Supplementary appendix
This appendix formed part of the original submission and has been peer reviewed.
We post it as supplied by the authors.
Supplement to: Jefferies S, French N, Gilkison C, et al. COVID-19 in New Zealand
and the impact of the national response: a descriptive epidemiological study.
Lancet Public Health 2020; published online Oct 13. https://doi.org/10.1016/S2468-
2667(20)30225-5.
1
SUPPLEMENTARY
APPENDIX
Table of Contents
Supplementary Table 1: Sensitivity analysis showing features of New Zealand's national COVID-19
epidemiology and response performance over five phases of the study period for confirmed cases only…….2
Supplementary Table 2: Characteristics of COVID-19 cases associated with severe disease outcomes……..4
Supplementary Table 3: Incidence rates of testing per 100,000 person-days at risk in New Zealand over the
study period and by response phase, stratified by population characteristics: sex, ethnicity, age group,
NZDep quintile and District Health Board residence………………………………………………………….6
Supplementary Table 4: Distributions, Maximum Likelihood Estimates with bootstrapped 95%
uncertainty intervals for key time-to-event measures for COVID-19 cases in New Zealand by response
phase………………………………………………………………………………………………………………8
Supplementary Figure 1: Individual symptoms and selected symptom combinations among COVID-19
cases in New Zealand……………………………………………………………………………………...…….10
Supplementary Figure 2: Further features of the New Zealand COVID-19 response timeline……………..11
Supplementary Figure 3: Key time-to-event intervals by response phase……………………………………12
2
Supplementary Table 1: Sensitivity analysis showing features of New Zealand's national COVID-19 epidemiology and response performance over five phases of the
study period for confirmed cases only
Total
Phase 1
2 Feb to 15 Mar
Phase 2
16 Mar to 25 Mar
Phase 3
26 Mar to 10 Apr
Phase 4
11 Apr to 27 Apr
Phase 5
28 Apr to 13 May
EXPOSURE PERIODS
*
New Zealand acquired infection
†
Average estimated daily case infection
rate, cases/day (95% CI)
..
3·6 (3·0–4·3)
31·4 (27·7–35·5)
8·4 (6·9–10·1)
1·4 (0·9–2·2)
0·3 (0·1–0·8)
Average estimated daily case infection
rate, cases/million/day (95% CI),
..
0·7 (0·6–0·9)
6·3 (5·6–7·2)
1·7 (1·4–2·0)
0·3 (0·2–0·4)
0·1 (0·0–0·2)
% rate change from previous phase
..
..
770%
-73%
-83%
-78%
Source of infection, Total n (%)
1153
100
403
100
543
100
174
100
26
100
6
100
Imported case, n, % (95% CI)
520
45 (42–48)
248
61 (56–67)
229
42 (38–47)
40
23 (17–31)
2
7·6 (1·4–33)
1
9·1 (0–100)
Import-related case, n, % (95% CI)
314
27 (25–30)
80
20 (16–25)
175
32 (28–37)
55
32 (24–40)
3
12 (3·6–32)
0
..
Locally-acquired case, n, % (95% CI)
319
28 (25–30)
75
19 (15–23)
139
26 (22–30)
79
45 (37–53)
21
80 (58–92)
5
89 (0–100)
High risk worker, Total n, % (95% CI)
168
15 (13–17)
40
9·9 (7·1–14)
67
12 (9·7–16)
46
26 (20–34)
12
45 (26–66)
3
50 (15–85)
Healthcare worker, n, % (95% CI)
102
8·8 (7·3–11)
26
6·3 (4·2–9·5)
31
5·6 (3·8–8·2)
33
19 (13–26)
11
39 (22–61)
2
37 (8·9–78)
Other
§
, n, % (95% CI)
66
5·7 (4·5–7·2)
14
3·5 (2.0–6·2)
37
6·8 (4·8–9·5)
13
7·2 (3·9–13)
1
5 (0·7–27)
1
0·2 (0–100)
At least one underlying condition, n, %
(95% CI)
243
21 (19–24)
79
20 (16–24)
113
21 (17–25)
43
24 (18–32)
8
31 (15–53)
0
..
Hospitalised, n, % (95% CI)
¥
82
7·1 (5·8–8·7)
29
7·2 (4·9–11)
33
6.0 (4·1–8·7)
15
8·3 (4·7–14)
5
19 (7·3–42)
0
..
