PEOPLE in England who thought the pandemic was all but over had a rude awakening last week. A government scientific advisory committee said that the number of people in England admitted to hospital with the coronavirus could rise to between 2000 and 7000 a day over the next few months. That compares with just under 1000 a day presently, and a little over 4000 at the height of the second wave in January. Given that so many people have now been vaccinated against covid-19 and case numbers have recently been declining, why are predictions for winter in England so bleak?
One factor that can get overlooked is that even in places with good vaccine uptake, like the UK and parts of the US and Europe, vaccines don鈥檛 provide complete protection. There will always be three main groups who are vulnerable: those who aren鈥檛 being immunised, which at this stage in the UK mostly comprises children; those who refuse jabs; and those who have had the vaccine but it fails to protect them.
鈥淧eople forget about that, but no one ever said the vaccine was going to be 100 per cent effective,鈥� says , UK.
Advertisement
Because of these groups, modellers predicted earlier this year that as countries such as the UK emerged from lockdowns, they would see an 鈥�exit wave鈥�, as increased mixing allowed the virus to spread.
There are signs that the UK may have recently started the downward slope of such a wave. However, its trajectory was complicated by a spike in cases in July, which seems to have been triggered by people gathering inside to watch the European Football Championship.
鈥淚f you shave that off, the situation is not that complicated,鈥� says , UK. 鈥淭here was a rise in cases steadily over the summer that鈥檚 come to some sort of peak or plateau 鈥� that鈥檚 what a wave looks like.鈥�
The football tournament-related spike aside, the wave has so far been lower in height than most models predicted. This is probably because people didn鈥檛 respond to the end of lockdowns by returning to their old levels of social mixing, the SPI-M-O committee, which advises the UK government, said in , which was made public last week. 鈥淭he population has not reduced their cautious behaviours as dramatically as was considered possible,鈥� it said.
An ongoing study of behaviour by the London School of Hygiene & Tropical Medicine, called the CoMix Social Contact Survey, found that in the week ending 6 September, UK adults were having contact with an average of , compared with about 11 before the pandemic. And there is often less exposure during such contacts, for instance because people avoid shaking hands and opt to meet outdoors.
But old patterns of behaviour are returning. The survey shows that, while three-quarters of people still wear face masks, their use has been slowly declining since July.
鈥淥ver the summer, people were being quite cautious,鈥� says . 鈥淣ow people are increasingly going back to work using public transport. We start moving indoors, where we tend to be closer together in unventilated spaces.鈥�
This higher level of mixing could trigger a further exit wave, but opposing forces are at play. Factors pushing the infection rate down include a rising number of people with strong immunity to the virus, from infection, vaccination and booster jabs. But it is possible that immunity waning over time and the emergence of more infectious coronavirus variants could push rates up. Everything hinges on how these competing forces balance out, says Johnson. 鈥淭here鈥檚 immense uncertainty.鈥�
Following July鈥檚 spike, the pressures pushing infection rates up and down in England have been roughly equal, with R 鈥� the number of new infections triggered by each case 鈥� close to 1. It may not take much to nudge R back above 1 again though, and if a factor like waning immunity causes it to hit 1.5, it could lead to 7000 hospitalisations a day. But the committee didn鈥檛 say this would definitely happen 鈥� only that it is a possibility. A scenario in which R hits 1.1 and leads to 2000 hospitalisations a day is more likely, according to the group鈥檚 modelling.
鈥淵ou could make a strong case that from now on, you expect the number of cases to go up or to go down or to stay the same,鈥� says Woolhouse. 鈥淭hat means you have to be prepared for a set of eventualities. You could encapsulate them as: hope for the best, but prepare for the worst.鈥�
