program, which is already one of the most advanced in the world, with two-thirds of the population scheduled to have received two injections by July 19.

The following are the specifics of the decision:

WHAT ARE MODELS AND MODELLERS, AND WHO ARE THEY?

According to models commissioned by the government in circumstances where ministers felt the health system would be overburdened, hospitalizations might reach previous highs without delaying the planned June 21 reopening.

The government’s pandemic modelling subgroup SPI-M-O used three models developed by the London School of Hygiene and Tropical Medicine, Imperial College London, and the University of Warwick.

A delay, according to all three, reduced the peak of a fresh wave fueled by the Delta variation. According to SPI-M-O, a two-week extension would have a substantial impact, but four weeks would cut the peak in hospital admissions by a third to half.

SPI-M-O will make fresh projections before July 19 when the full reopening is now expected to take place, with Johnson saying that he does not want to delay reopening again.

WHAT ABOUT THE VACCINES?

Britain has one of the fastest vaccine rollouts in the world, with over half of adults receiving both doses and more than three quarters receiving at least one, which has led some to question why restrictions need to be extended.

The modelers warned that while protection from vaccines was not perfect, without them, England would be heading back into lockdown.

Imperial epidemiologist Anne Cori told reporters that differences in who was eligible, in rates of uptake, and the fact that vaccine effectiveness was not 100%, all combined to create the possibility of a large wave of hospitalizations.

VACCINE AND DELTA

Evidence suggests that the Delta variation diminishes vaccination protection against symptomatic illness, yet experts anticipated it would still work against severe disease.

As Johnson announced the deferral, Public Health England released data demonstrating that Pfizer and AstraZeneca’s vaccines give 96 percent and 92 percent protection against hospitalization from the variation found in India, respectively, after two doses.

When asked if the data, which was provided after the models were created, would have an impact on the estimates, Cori explained that they had employed different efficacy assumptions in their models and that the PHE figures would help to narrow down the range of possible possibilities.

“The optimistic vaccine efficacy or perhaps the central (scenarios) are definitely more likely than the most pessimistic set of vaccine efficacies we had looked at,” she said.

WHAT ARE THE SOCIAL-ECONOMIC COSTS?

Many lawmakers in Johnson’s own party expressed dismay at the delay, with Steve Baker saying some people “increasingly believe they are never going to see true freedom again”.

The delay, according to Kevin McConway, emeritus professor of applied statistics at The Open University, will give researchers more time to learn about the Delta variation and receive more bullets in arms.

However, he stated that the heightened hazards of opening on June 21 were difficult to calculate.

“I do wonder how the government can make good decisions on the balance between restrictions on what we can do,” he said, “when they have detailed modeling of infections, vaccines, hospitalizations, and deaths (including information on the likely uncertainties), but no detailed modeling (that I’ve seen) on the economic and social costs of the restrictions.”