ICU admission, n, % (95% CI)
¥
9
0·8 (0·4–1·5)
3
0·8 (0·2–2·6)
5
0·8 (0·3–2·3)
0
0 (0–100)
1
3·6 (0–100)
0
..
Death, n, % (95% CI)
¥
17
1·5 (0·9–2·4)
2
0·1 (0–100)
6
1·1 (0·4–2·7)
9
4·9 (2·4–10)
1
0 (0–100)
0
..
PRESENTATION PERIODS
¶
Confirmed case, n, % (95% CI)
1153
77 (74–79)
111
85 (77–90)
588
85 (83–88)
402
68 (64–71)
40
53 (41–65)
12
80 (52–96)
Basis for case detection, Total (%)
1153
100
111
100
588
100
402
100
40
100
12
100
Contact tracing, n, % (95% CI)
450
39 (36–42)
27
24 (17–33)
171
29 (25–33)
214
53 (48–58)
30
75 (59–87)
8
67 (35–90)
Border, n, % (95% CI)
39
3·4 (2·4–4·6)
3
2·7 (0·6–7·7)
24
4·1 (2·6–6·0)
8
2·0 (0·9–3·9)
3
7·5 (1·6–20)
1
8·3 (0·2–38)
Healthcare presentation, n, % (95% CI)
659
57 (54–60)
81
73 (64–81)
391
66 (63–70)
177
44 (39–49)
7
18 (7·3–33)
3
25 (5·5–57)
Other
‖
, n, % (95% CI)
5
0·4 (0·1–1·0)
0
..
2
0·3 (0–1·2)
3
0·7 (0·2–2·2)
0
..
0
..
3
* Cases were assigned to study exposure periods by sampling incubation periods from a Weibull distribution
15
prior to illness onset (or prior to notification date if no onset
data). Mean case numbers, rates, proportions and confidence intervals are pooled estimates from 1000 replicate incubation samplings, thus capturing uncertainty in incubation
period.
† Excludes imported cases.
§ Includes airline crew, other frontline service workers e.g. police.
¥ Outcomes are not mutually exclusive, i.e. cases could be assigned to more than one of hospitalisation, Intensive Care Unit (ICU) admission, and death. COVID-19 was
reported as the primary cause of death on the COVID-19 case report form for all deceased cases.
¶ Each case was assigned to a study presentation period by date of illness onset (or notification date if no symptom data).
‖ Includes asymptomatic self-referral for testing outside of case definition or contact tracing protocol.
95 % CI = 95 percent confidence intervals.
4
Supplementary Table 2: Characteristics of COVID-19 cases associated with severe disease outcomes
Characteristic
Non-
severe
outcome
(%)
Severe
outcome
¥
(%)
Total cases
in stratum
Crude
β
or age-sex
adjusted analysis
OR (95% CI)
Multivariable
analysis
‡
OR (95% CI)
Total
1387
108
1495
Age group (years)
<1
4
(0·3)
0
(0)
4
..
..
1–4
16
(1·2)
2
(1·9)
18
3·83 (0·81–18·07)
3·13 (0·64–15·23)
5–19
132
(10)
2
(1·9)
134
0·46 (0·11–2·04)
0·42 (0·09–1·89)
20–34
490
(35)
16
(15)
506
Ref
Ref
35–49
285
(21)
13
(12)
298
1·4 (0·66–2·95)
1·2 (0·55–2·63)
50–64
311
(22)
29
(27)
340
2·86 (1·53–5·34)
2·72 (1·40–5·30)
65–79
128
(9·2)
28
(26)
156
6·70 (3·52–12·76)
5·42 (2·54–11·57)
≥80 years
21
(1·5)
18
(17)
39
26·25 (11·76–58·58)
8·25 (2·59–26·31)
Sex
Female
773
(56)
58
(54)
831
Ref
Ref
Male
614
(44)
50
(46)
664
1·09 (0·73, 1·61)
0·86 (0·55–1·35)
Ethnicity
European or Other
1012
(73)
75
(69)
1087
Ref
Ref
Māori
122
(8·8)
10
(9·3)
132
1·36 (0·65–2·85)
1·28 (0·57–2·89)
Pacific peoples
70
(5·0)
9
(8·3)
79
3·07 (1·38–6·85)
2·76 (1·14–6·68)
Asian
167
(12)
14
(13)
181
2·08 (1·1–3·95)
2·15 (1·10–4·20)
Unknown
16
(1·2)
0
(0)
16
-
-
NZDep quintile
1
326
(24)
16
(15)
342
Ref
Ref
2
331
(24)
28
(26)
359
1·79 (0·93–3·44)
1·72 (0·89–3·33)
3
247
(18)
12
(11)
259
0·98 (0·44–2·15)
0·81 (0·36–1·82)
4
254
(18)
24
(22)
278
1·77 (0·89–3·51)
1·35 (0·66–2·73)
5
149
(11)
20
(19)
169
2·36 (1·13–4·95)
1·43 (0·65–3·16)
High-risk occupation
or Aged Residential
Care residency
High-risk worker
±
158
(11)
11
(10)
169
1·31 (0·66–2·61)
..
