As the first data on the new Delta variant of Sars-CoV-2 began to trickle through in April and early May, Martin McKee was immediately convinced that a third wave of Covid-19 was imminent.
McKee, a professor of European public health at the London School of Hygiene and Tropical Medicine, was particularly shocked when he saw estimates of Delta’s R number, the average number of people that one infected person will go on to infect with the virus. “You could see this was a much more transmissible variant,” says McKee. On June 16, Public Health England’s strategic Covid-19 response director told MPs that if the new variant was left to spread uninhibited, its R number could be between five and seven.
For McKee, it seemed inevitable that new cases of Covid-19 – which had been steadily declining since early January – would begin to rise again. On June 24, the number of daily infections in the UK crossed 16,000, levels not seen since early February when the UK was still in full lockdown.
But the third wave will look very different to the last two. While the Delta variant is considered to be more virulent than any that have previously followed, the UK’s successful vaccination campaign appears to have broken the seemingly inevitable link between cases, hospitalisations, and fatalities. The current hospitalisation rate remains low. There were 182 new hospital admissions on June 22 – a rate of 16 per 1000 new cases – compared with 3,812 admissions on January 12, the height of the second wave, a rate of 84 per 1000 new cases.
Boris Johnson’s government is currently intending to end all restriction measures on July 19, but exactly what this will mean for new cases of Covid-19, and public health, is almost impossible to predict, due to the varying degrees of immunity to the virus in the population.
“The third wave will be different in characteristics to before, but the situation is so complex to model,” says Ravi Gupta, professor of clinical microbiology at the University of Cambridge. “You have lots of vaccinated people, those who are semi-immune because they’ve already been infected, unvaccinated people, and a lot of young people.”
In addition, intensive care wards report a very fragmented picture across the UK, making it far more difficult for policymakers to form a coherent strategy. While the third wave has already intensified in the North West, where there have been 17,496 new cases over the last seven days, other regions are still seeing relatively little transmission. “Where we are, it’s fine,” says Matt Morgan, consultant in intensive care medicine at University Hospital of Wales. “Wales is doing really well. But in some areas in the North and the West Midlands, you can see this scooped out curve of hospital numbers climbing which is the big concern.”
Morgan thinks that this variation between regions is making it hard for the public, mentally fatigued by the toll of repeated lockdowns, to accept the potential threat posed by the third wave. “Waves one and two were a case of, ‘We’re all in it together,’ to some extent,” he says. “It’s not like that now, and it’s really hard for people to get the narrative that the vaccination campaign has gone so well, yet there’s still an ongoing risk.”
While the NHS continues to vaccinate the population with remarkable efficiency – as of June 22, 64 per cent of the country had received at least one dose of the vaccine – there remains a proportion of people who are not protected. Martin Landray, a professor of medicine and epidemiology at the University of Oxford, points out that there will be a percentage of elderly individuals who have not mounted a full immune response to the vaccine, while the effects may begin to wear off in others who received the jab in the early months of the campaign.
