The Guardian Weekly

A race against time

Has the UK finally got the measure of Covid-19?

By Robin McKie

John Edmunds has been at the centre of the unravelling of the Covid-19 pandemic since cases first appeared in January 2020. A member of Sage, the UK government’s scientific advisory group, he has consistently warned ministers about the threats posed by the disease. These risks have often been clear in their nature. But now, 18 months after Covid-19 first appeared, he believes the nation stands at a point of maximum uncertainty.

“At any other point of the epidemic, it has been easier to foresee what might happen,” he said. “But at this point, I think it’s really hard to understand what has happened and what is going to happen in the long term. There is a huge amount of uncertainty about the disease at the moment.”

The fact that the UK is a year and a half into the pandemic and still being wrongfooted by Covid-19 may seem surprising. After all, we have developed powerful vaccines to protect against it and pinpointed critically important drugs to treat patients. Science has worked wonders.

Nevertheless, researchers are still unsure about how Covid-19 will progress in the coming months. The statistics have certainly been startling. First, case numbers rocketed at the beginning of July. Then they reversed and began to fall, leaving statisticians and scientists struggling to make sense of the fluctuating figures. For good measure, a host of conflicting factors has been put forward to explain Covid case numbers.

Has the opening up of England on 19 July had a major impact? Did the Euro 2020 football tournament propel the virus through homes and pubs? Could the UK be approaching herd immunity? And what impact have school holidays had?

Untangling these factors, as well as understanding the exact impact of vaccines, has become a complex, urgent business. “It will tell us just how bad things are likely to get when society really opens up in September and October and as [the northern hemisphere] winter approaches,” said Edmunds.

There is clear agreement on one factor, however. All the evidence indicates that vaccines are playing a pivotal role in controlling the disease. But just how far has vaccine protection reached? A key factor is the degree to which the UK has achieved herd immunity. In other words, will we have reached the point where so many people have been infected or vaccinated – and therefore possess some immunity to the disease – that viral transmission falls or even stops?

“You can run some very simple models to see if the case numbers that we saw earlier this month are consistent with effective herd immunity,” said Prof Mark Woolhouse of Edinburgh University. “And in my view the answer is, yes, it is. There are some big caveats but the bottom line is that those figures are consistent with the impact of herd immunity.”

Woolhouse pointed to a recent Office for National Statistics survey that showed that about 90% of adults in the UK possessed Covid antibodies, which indicates that they could be capable of some kind of immune response to infection. “That is a

very large fraction and it may well be having an impact,” he said.

But if we are nearing this soughtafter goal, why was there such a rapid rise in cases in mid-July? Scientists point to two key factors: the Euros and schools closing for the holidays.

“If you look at herd immunity, you would expect it to peak at different times in different parts of the country as there are differing levels of immunity across the country,” said Edmunds. “But this is not what we saw: we saw a synchronous drop in cases right across England. This suggests an external factor was behind it.”

And the two most likely candidates, he said, are schools closing and the “pingdemic” that occurred immediately after the Euros. The large gatherings of fans – mostly male – in pubs to watch England, Scotland and Wales play football would have triggered jumps in case numbers in mid-July. This would have been followed by a rise in contacts asked to self-isolate.

“This bout of self-isolation occurred across the country at the same time, and it looks like it reduced cases,” Edmunds said. “But these would be expected to go up again – if were not for the effect of school closures. Pupils are no longer bringing home viruses after picking them up in class.”

Prof James Naismith, director of the Rosalind Franklin Institute in Oxford, also thinks the short-term picture is optimistic, but warned that problems will return in September when children go back to school, businesses open up and people spend more time indoors. “We will still have high levels of infection in the community. About one person in 65 carries the virus at present, and that means virus levels are not going to go down significantly by September,” Naismith said. “Under those circumstances, the virus will have a good platform from which to start infecting those who are unprotected when conditions make it more favourable for it to spread.”

One solution proposed by Naismith is to vaccinate 16 and 17-year-olds across the UK. That would protect them from Covid-19 complications, which are worse than any vaccine complications they might encounter. It would also push the population closer to the level it needs to achieve herd immunity.

Two further vexing issues bedevil attempts to clarify the UK’s route out of the pandemic: new variants and possible fading vaccine efficacy. The danger posed by new variants is raised by Jeremy Farrar, director of the Wellcome Trust, in Spike: The Virus v the People, his new book about the pandemic. High infection rates raise the chances of a new variant being cooked up, he argues. “That is very probably why the variants of concern have been traced to countries like the UK, South Africa and Brazil, which have had poorly controlled transmission.”

Scientists and pharmaceutical companies are working on vaccines to tackle some of the new variants that have appeared. For example, the Oxford vaccine team led by Dame Sarah Gilbert is working on one for the Beta variant, first identified in South Africa, which is considered to have the greatest potential to evade vaccines.

And then there is the issue of vaccine efficacy. Studies have shown that Covid-19 antibodies decrease over time. This may limit people’s protection against the virus. A study published last week indicated that the efficacy of the Pfizer vaccine declines by an average of 6% every two months. Findings such as these suggest the government may have to set up a programme of booster vaccine shots for the over-50s to strengthen their protection over the winter.

These fears were highlighted last month by the Academy of Medical Sciences: “Whether overall figures go up or down slightly, the current situation is that we’ve got an awful lot of infection around with a very transmissible variant. So the take-home message is clear: this pandemic has not yet gone away … the only thing that is clear is that the situation is very uncertain.” Observer

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2021-08-06T07:00:00.0000000Z

2021-08-06T07:00:00.0000000Z

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