This morning we have some data giving a little more insight into the great unknown of the coronavirus pandemic: just how widely among the population has SARS-CoV-2 – the virus which causes Covid-19 – spread among the general population. A team at the University of Bonn has tested a randomised sample of 1,000 residents of the town of Gangelt in the north-west of the country, one of the epicentres of the outbreak in Germany. The study found that two per cent of the population currently had the virus and that 14 per cent were carrying antibodies suggesting that they had already been infected – whether or not they experienced any symptoms. Eliminating an overlap between the two groups, the team concluded that 15 per cent of the town have been infected with the virus.
This number matters hugely because it tells us what we need to know in order to judge how deadly the virus is and also how easily it spreads. It tells us, ultimately, how useful the methods are that we are employing in order to combat the virus. As explained here before, the question of how many people already have the infection is at the heart of a debate between epidemiologists at the Imperial College and Oxford university.
Two weeks ago, the latter published modelling claiming that up to half the UK population might already have been infected with the virus – a level of infection which would mean that lockdown may be the wrong approach, as we would already have achieved a state of herd immunity, preventing the further spread of the disease.
The Gangelt study does not provide support for the idea that half of the population of Britain, or any other country, has been infected with the virus.