Memorial University of Newfoundland and Labrador, Canadian Network for Modelling Infectious Disease, Mathematics for Public Health, One Health Modelling Network for Emerging Infections



For current analysis, please see HERE.



Archived analysis (data prior to March 11, 2022)

The analyses below use data prior to March 11, 2022, when more information was reported.

Figure A1. Reported new cases (left) and percent positivity (right) from two public data sources. The data sources are the Department of Health and Community Services Public Advisories (aqua) and the Newfoundland and Labrador COVID-19 Pandemic Update Hub (blue). In mid-January, hundreds of test results completed out-of-province were reported. For the Department of Health and Community Services Public Advisories data (manually curated) these cases were assigned to the day they were reported.


Figure A2. Reported (symbols) and total (line) active cases as a percentage of the population of Newfoundland and Labrador. The number of unreported cases is estimated using the geometric mean method (see Methods). This method considers both the number of new cases, and the percentage of results that are positive. Reported active cases are calculated by assuming that reported new cases are active for the next 7 days. Colours denote two different data sources (as described in the Figure A1 caption).


Figure A3. The number of unreported cases per reported case. The geometric mean method (coloured lines; described in the Methods) is compared to other estimates: K-12 RAT survey is rapid antigen testing of K-12 students performed on January 22 and 25 (see Hurford (2022)); CITF pre-Omicron is an estimate from the COVID Immunity Taskforce for Atlantic Canada prior to the establishment of the Omicron variant; Hospital admissions (low) and (high) are values given by Dr. Fitzgerald during media briefings from testing of all hospital admissions. Colours denote two different data sources (see Figure A1 caption).


Figure A4. Reported (symbols) and total (line) active cases as a percentage of the population of each Regional Health Authority. Data are from the Newfoundland and Labrador COVID-19 Pandemic Update Hub as the public advisories do not report test numbers for each Regional Health Authority. See Figure A2 caption for additional details.

For Newfoundland and Labrador, I estimate \(R\) = 1.1 secondary infections per infected person when considering data from the last 10 days. The doubling time is 13 days. For methodological details, see Methods.


Methods

Geometric mean method I estimate the prevalence of unreported cases 7 days ago as approximately the geometric mean (\(n = 0.54\)) of the per capita reported new cases (14-day rolling average), and the proportion of tests that are positive (14-day rolling average; see Chui and Ndeffo-Mbah (2021) for details). The value of \(n\) is 0.54 (\(n=0.5\) is the geometric mean) and the lower and upper estimates are 0.46 and 0.67 (see Table 2 of Chui and Ndeffo-Mbah (2021))

Estimating \(R\) I estimate \(R\) using the equation, and Omicron household generation interval estimates (mean and standard derviation), from Abbott et al. (2022). I estimate \(r\) by fitting an exponential function to the reported new cases the using Department of Health and Community Services Public Advisories data over the last 10 days.