New COVID-19 cases definition to include multiple infection episodes from 31 January 2022

Date published: 27 January 2022

Reinfections have previously been included in daily updates of new COVID-19 cases, but re-infections were only counted once in cumulative totals.

On the dashboard, the change means:

• cases by report date will change to the new definition of an episode of infection
• historical numbers by report date will not be revised, so there will be a step increase in the cumulative numbers of cases on that date
• specimen date metrics will be revised back to the beginning of the pandemic, in the dashboard graphs showing trends
• the same metric names will still be used
• new metrics will show first episodes of infection and episodes of reinfection, shown by specimen date only

The Department is working with the UKHSA and other devolved administrations to align definitions across the UK.

Additional details

As the pandemic continues and more variants emerge, it is more likely that people will be reinfected with COVID-19. Contact tracing and health protection work at PHA follows up people with a positive test result, whether they were a new case or a case of reinfection. However, surveillance figures only report COVID-19 cases as the date of the most recent infection, so individuals are only counted once.

UK public health agencies are now updating surveillance data to count infection episodes, including reinfection episodes. Infection episodes will be counted separately if there are at least 90 days between positive test results. Each episode begins with the earliest positive specimen date. If someone has another positive specimen within 90 days of the last one, this is included in the same episode. If they have another positive specimen more than 90 days after the last one, this is counted in a separate episode (a possible reinfection episode).