## Finland

### NOTE

Here the dates are those when the covid-test is taken but many sources report the date when the test result is confirmed positive. This makes the numbers differ slightly.

Aug 6th: The data has up to one-week delay due to jammed testing centers and labs. See, e.g., hs.fi and aamulehti.fi.

## Finnish University Hospital Catchment Areas

Finland has five university hospitals which provide advanced treatments needed for serious COVID-19 cases. In the following, we provide data on the regions for which the university hospitals are responsible.

## HYKS

### NOTE

Here the dates are those when the covid-test is taken but many sources report the date when the test result is confirmed positive. This makes the numbers differ slightly.

Aug 6th: The data has up to one-week delay due to jammed testing centers and labs. See, e.g., hs.fi and aamulehti.fi.

## TAYS

### NOTE

Here the dates are those when the covid-test is taken but many sources report the date when the test result is confirmed positive. This makes the numbers differ slightly.

Aug 6th: The data has up to one-week delay due to jammed testing centers and labs. See, e.g., hs.fi and aamulehti.fi.

## OYS

### NOTE

Here the dates are those when the covid-test is taken but many sources report the date when the test result is confirmed positive. This makes the numbers differ slightly.

Aug 6th: The data has up to one-week delay due to jammed testing centers and labs. See, e.g., hs.fi and aamulehti.fi.

## TYKS

### NOTE

Here the dates are those when the covid-test is taken but many sources report the date when the test result is confirmed positive. This makes the numbers differ slightly.

Aug 6th: The data has up to one-week delay due to jammed testing centers and labs. See, e.g., hs.fi and aamulehti.fi.

## KYS

### NOTE

Here the dates are those when the covid-test is taken but many sources report the date when the test result is confirmed positive. This makes the numbers differ slightly.

Aug 6th: The data has up to one-week delay due to jammed testing centers and labs. See, e.g., hs.fi and aamulehti.fi.

## Data sources

The number of confirmed cases is fetched daily from THL's public API. The ward occupancies are obtained from HS's data source.

Note that daily confirmed cases from THL is set to have a two-day delay due to large uncertainty in the reported cases.

## Estimation of Rt

The time-dependent reproduction number Rt is estimated from the daily number of confirmed cases using Bayesian smoothing. We set up a simple SEIR model, \begin{align} S(t+1) &= S(t) - \frac{R_t(t)}{T_i} I(t) \frac{S(t)}{N} + \omega_S \\ E(t+1) &= E(t) + \frac{R_t(t)}{T_i} I(t) \frac{S(t)}{N} - \frac{1}{T_e} E(t) + \omega_I \\ I(t+1) &= I(t) + \frac{1}{T_e} E(t) - \frac{1}{T_i} I(t) + \omega_I \\ \text{recovered}(t+1) &= \text{recovered}(t) + \frac{1}{T_i} I(t) + \omega_{\text{recovered}}\\ R_t(t+1) &= R_t(t) + \omega_{R_t}, \end{align} where $$R_t$$ is now also a state variable, and $$\omega$$s are small Gaussian noises except for $$\omega_{R_t}$$ for which we have the variance 0.00025.

The measurement model is \begin{align} \text{Daily New Cases} &\sim \frac{R_t(t)}{T_i} I(t) \frac{S(t)}{N} + \omega_z. \end{align}

The system state is estimated using an unscented Rauch-Tung-Striebel smoother.