Hot weather, Euro football: What is behind Britain's plummeting Covid cases?

A woman takes off her mask as she walks in Covent Garden, in London, Monday, July 19, 2021.
A woman takes off her mask as she walks in Covent Garden, in London, Monday, July 19, 2021. © Alberto Pezzali, AP

The number of confirmed new Covid-19 cases has fallen drastically in the UK over the past two weeks – a shocking piece of good news, defying expectations that the end of social distancing measures and the prevalence of the contagious Delta variant would see cases surging.


Recorded cases halved over the past two weeks, dropping from 54,674 on July 17 to 22,287 on August 2. Neither experts nor the British government expected this – with some forecasts projecting up to 100,000 new cases per day by the end of the summer and Health Secretary Sajid Javid urging people to remain careful after the vaunted “Freedom Day” ended social distancing measures on July 19.

“We were surprised” at the first signs that cases were in freefall in the week starting July 20, recalled Kevin McConway, former vice-president of the Royal Statistical Society and professor emeritus of applied statistics at the Open University.

Initially, many observers hypothesised that a drop in the number of PCR tests was responsible for this precipitous decline. But it soon became clear that this was too minor a factor to explain such an extensive phenomenon.

“Indicators show that hospital admissions of Covid-19 patients stagnated and then started to fall, which is encouraging and seems to confirm the hypothesis that there indeed is a significant decline in new cases,” explained Thomas Wingfield, a specialist in infectious diseases at the Liverpool School of Tropical Medicine.

So it is a “longer-term downward trend we’re seeing here”, McConway confirmed. “We knew there would be a slowdown in new cases after the big increase in early July – but not as quickly or as strongly,” he continued.

Surprising Euro effect

A constellation of different factors seems to have come good for Britain.

“The hot summer weather pushed people outside and to open doors and windows and thereby ventilate confined spaces,” Wingfield noted – bearing in mind that the coronavirus spreads less outdoors.

A more counter-intuitive reason for the decline in cases is the effect of the Euro 2021 football tournament – “which predictive models hadn’t taken into account at all,” McConway pointed out.

There was a surge in cases amongst young men during the Euros from June 11 to July 11, as this group flocked to pubs and stadiums in the largest numbers amid a surge of national exuberance as England reached the final with a series of barnstorming performances.

Consequently, many under-35s – who are least at risk of serious or even symptomatic infections – were protected against Covid-19 after the tournament because they had just acquired immunity. With the overwhelming majority of over-40s fully vaccinated thanks to the UK’s famously rapid jab rollout and an unusually large number of young people now resistant to the disease, it seems the virus had far fewer ways to spread than before.

The comparison between England and Scotland illustrates the Euro effect: “The decline in the number of new cases started earlier in Scotland after the Scottish football team was eliminated from the tournament earlier,” McConway observed.

Finally, it appears Brits have been much more cautious than experts predicted. “One of the main question marks hanging over the epidemiological models was on how people would behave after social distancing was lifted,” McConway said. The most pessimistic projections envisaged British subjects abandoning all cautions after July 19. But “I think the fact that people often continue to wear masks when shopping and keep their distance in confined spaces makes a big difference,” McConway continued.

So was Boris Johnson right to end restrictions on July 19, contrary to many scientists’ advice? It is “still too early” to say if the prime minister’s decision was apt, McConway said. Tellingly, the government has not yet trumpeted the fall in new cases. “There’s a danger of people lowering their guards if we rejoice too much – and that would likely cause new infections to increase,” he continued.

The decline in Covid cases could simply move the problem to the autumn, McConway warned. If the epidemic starts with a vengeance at the start of the school year in September, “nothing will have been gained, because hospitals tend to be busier from the autumn onwards due to an influx of patients with seasonal illnesses”, he warned.

Hence the absolute need for vaccine handouts to get jabbed, McConway concluded: “The data show that vaccines protect even against the Delta variant.”

This article was translated and adapted from the original in French.

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