Data released by Statistics Jersey, based on a cross-section of just over 1,000 people, also shows that 62% of those who tested positive reported no symptoms.
The latest results from the pin-prick procedure, carried out at the end of May, gave an estimated prevalence of Covid-19 of 4.2% for 20 May – this date was given in order to allow for the fact that antibodies may not be detectable for up to a week.
The approximate number of cases shows an increase from the first round of testing in early May, when an estimate of 3,300 cases was given. Statistics Jersey has stated that a change in the testing device is the likely cause of the difference.
A spokesperson for the team said that a list of 1,000 private addresses had been randomly drawn from the Jersey Land and Property Register in order to form a representative sample for the study.
A total of 629 households and 1,062 individuals took part in the testing, which focused on those aged 16 or over living in private households. The prevalence rate, in which Statistics Jersey have expressed ‘95% confidence’, was then applied to the Island’s entire population, resulting in the 4,500 figure.
A loss of taste and smell was the most commonly reported sign of the disease and was cited by 47% of those who said they had had symptoms. The other indicators, cited by 10-15% of symptomatic respondents in each case, were muscle ache, a continuous cough or fever, headaches, respiratory issues or tiredness.
Statistics Jersey said that the proportion of positive cases with no reported symptoms was 62%, a figure that was consistent with research from other jurisdictions.
The new study indicates a consistent range of positive cases among different age groups, varying between 4.3% (for 16 to 34-year-olds) and 6.7% (those aged 65 or over).
One exception to this was the 35-44 age band, with only 0.3% of tests being positive – Statistics Jersey’s spokesperson confirmed this figure, but said that the low numbers did not indicate a statistically significant difference within the age groups.
The proportion of positive tests among men (5.1%) was more than one-and-a-half times the equivalent figure for women – 3.3%. This mirrors the pattern of deaths attributed to Covid-19, with 67% of the Island’s 30 victims (including both lab-confirmed and probable cases) being male.
In addition to the government’s representative survey, Islanders have also been able to choose to pay for a test for antibodies through private provider Orchid Care Services.
A total of 1,146 tests had been carried out by Orchid, according to data published on 6 June, with antibodies relating to coronavirus detected in 11% of the samples tested.
In addition to the antibody testing that gives an estimate of how many cases there may have been throughout the period of the pandemic, swab testing to identify current cases has continued.
A total of 9,223 tests has been carried out since 12 February, including a significant increase over the past two weeks, with more than 3,300 tests conducted during that period.
Six new positive cases have been reported during the past fortnight, and the current total of known active cases of Covid-19 in Jersey is five – including one patient who is currently receiving hospital treatment.
The JEP has asked the government for information regarding the new positive cases, specifically whether they had been traced to earlier cases in private residences or care homes, or had originated from someone arriving in the Island.