Ross Clark Ross Clark

Why are Covid cases going down?

Imagine if the government had taken notice of the assorted scientists who, a couple of weeks ago, were imploring them to immediately enact ‘Plan B’ and reintroduce measures such as compulsory mask-wearing, working from home and limits on gatherings. The current dip in new Covid cases would be heralded as a sign of the success of the policy, and there would be calls for new lockdowns, or semi-lockdowns to control Covid infection numbers in the winter.

Something similar happened back in July when some scientific opinion was in favour of delaying the full reopening of the economy and society. At the time, professor Neil Ferguson warned that infection numbers would certainly hit 100,000 a day and could even reach 200,000. The government went ahead and reopened society anyway – and infection numbers began to fall almost immediately. It is perfectly reasonable to wonder whether the fall in infections which followed the lockdowns was also the result of government policy, or if it would have happened spontaneously. The Covid modelling always suggested there would be a number of sharp spikes, where infections would peak and then fall equally quickly. We will never know for sure the exact role played by lockdowns because we don’t have a control scenario: a parallel universe where lockdowns were not introduced.

So what has caused the current slide in new infections, if not ‘Plan B’? Cambridge University’s Medical Research Council’s Biostatistics Unit (MRU) comes up with an intriguing and rather dramatic estimate: that around 76 per cent of children aged between five and 14 have been infected with Covid since the start of the pandemic. If that is correct, it is little wonder that infections are now falling nationally: Britain’s population of five- to 14-year-olds must be close to reaching a state of herd immunity, and so schools are no longer likely to be great seedbeds for future waves of infection. These estimates are considerably higher than those from the ONS which found 11-13 per cent of pupils had antibodies at the beginning of July (the BSU estimated around 50 per cent in the same period).

Across all age groups, the MRU estimates that 26.3 million people in England have now been infected – equating to 47 per cent of the population. This is still lower than the level of infections the government’s scientific advisers originally estimated would be required before the country reached herd immunity. Nevertheless, it is a markedly high figure and rather confirms that we have unofficially switched to a policy of allowing the virus to spread among the population, with vaccination reducing serious illness and deaths among adults.

The MRU’s latest estimate for Covid’s Infection Fatality Rate – across all age groups – is 0.19 per cent. Only among the over-75s – who have an IFR of 3 per cent – does it exceed 1 per cent. By contrast, the Imperial College modelling of March, which suggested that up to 500,000 people could die of Covid in an unvaccinated Britain, assumed an IFR of 0.9 per cent. It seems we are finally learning to live with this virus.

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