Table 2. SARS-CoV-2 positivity, underdetection and undernotification among participants from two administrative areas of Port Vila, Vanuatu, April 2022.

Outcome	n	%	95% CI
SARS-CoV-2 positivity
Attack rate (point prevalence)	89	50.9a	43.2–58.5
Cumulative attack rate	104b	55.3c	47.9–62.6
SARS-CoV-2 underdetection
Number of positive participants that were not detected before the study   (self-reported and verified)	89	85.6d	77.3–91.7
SARS-CoV-2 notification rate
Participants self-reporting previous positive test result	23	9.2e	3.2–15.1
Participants self-reporting previous positive test result with corresponding notification to surveillance unit	15	65.2f	49.4–81.0
SARS-CoV-2 testing
Participants reporting having had a specimen tested for SARS-CoV-2 during   the previous month	31	12.3e	5.4–19.2
Positive participants reporting having had a specimen tested for SARS-CoV-2 during the previous month	22	20.4d	11.5–29.2
Household attack rate
Number of households with at least one case	50	59.5f	44.4–74.6
Secondary household attack rate	–	47.7g	34.2–61.2

CI: confidence interval; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2.

^a Denominator includes all 175 participants who had a specimen collected in the study.

^b Numerator includes 89 participants detected in this study plus 15 participants with verified previous infection.

^c Denominator includes 188 participants with known SARS-CoV-2 test result, excluding those with no testing history.

^d Denominator includes all 104 SARS-CoV-2-positive participants.

^e Denominator includes all 252 participants.

^f Denominator includes all 84 households.

^g Rate is only calculated for 50 households with at least one case.