About
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About
The COVID Resource of CityU is a project to track the realtime local COVID19 situation in Hong Kong. It can allow researchers to observe the infection dynamics and policymakers to make better decisions to mitigate risks of community outbreaks. It was developed at the Yuan Modeling Group, Department of Biomedical Sciences, headed by Dr. Yuan.
Average Cases
Average cases are calculated as central moving averages (sliding windows) with a 7 day wide window. Therefore, for a day in the series, the number of cases is calculated as the mean of the number of cases reported in a period ranging from three days preceding the date to three days succeeding the date. \[xa_t = \frac{1}{7}\sum_{n=t3}^{t+3}x_t\]
For the first 3 days, the mean is calculated based on the following formula: \[ xa_t = \frac{1}{3+d}\sum_{n=t(d1)}^{t+3}x_t \] where d is the day (eg for the first day d = 1 )
For the last 3 days, the mean is calculated as follows: \[ xa_t = \frac{1}{3+d}\sum_{n=t3}^{t+(d1)}x_t \] where d is the day (eg for the last day d = 1 )
Definitions

Epilink :It stands for epidemiological link.
Local with Epilink refers to cases epidemiologically linked to local cases and local without Epilink refers to those local cases which are not traced to other local cases. \[ L_n = L  L_p \] where L_n stands for the number of cases without Epilink, L_p stands for the number of cases with Epilink and L stands for the total number of local cases.

Confirmation delay :
It is the average delay in reporting cases. Essentially, it is the difference between the day
of reporting a case and the day of onset of symptoms. It is only applicable for cases
symptomatic cases.
This shows the efficiency of contact tracing .
Calculating delay
Only local with Epilink and local without Epilink cases were considered.
\[adelay_t = \frac{\sum_{n=t3}^{t+3}delay_t}{\sum_{n=t3}^{t+3}cases_t}\]Where adelay_t is the average delay in time t and the cases_t is the number of cases with delay.
For each case, delay (days) = Report date – confirmation date
\[ delay = Date_r  Date_s \]And for a day, cases with delay = total cases reported – asymptomatic cases. Of course, only cases with valid date of symptom onset were considered.
Sources of data
All data is sourced from the official website of Centre for Health Protection, an agency under the Department of Health, Government of Hong Kong.
The addresses of the buildings were determined using Google Geocoding API.