To ask Her Majesty's Government, further to the statement by the Secretary of State for Transport that "due to the incubation period of this disease, and even using highly accurate tests, the capture rate of those carrying COVID-19 may be as low as seven per cent" on 7 September (HC Deb, cols 366–7), what scientific evidence was used to calculate the capture rate; what is the period to which that capture rate applies; and what assessment they have made of the utility of using tests to identify potentially infected (1) staff, or (2) visitors, before they enter nursing homes.
The assessment of the capture rate was made from a mathematical model developed by Public Health England (PHE). The 7% capture is for those infections in asymptomatic travellers that were infected before travel and were incubating infection during travel.
This finding is for asymptomatic travellers irrespective of the prevalence of infections in the country that the traveller is arriving from and is independent of the period of the year that it is applied to. This is based on the high sensitivity and specificity of current laboratory-based Polymerase Chain Reaction (PCR) and PHE has not identified any technology that has better detection rates that would change these findings.
Testing in care homes is an important part of keeping staff and residents safe in the COVID-19 response. It means those who test positive can be isolated, reducing the number of people who can spread the virus and protecting the most vulnerable.
PHE has conducted a number of prevalence studies in health care workers using reverse transcription-PCR which informs assessment of potentially infected staff. The assessment of the risk posed by visitors to care-homes is part of the SAGE social-care sub-group’s purview and will be reported in due course.