Healthcare worker
±
139
(10)
9
(8·3)
148
1·22 (0·58–2·57)
..
Aged Residential Care
resident
24
(1·7)
23
(21)
47
3·86 (1·59–9·35)
..
Rural dweller
Rural resident
223
(16)
14
(13)
237
0·86 (0·47–1·59)
..
Source of infection
Imported
542
(39)
30
(28)
572
Ref
..
Import-related
432
(31)
24
(22)
456
0·92 (0·51–1·64)
..
Locally-acquired
413
(30)
54
(50)
467
2·32 (1·40–3·82)
..
Exposure Phase
†
2 Feb to 15 Mar
437
(32)
32
(29)
469
Ref
..
16 Mar to 25 Mar
628
(45)
39
(36)
667
0·84 (0·48–1·48)
..
26 Mar to 10 Apr
276
(20)
28
(26)
304
1·38 (0·77–2·48)
..
11 Apr to 27 Apr
38
(2·7)
9
(8·3)
47
3·08 (1·22–7·77)
..
5
28 Apr to 13 May
7
(0·5)
1
(0.9)
8
..
..
Underlying condition
€
At least one reported
underlying condition
251
(18)
43
(40)
294
1·81 (1·16–2·83)
..
Cardiovascular disease
(including
hypertension)
92
(6·6)
20
(19)
112
1·28 (0·71–2·31)
..
Diabetes
46
(3·3)
11
(10)
57
1·73 (0·82–3·64)
..
Chronic lung condition
118
(8·5)
11
(10)
129
1·12 (0·56–2·23)
..
Malignancy
11
(0·8)
2
(1·9)
13
2·36 (0·52–10·79)
..
Immunodeficiency,
including HIV
5
(0·4)
0
(0)
5
..
..
Liver Disease
4
(0·3)
1
(0·9)
5
..
..
Chronic neurological
or neuromuscular
disease
5
(0·4)
8
(7·4)
13
..
..
Renal failure
3
(0·2)
4
(3·7)
7
..
..
Pregnant
13
(0·9)
3
(2·8)
16
..
..
Post-partum
0
(0)
0
(0)
0
..
..
¥
Hospitalisation and/or death. COVID-19 was reported as the primary cause of death on the COVID-19 case
report form for all deceased cases.
ß
Crude odds ratios are presented for age, sex, source of infection and exposure phase variables only. Due to
significant confounding by age, all other odds ratios are presented with adjustment for age and sex.
‡
Multivariable adjustment for age, sex, ethnicity, Aged Residential Care facility residency, socio-economic
status and having at least one underlying condition.
±
High-risk workers who were imported cases (i.e. infection not acquired while working in New Zealand) were
excluded from this analysis. Healthcare worker is a subset of the high-risk worker group.
†
Cases were assigned to study exposure periods by sampling incubation periods from a Weibull distribution
15
prior to illness onset (or prior to notification date if asymptomatic or onset unknown). Mean case numbers,
proportions, odds ratios and confidence intervals are pooled estimates from 1000 replicate incubation samplings,
thus capturing uncertainty in incubation period.
€
There was insufficient data for precise estimates of risk associated with individual underlying conditions and
analyses were not performed for conditions with <20 total observations.
Complete observations were available for 1495 cases.
95% CI = 95 percent confidence intervals.
