Table 2.

Epidemiological indicators by epidemic wave.

Indicators	Epidemic waves and periods
	1					2		3	4
	A	B	C	D	E	F	G	H	I
Case details
Number of cases	250	28,181	3,870	32,617	13,563	3029	2150	15,308	580
Relative percentage of casesa	0.3	28.3	3.9	32.8	13.6	3	2.2	15.4	0.6
Num. of cases with positive culture	0	69	0	12	109	8	0	16	5
Num. of cases with positive RDTb	99	3398	6	569	1183	106	0	59	0
Number of woredas ≥ one case reported	6	407	61	127	237	62	78	71	3
Number of woredas ≥ 10 cases reported	2	237	24	72	129	21	35	53	3
Number of woredas ≥ 50 cases reported	2	108	8	56	56	9	15	40	3
Percentage of number of woredas ≥ 50 casesc	33.3	26.5	13.1	44.1	23.6	14.5	19.2	56.3	100.0
Population exposed	641,000	46,295,300	5,599,600	13,302,000	24,131,500	4,236,900	11,414,300	6,263,900	337,200
Attack rate per 10,000 pop	3.9	6.09	6.91	24.52	5.62	7.15	1.88	24.44	17.2
Start week–end week period	W37 2015–W04 2016	W05 2016–W47 2016	W48 2016–W04 2017	W05 2017–W20 2017	W21 2017–W46 2017	W21 2018–W01 2019	W17 2019–W50 2019	W51 2019–W09 2021	W35 2021–W51 2021
Duration in weeks	21	43	9	16	26	33	34	64	17
Standardized attack rate (10,000 pers−1.week−1)	0.19	0.14	0.77	1.53	0.22	0.22	0.06	0.38	1.01
Death details
Number of deaths	2	182	14	46	101	33	24	228	7
Relative percentage of deaths	0.3	28.6	2.2	7.2	15.9	5.2	3.8	35.8	1.1
Number of woredas ≥ one death reported	2	74	5	15	46	9	15	37	2
Overall case fatality ratio	0.80	0.65	0.36	0.14	0.74	1.09	1.12	1.49	1.21
Case fatality ratio median (percentage) d	0.84	2.37	1.42	1.47	2.41	2.38	2.04	1.9	1.68
Case fatality ratio minimum–maximum (percentage)d	0.79–0.9	0.07–50	0.23–6.67	0.06–20	0.17–33.33	0.88–10	0.47–100	0.42–14.29	1.13–2.22

^aThe relative percentage is calculated over the entire 2015–2021 study period.

^bRDT: Rapid diagnostic test.

^cThe denominator corresponds to the number of woredas with at least one case reported.

^dThe denominator corresponds to the number of woredas with at least one death reported.