Statistics Jersey have today published the results of the second round of the community antibody testing program. This is a survey of Islanders using rapid test kits in order to estimate the prevalence of SARS-CoV-2 related antibodies in the Jersey population.
Our key finding is that the estimated population prevalence rate of SARS-CoV-2 antibodies is:
4.2% ± 1.3 pp (95% confidence interval)
This prevalence rate is for the adult resident population living in private households in Jersey. The survey did not perform testing on any person aged under 16 years and did not include residents of communal establishments (such as care homes).
Caution should be used when comparing these results with those previously published in the first round of this study, as the testing device has been changed between rounds of the survey. Whilst efforts have been made to account for differences in sensitivity and specificity between the two devices, this should still be noted when considering the results.
It is also important to note that there remains a degree of uncertainty in the performance characteristics of the devices. This uncertainty is not reflected in the above confidence interval.
The estimated prevalence rate implies that the total number of cases of SARS-CoV-2 that have occurred in households living in private accommodation was approximately 3,600. Whilst it is anticipated that there may be differences between this population and those who were excluded from this study, applying the estimated prevalence rate to the full Island population would equate to approximately 4,500 cases having occurred to date.
Due to the initial lag between infection and antibodies becoming detectable, some cases in their early stages of infection will not be detected. The resultant prevalence rate should, therefore, be considered as the prevalence as of around 20th May 2020.
Whilst there exists a degree of uncertainty around these figures, the results of this analysis, and the above prevalence rate, are in line with the ongoing epidemic modelling currently being conducted.
Additional analysis is provided by demographic breakdowns, as well as details on prevalence rates that correspond to reported symptoms. Of particular note is that this study does provide evidence that a high proportion of asymptomatic cases have taken place in Jersey. Indeed 62% of those who tested positive for SARS-CoV-2 related antibodies, reported no history of any symptoms. This behaviour is consistent with other emerging research on SARS-CoV-2 from other jurisdictions.