Table 3.

Estimates of the hidden prevalence of COVID-19 in Ireland from 1 March to 19 October 2020 using the back-calculation method with a Gamma incubation period distribution $\mathbf{\Gamma }(3·0,0·45)$ and $\mathbf{\Gamma }(2·0,\hspace{1em}0·30)\left[\mathrm{AQ}10\right]$

Epidemic wave	Hidden prevalence, $C_U\left(t\right)$ given alpha =3	Known diagnosed prevalence, $C_T$	Estimated total prevalence	Ratio of unknown cases to each known case
Wave 1, increasing phase 1 March–16 April	15 197	12 547	27 744	1.2–1
Wave 1, decreasing phase 17 April–31 May	9748	12 382	22 130	0.8–1
Wave 2, increasing phase 1 June–19 October	24 312	24 747	49 059	1.0–1
1 March–19 October	49 257	49 676	98 933	1.0–1
Epidemic wave	Hidden prevalence, $C_U\left(t\right)$ given alpha =2	Known diagnosed prevalence, $C_T$	Estimated total prevalence	Ratio of unknown cases to each known case
Wave 1, increasing phase 1 March–16 April	15 120	12 547	27 667	1.2–1
Wave 1, decreasing phase 17 April–31 May	9610	12 382	21 992	0.8–1
Wave 2, increasing phase 1 June–19 October	24 203	24 747	48 950	1.1–1
1 March–19 October	48 933	49 676	98 609	1.0–1

Note: Significance of bold values indicates total prevalence of all epidemic waves.