Positive Covid-19 cases with unknown source (FOI)

Request

A

Please may I have the number of cases of Coronavirus (positive test) since 1 October 2020 where the source of the infection remains unknown? I.e. not via a known contact or a travel infection.

B

Can these statistics be published as part of the spreadsheet data?

C

What processes are used to try and track the source of the infection?

D

What informs the decision that no further searching should take place?

Response

A

It is not possible to provide accurate information on the number of cases that have an unknown source. This is because the team constantly review cases to determine whether there is a link to a cluster or premises.

As at 6 November 2020, the Deputy Medical Officer of Health provided information in a press conference regarding the number of positive cases which, at that time, had an unconfirmed source. This was:

Incidents of unknown source

B

The fluidity of the investigations means that information may be out-of-date very soon after it has been produced. We are reviewing what information is provided on our Covid-19 statistics page and will consider this request.

C

Once a positive case has been identified, the Contact Tracing team work with the individual to identify their Direct Contacts, by speaking with them about where they have been, who they have seen, what transport they have used, where have they shopped and any other questions needed to identify their movements. We start with the 72 hours prior to their swab / onset of symptoms but can go back as far as 10 days to identify their history and who may be a direct contact. These initial calls can sometimes take up to three hours, as they are extremely detailed.

In addition, if the individual has been in an enclosed premises, for example a restaurant or bar, or on a ferry or aeroplane, we gather information about the other customers in that vicinity at the same time. Where appropriate those individuals are contacted as Direct Contacts, or, should the risk increase, as Indirect Contacts who are then offered a screening test.

The Analytical Cell, which meets daily, includes the Deputy Medical Officer of Health, Policy colleagues and Informatics colleagues. The Cell reviews all positive cases, their Direct Contacts and their possible linkages. Taking a scientific approach, informed by medical advice, helps to identify possible clusters and transmission, and aims to identify the source of the transmission, by identifying the initial positive case.

D

Direct Contact searching ceases when we are confident that every possible avenue has been explored from the positive case and each of their Direct Contacts. As explained above, detailed discussions are held with each positive case. Similar discussions are also held with everyone identified as a Direct Contact, as they may identify different individuals who are Direct Contacts of the original case.