6
Supplementary Table 3: Incidence rates of testing per 100,000 person-days at risk in New Zealand over
the study period and by response phase, stratified by population characteristics: sex, ethnicity, age group,
NZDep quintile and District Health Board residence
Characteristic
Phase 1 incidence
rate (95% CI)
Phase 2 incidence
rate (95% CI)
Phase 3 incidence
rate (95% CI)
Phase 4 incidence
rate (95% CI)
Phase 5 incidence
rate (95% CI)
Sex
Female
0·5 (0·5-0·6)
30·6 (29·9-31·2)
66·7 (65·9-67·5)
90·6 (89·7-91·5)
129·6 (128·5-130·8)
Male
0·5 (0·4-0·5)
23·9 (23·3-24·6)
46·2 (45·6-46·9)
65·4 (64·7-66·2)
89·3 (88·3-90·2)
Ethnicity
Asian
1·0 (0·9-1·1)
20·9 (19·9-21·9)
39·3 (38·2-40·4)
43·0 (41·9-44·1)
77·0 (75·4-78·5)
European or Other
0·4 (0·4-0·5)
29·4 (28·8-30·0)
59·8 (59·2-60·5)
82·8 (82·0-83·6)
110·7 (109·8-111·7)
Māori
0·2 (0·2-0·3)
20·2 (19·3-21·3)
52·9 (51·7-54·2)
80·8 (79·3-82·3)
117·3 (115·4-119·2)
Pacific
0·5 (0·3-0·6)
30·4 (28·6-32·4)
67·7 (65·4-70·0)
107·6 (104·8-110·4)
154·0 (150·6-157·4)
Age group
1 year
0·3 (0·1-0·5)
2·9 (1·7-4·6)
6·2 (4·7-7·9)
8·6 (6·9-10·5)
9·8 (8·0-12·0)
1 to 4 years
0·5 (0·4-0·6)
16·4 (14·8-18·0)
26·5 (24·9-28·2)
34·3 (32·5-36·1)
35·3 (33·5-37·2)
5 to 19 years
0·2 (0·2-0·3)
12·5 (11·8-13·3)
21·6 (20·9-22·4)
29·2 (28·4-30·1)
41·5 (40·5-42·6)
20 to 34 years
0·7 (0·6-0·7)
39·7 (38·6-40·9)
64·9 (63·7-66·1)
74·4 (73·1-75·6)
116·9 (115·3-118·5)
35 to 49 years
0·7 (0·6-0·7)
36·4 (35·2-37·7)
77·2 (75·7-78·6)
99·8 (98·2-101·4)
140·2 (138·3-142·1)
50 to 64 years
0·5 (0·5-0·6)
31·4 (30·3-32·6)
76·6 (75·1-78·0)
112·0 (110·3-113·6)
161·6 (159·5-163·7)
65 to 79 years
0·5 (0·4-0·6)
19·4 (18·3-20·6)
55·3 (53·9-56·9)
96·2 (94·3-98·2)
122·1 (119·9-124·3)
≥80 years
0·5 (0·3-0·7)
12·6 (11·0-14·3)
51·4 (48·8-54·1)
108·0 (104·3-111·7)
114·2 (110·4-118·2)
NZDep quintile
1
0·5 (0·5-0·6)
30·7 (29·7-31·8)
52·4 (51·3-53·5)
66·5 (65·3-67·8)
92·6 (91·1-94·1)
2
0·5 (0·5-0·6)
27·3 (26·3-28·3)
50·8 (49·7-51·9)
65·8 (64·6-67·0)
95·1 (93·6-96·6)
3
0·5 (0·4-0·6)
25·0 (24·1-26·0)
53·8 (52·6-54·9)
70·7 (69·4-72·0)
100·7 (99·2-102·3)
4
0·4 (0·4-0·5)
23·6 (22·7-24·6)
55·7 (54·5-56·9)
78·5 (77·1-79·8)
113·9 (112·3-115·6)
