A new analysis of practice records has confirmed concerns that Covid-19 virus flourishes in areas of dense population.

The research, published by The Lancet, also points to high prevalence in ethnic minority communities, independently of population density. Researchers analysed practice data of 3,802 people tested for the virus of which 587 had positive results. There was a negative link with smoking behaviour – but the researchers do not believe this indicates a protective effect.
As many as 62% of those from ethnic minorities who were tested were found to have positive results. The researchers say this was significant, even after adjustment for existing disease – but the findings could indicate bias in the choice of those to be tested.

Researcher Professor Simon de Lusignan, from Oxford University, said: “While clear trends have emerged from hospital data for the people with severe symptoms, the risk of infection among the general population remains a grey area. It’s important to know which groups in the wider community are most at risk of infection so that we can better understand SARS-CoV-2 transmission and how to prevent new cases.”

He added: “This result does not indicate that smoking protects against infection, and there are many potential alternative explanations – such as smoking hampering the sensitivity of the SARS-CoV-2 test, or people who smoke being more likely to have an ongoing cough so being more likely to be tested despite not having the virus. As well as the well-documented harms to overall health from smoking, there is potential for smoking to increase the severity of Covid-19 disease.”

Fellow researcher Dr Gayatri Amirthalingam, from Public Health England, said: “This analysis of primary care outcomes of individuals testing positive for virus is an important contribution to our wider understanding of how Covid-19 is affecting people of different demographic groups.”

The study was welcomed by the Royal College of GPs. Chair Professor Martin Marshall said: “The more we learn about the virus, the more accurate clinical guidance can be and the more personalised the care and advice GPs and our teams can give to patients. This will help them take the necessary precautions to keep well, based on their individual circumstances, including their age, ethnicity, medical history and social factors, and will potentially save lives.

“There are still lots of things we don’t know – specifically, why some people are more susceptible to Covid-19 than others – but having this data is an important starting point to further research that could help answer these questions. RCGP now has an active network of over 1,100 practices ready and willing to share data to answer important research questions, their contribution underpins this study.”