A sharp fall in the number of people in the United Kingdom testing positive for Covid-19 over the past six days has surprised and delighted scientists who feared cases would rise towards 100,000 a day, as health secretary Sajid Javid had warned in early July.
The latest daily count of 24,950 new cases, released on Monday afternoon, was the sixth successive decline – less than half the peak of 54,674 reached on July 17th and the lowest for three weeks.
"The recent fall in cases in England is great news, but also puzzling given that progressive relaxation of restrictions has occurred," said Stephen Griffin, a virologist at the University of Leeds.
“We need to be pleased about the recent fall in daily numbers of positive tests,” said Adam Finn, professor of paediatrics at Bristol university. “That means less viral transmission and eventually fewer hospitalisations and deaths than we feared and expected a week ago.”
But other experts said they had already dismissed scenarios in some epidemiological models that showed positive tests increasing beyond 100,000 a day later in the summer as a consequence of the government removing almost all legal curbs on social interactions from July 19.
“When I heard about a surge of that size I didn’t believe it,” said Paul Hunter, professor of medicine at the University of East Anglia. “It was way over the top because we were already seeing the Delta [variant] epidemic beginning to plateau.”
Why are cases falling?
The reasons why cases are dropping so fast now – and the prospects for the next few weeks and months – are far from clear, so Downing Street struck a cautious tone on Monday.
‘Not out of the woods yet’
British prime minister Boris Johnson’s spokesman noted that the impact of step-four easing – dubbed “freedom day” – had not yet been reflected in the figures. “The prime minister thinks we’re not out of the woods yet”, he said. “Obviously any reduction in cases is encouraging, but the PM has stressed many times that the pandemic is not over.”
"The daily test numbers will only begin to see the effect of the end of lockdown towards the end of this week," said Prof James Naismith of Oxford university, director of the Rosalind Franklin Institute. "Many scientists, myself included, expect the end of lockdown to see a rise in cases. However . . . this is a new disease and we are learning more every day."
Finn listed some of the factors at play, including infection-induced immunity, vaccine-induced immunity, and behaviour.
“We still have enough non-immune people around to reverse this trend if we completely stop trying to avoid spreading the infection,” he said. “But with every passing day another cohort of people, recently immunised, is added to our protection alongside those who have recently had the infection, survived and recovered.”
According to the latest estimate by the Office for National Statistics, 92 per cent of adults in England and Wales have antibodies to Sars-Cov-2 in their blood, through vaccination or previous infection. Although most scientists now shy away from the term “herd immunity”, because of its past connotation of letting the virus rip through the population with little control, a growing majority of people now have some immune protection against Covid-19.
Some of the past week’s fall in cases may be due to a decline in the number of people taking tests, perhaps because they want to avoid self-isolation, but experts say the drop is too steep for that to be the main reason.
The end of the school year is likely to be one factor. So is the end of the Euro 2020 football tournament. There is good evidence in the data that each England game in the Euros was followed by a spike in cases – not only from people going to matches but mainly from gatherings in homes and pubs to watch on television.
“It never occurred to me that the Euros would have as big an impact as they seem to have had,” said Hunter. “Ironically, that may make the next six months a little easier,” he added, referring to the increased amount of immunity the competition may have generated.
Has the wave peaked?
But hospitalisations rather than positive tests remain the key metric. So far, these have tracked cases with a seven-day lag so they, too, are likely to start declining this week.
Economists said confirmation in the next few days that the latest UK coronavirus wave had peaked would raise economic prospects again just as fears were mounting that the Delta variant would undermine the outlook for recovery this autumn.
Gertjan Vlieghe, outgoing member of the Bank of England’s Monetary Policy Committee, warned on Monday that Delta was “still causing health and economic damage, both in the UK and in the rest of the world, in a way that risks feeding back to the UK, economically”.
With Capital Economics estimating that the high numbers of people self-isolating in July could cut the level of activity in the economy by 0.5 per cent to 1 per cent, an easing of the pressure would put the recovery back on track to be as rapid as expected earlier in the summer.
Holger Schmieding, chief economist of Berenberg Bank, said on Monday that caution was still needed but the more positive signs from the Delta wave in the UK, Belgium, Portugal and the Netherlands suggested that “advanced economies can get through the current wave of infections without having to reimpose economically damaging restrictions”.
In the US and some other countries where Delta arrived later than in the UK, cases are still surging but governments are reluctant to impose stringent new restrictions. – Financial Times Service 2021