5
0·4 (0·3-0·4)
22·9 (21·9-23·8)
58·3 (57·1-59·5)
93·7 (92·3-95·2)
125·1 (123·3-126·9)
District Health Board
Auckland
1·3 (1·2-1·5)
42·2 (40·5-44·0)
56·0 (54·5-57·6)
64·0 (62·3-65·6)
109·8 (107·6-112·0)
Bay of Plenty
0·1 (0·0-0·2)
14·8 (13·3-16·4)
48·7 (46·5-50·9)
90·4 (87·5-93·3)
77·7 (75·0-80·6)
Canterbury
0·3 (0·3-0·4)
16·5 (15·5-17·6)
42·5 (41·2-43·9)
69·8 (68·2-71·5)
87·5 (85·6-89·4)
Capital and Coast
0·3 (0·2-0·4)
34·1 (32·1-36·2)
60·0 (57·9-62·2)
75·8 (73·5-78·1)
92·0 (89·4-94·6)
Counties Manukau
0·6 (0·5-0·7)
30·8 (29·4-32·3)
62·0 (60·4-63·7)
86·5 (84·7-88·4)
127·6 (125·3-129·9)
Hawke's Bay
0·2 (0·1-0·4)
19·6 (17·5-21·8)
59·0 (56·1-62·0)
82·5 (79·1-85·9)
98·5 (94·8-102·4)
Hutt Valley
0·2 (0·1-0·4)
22·2 (19·9-24·7)
58·3 (55·2-61·4)
83·6 (80·1-87·2)
87·9 (84·1-91·7)
Lakes
0·2 (0·1-0·3)
15·5 (13·2-18·0)
58·7 (55·1-62·3)
74·6 (70·8-78·6)
93·3 (88·8-97·9)
MidCentral
0·2 (0·1-0·3)
12·8 (11·3-14·6)
38·0 (35·8-40·3)
76·6 (73·5-79·7)
80·6 (77·4-84·0)
Nelson Marlborough
0·4 (0·2-0·5)
23·3 (20·9-25·9)
39·0 (36·6-41·6)
63·8 (60·7-66·9)
107·9 (103·8-112·2)
Northland
0·3 (0·2-0·4)
31·2 (28·7-33·9)
56·9 (54·2-59·7)
69·4 (66·5-72·4)
136·0 (131·8-140·3)
South Canterbury
0·2 (0·0-0·4)
16·9 (13·8-20·6)
47·2 (43·0-51·8)
92·9 (87·0-99·0)
105·8 (99·4-112·5)
Southern
0·3 (0·3-0·5)
22·4 (20·8-24·1)
67·1 (64·9-69·3)
80·7 (78·4-83·1)
108·1 (105·3-110·9)
Tairawhiti
0·1 (0·0-0·4)
17·4 (13·9-21·5)
39·8 (35·5-44·4)
196·4 (187·0-206·2)
134·6 (126·6-143·0)
Taranaki
0·1 (0·0-0·3)
17·8 (15·5-20·3)
36·0 (33·4-38·8)
75·7 (72·0-79·5)
137·3 (132·1-142·7)
Waikato
0·2 (0·1-0·2)
31·0 (29·4-32·8)
76·3 (74·3-78·4)
86·0 (83·9-88·2)
129·4 (126·7-132·1)
Wairarapa
0·3 (0·1-0·6)
52·5 (46·1-59·5)
84·7 (78·2-91·7)
67·6 (62·0-73·7)
76·4 (70·2-83·0)
Waitemata
0·9 (0·8-1·0)
31·6 (30·2-33·0)
58·0 (56·5-59·5)
72·2 (70·6-73·8)
121·1 (119·0-123·3)
7
West Coast
0·1 (0·0-0·4)
12·6 (9·1-17·1)
62·6 (56·0-69·8)
68·2 (61·5-75·5)
75·4 (68·1-83·3)
Whanganui
0·1 (0·0-0·4)
7·6 (5·7-10·1)
31·8 (28·5-35·4)
98·2 (92·4-104·2)
190·4 (182·1-199·1)
Incidence rates and 95 percent confidence intervals (95% CI) presented as tests per 100,000 person-days at risk.
