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Analysis of the proportion of people testing positive, the rate of new infections and the proportion of people with antibodies for COVID-19 for 29 June to 2 August 2020.

The COVID-19 Infection Survey (CIS) aims to establish:

  • how many people have the infection over a given time
  • how many new cases occur over a given period
  • how many people are likely to have been infected at some point

The survey will help track the current extent of infection and transmission of COVID-19 among the population as a whole. As well as looking at incidence overall, the survey will be used to examine the characteristics of those testing positive for COVID-19 and the extent to which those infected experience symptoms.

Fieldwork started in Wales on 29 June 2020 and the first results are now available. It is important to note that there is a significant degree of uncertainty with the estimates. This is because, despite a large sample of participants, the number of positive cases identified is small. Estimates are provided with 95% credible intervals to indicate the range within which we may be confident the true figure lies.

The results are for private households only and do not apply to those in hospitals, care homes or other institutional settings.

The first results for Wales show that for the week of 27 July to 02 August 2020 it is estimated that an average of 0.05% of the population had COVID-19 (95% credible interval: 0.01% to 0.11%).

This equates to around 1 in 2,200 individuals within the community population in Wales (95% credible interval: 1 in 7,800 to 1 in 900), or an estimated 1,400 people in Wales in total (credible interval: 400 to 3,400).

Further analysis will be possible as the survey progresses and more data are available. We intend to publish estimates for incidence (the number of new infections per 10,000 people) and the proportion of people with antibodies to COVID-19 when the data support this level of analysis.


Gowan Watkins

Telephone: 0300 025 6340

Rydym yn croesawu galwadau a gohebiaeth yn Gymraeg / We welcome calls and correspondence in Welsh.


Telephone: 0300 025 8099

Rydym yn croesawu galwadau yn Gymraeg / We welcome calls in Welsh.