Question to the Department of Health and Social Care:

To ask the Secretary of State for Health and Social Care, what the evidential basis is for the decision to change the NHS Covid App’s operational rules to reduce the time period to notify contacts from within five days to within two days of asymptomatic cases testing positive; and what estimate he has been made of the scale of the consequential reduction in notifications from that change.

For people who tested positive for COVID-19 but did not have symptoms, it is difficult to know when the period of infectiousness started. Someone without symptoms may have been tested at any point between the start and end of their period of infectiousness. Advice from Public Health England, taking into account operational, clinical and other factors, is that the highest risk period for contacts is most likely to be two days from the test date, this is in line with standard contact tracing practice. The NHS COVID-19 app has therefore been updated to look back two days from the positive test date for contacts of cases who had no symptoms. This change strikes a balance between protecting public health and reducing potential social and economic disruption. The anonymous nature of the app means it is not possible to robustly calculate what impact this change will have, however we are confident this will significantly reduce the number of low-risk contacts being advised to self-isolate.