An analysis published by a mathematician suggested the UK infection peak was March 18-19 has been seized upon by those opposed to lockdown – but another expert isn’t so sure. Tony McDonough reports
Since Prime Minister Boris Johnson announced the UK lockdown on March 23 there has been a fierce debate between strong supporters of the policy, who claim it should have been implemented earlier, and those who says lockdown wasn’t necessary at all.
As has happened so many times during this pandemic, complex data has been over-simplified by those who wish to push a specific agenda. And it seems this may be true of a study published a few days ago.
Simon Wood, a mathematician at Bristol University, calculated that the peak of UK infections likely occurred a few days before we locked down. It could be said to suggest that the call on March 16 for us to socially distance and wash our hands frequently was enough to halt the spread of the coronavirus epidemic.
His calculations are based on the fact that UK COVID-19 deaths peaked on April 8/9 when more than 2,000 people died. Based on a median time of infection-to-death of around 23 days, Mr Wood puts the virus peak at around March 18-19.
His calculations were seized upon by people opposed to the lockdown who believe the economic and social damage far outweigh the benefits. So does Mr Wood’s data prove them right?
Not quite, says Adam Kucharski, a mathematician/epidemiologist at the London School of Hygiene and Tropical Medicine, and author of ‘The Rules of Contagion’. He implies the interpretation of Mr Wood’s analysis has been simplistic.
Professor Kucharski points out that the flattening of the epidemic required multiple measures and that a lockdown is not a “simple on/off binary measure”.
He explains: “First, as Wood notes, it’s extremely difficult to estimate a definitive date of infection peak, given limited surveillance data from this period.
“The analysis suggests UK infections peaked around March 18-21. For context, schools, pubs, clubs, gyms, restaurants etc, were ordered to close on the 20th. But this doesn’t necessarily mean that measures introduced after the peak had no effect.
“At an epidemic peak the growth rate is zero. If no further decline had happened, the epidemic would have stayed at this level, in this case at around 2,000 estimated fatal infections per day.”
Prof Kucharski adds that it means without lockdown, the UK infection rate may have declined more slowly than with lockdown, potentially leading to an even higher number of deaths.
Looking at Mr Wood’s research, Prof Kucharski estimates the fastest rate of post-peak decline was probably happening around March 24-26, after the lockdown.
“Different countries have used different combinations of measures, introduced in different sequences, against a background of different outbreak dynamics,” he said. “Understanding the most effective and efficient way to maintain ongoing control in future will therefore be crucial.”