Published: 16:40, 17 January 2021
| Updated: 16:42, 17 January 2021
More than half of people living in Folkestone and Hythe could have already had Covid, according to scientists.
Earlier this month we revealed how experts at the University of Kent estimated that as many 30% of residents across the county had contracted the virus since the pandemic struck.
That upper estimate has now increased to 37% - 689,200 people - but in some areas of Kent the ratio is much higher.
Bioscientists say as many as 56% of residents in Folkestone and Hythe have caught Covid-19 - despite just 6% testing positive for the virus,
Prof Martin Michaelis and Dr Mark Wass, from the university's School of Biosciences, say the number of positive tests recorded is not a reliable indicator of true infection rates as there are many cases that are never formally diagnosed, especially in people without symptoms.
They instead say they can make a “reasonable estimation" using the Covid infection-fatality rate, which correlates the number of deaths with the true number of cases.
“Deaths are hardly ever missed,” the say, “and there are reliable data that estimate the infection-fatality rate for Covid-19, i.e. the percentage of infected people that die from the disease, is between 0.5% and 1.5%."
Using this range, between 229,733 and 689,200 of Kent’s residents could have already had Covid, while the number of confirmed positive tests has just passed 119,000.
This accounts for between 12% and 37% of the county’s population.
In Folkestone and Hythe, there have been 6,580 positive tests, but the scientists estimate the true figure to be between 21,333 and 63,400.
The higher figure is equivalent to 56% of Folkestone’s population.
Applying the same method across the county, the next worst-hit would be Thanet, with 44%, and Dover, with 43%.
How did the scientists calculate the estimated total number of Kent Covid infections?
Prof Michaelis and Dr Wass say the standard approach would be to find out how many people have antibodies. But current systemic data on this is not available.
They say Covid-19 antibody levels appear to decrease quickly "in a significant fraction of Covid survivors".
Meanwhile, the number of positive tests recorded is not a reliable indicator, so they use the total number of deaths to calculate what they say is a truer figure.
According to the most recent figures, there have been 3,446 Covid deaths in Kent and Medway.
For an infection-fatality rate of 1.5%, this results in 229,733 infections (12% of the Kent and Medway population). For an infection-fatality rate of 0.5%, this results in 689,200 infections (37% of the population).
The average infection-fatality rate in high-income countries like the UK is 1.15%, according to researchers from Imperial College London.
Under this measure, about one in six people (16%) in Kent and Medway would have already caught coronavirus.