Covid: why has the fall in UK infection rate stalled despite vaccinations?
The UK’s Covid-19 statistics remain encouraging despite continuing rows over vaccine deliveries in Europe. Admissions to hospital and daily deaths from the disease continue to decline with numbers in the latter category now down to double digits while the former have dropped to around a 10th of their total two months ago.
However, one other category – numbers of new diagnoses a day – has reached a plateau with cases, having plunged from 60,000, stabilising at around 5,000 to 6,000. So why has this figure apparently stalled while deaths and hospitalisations continue to decline?
The reason is straightforward, say scientists. The vaccine has been targeted so that the most vulnerable – the elderly in particular – were given jabs before others and this is now having an impact on deaths and hospital admissions.
“Because the vaccine has had a very high uptake in the age groups which are most likely to go to hospital or to die, then we would expect – even if the number of infections stayed the same – hospitalisations and deaths to fall,” said Steven Riley, a professor of infectious disease dynamics at Imperial College London.
Those who are vulnerable – mainly because of their advanced age – are being protected by vaccines and so deaths and hospital admissions are declining. Younger people – who have yet to be vaccinated but who are thought to be responsible for most transmission – are continuing to spread the virus, though this transmission is being limited by lockdown.
“Now that the schools have reopened, we could see a rise in case numbers – as was seen in Israel,” added Riley. “When they opened up after their vaccination programme was well under way, they did have a little upswing in cases and hospitalisations but it was very short lived. Very quickly it started to go down again. So at the moment, the data from Israel looks encouraging.”
However, Riley warned that new variants might alter the position in the UK and trigger some rises in case numbers. “On the other hand, the data in the UK since Christmas is positive. It is looking very good at the moment but we will have to keep on monitoring cases, on a regional basis, to continue to check for the appearance and possible spread of new variants.”