8
Supplementary Table 4: Distributions, Maximum Likelihood Estimates with bootstrapped 95%
uncertainty intervals for key time-to-event measures for COVID-19 cases in New Zealand by response
phase
*
a) illness onset to notification date intervals in days (confirmed and probable cases)
‡
Onset to report date
Distribution
Shape
Rate
Mean
5% Quantile
50%
Quantile
95%
Quantile
Overall
Gamma
1·1
0·2
6·7
0·5
4·9
19·3
95% CI
(1·1, 1·2)
(0·2, 0·2)
(6·4, 7·1)
(0·4, 0·5)
(4·6, 5·1)
(18·3, 20·4)
Phase 1
3·1
0·3
10·8
3·0
9·7
22·5
95% CI
(2·5, 3·9)
(0·2, 0·4)
(9·8, 11·9)
(2·4, 3·7)
(8·8, 10·7)
(19·9, 25·0)
Phase 2
1·7
0·2
7·7
1·1
6·3
19·2
95% CI
(1·6, 1·9)
(0·2, 0·2)
(7·2, 8·1)
(0·9, 1·3)
(5·9, 6·7)
(17·9, 20·4)
Phase 3
0·9
0·2
5·2
0·2
3·4
16·2
95% CI
(0·8, 1.0)
(0·2, 0·2)
(4·8, 5·7)
(0·1, 0·3)
(3·1, 3·8)
(14·7, 17·8)
Phase 4
0·8
0·3
2·7
0·1
1·7
9·0
95% CI
(0·6, 1·0)
(0·2, 0·4)
(2·1, 3·6)
(0·0, 0·2)
(1·2, 2·2)
(6·6, 12·0)
b) illness onset to isolation date intervals in days (confirmed and probable cases)
§
Time period
Distribution
Mean
SD
5% Quantile
50%
Quantile
95%
Quantile
Overall
Normal
1·2
6·5
-9·6
11·9
95% CI
(0·8, 1·5)
(6·3, 6·8)
(-10·1, -9·0)
(11·4, 12·4)
Phase 1
7·2
5·5
-1·7
16·3
95% CI
(6·3, 8·2)
(4·8, 6·1)
(-3·2, -0·2)
(14·9, 17·6)
Phase 2
2·4
5·4
-6·6
11·3
95% CI
(1·9, 2·8)
(5·2, 5·7)
(-7·2, -6.0)
(10·7, 11·9)
Phase 3
-1·1
6·1
-11·2
9·0
95% CI
(-1·6, -0·6)
(5·8, 6·5)
(-11·9, -10·4)
(8·3, 9·8)
Phase 4
-2·7
8·3
-16·4
11·0
95% CI
(-4·7, -0·8)
(7·0, 9·7)
(-19·5, -13·4)
(7·9, 13·9)
c) illness onset to case confirmation intervals in days
†¶
Onset to diagnosis
Distribution
Shape
Rate
Mean
5% Quantile
50%
Quantile
95%
Quantile
Overall
Gamma
1·8
0·3
7·1
1·1
5·8
17·4
95% CI
(1·6, 1·9)
(0·2, 0·3)
(6·8, 7·4)
(1·0, 1·2)
(5·5, 6·1)
(16·5, 18·3)
Phase 1
4·3
0·4
10·6
3·8
9·8
20·2
95% CI
(3·3, 5·7)
(0·3, 0·5)
(9·7, 11·6)
(3·1, 4·6)
(8·9, 10·7)
(18·1, 22·5)
Phase 2
2·3
0·3
7·5
1·5
6·4
17·1
95% CI
(2·0, 2·6)
(0·3, 0·3)
(7·1, 7·9)
(1·4, 1·8)
(6·0, 6·8)
(16·0, 18·1)
Phase 3
1·5
0·3
5·9
0·7
4·7
15·3
95% CI
(1·4, 1·8)
(0·2, 0·3)
(5·5, 6·5)
(0·6, 0·9)
(4·3, 5·1)
(13·9, 16·8)
Phase 4
1·4
0·6
2·6
0·3
2·0
6·8
95% CI
(1·0, 2·3)
(0·3, 1·0)
(1·9, 3·4)
(0·1, 0·6)
(1·5, 2·8)
(4·9, 9·2)
*Observations were too small for Phase 5 calculations.
‡
Observations available for 1468 cases.
§
Observations available for 1463 cases.
9
¶
Observations available for 1115 cases.
†
Sensitivity analysis using onset to confirmation interval (i.e. excluding probable cases) found no significant
differences in timeliness except the average onset to notification interval was shorter in Phase 3, which had the
highest proportion of probable cases.
95% CI = 95 percent uncertainty intervals.
Negative values represent days prior to illness onset.
10
Supplementary Figure 1: Individual symptoms and selected symptom combinations among COVID-19
cases in New Zealand
Data were available for 1472 of 1478 symptomatic cases. Proportions are presented with 95 percent confidence
intervals.
11
Supplementary Figure 2: Further features of the New Zealand COVID-19 response timeline
A. Daily international passenger arrivals at national Ports of Entry and Government Response
Stringency Index for New Zealand
B. Daily percentage change in national population mobility from baseline prior to the first national
movement restrictions
Supplementary figure 2B dashed-line represents last day of baseline period of national population
mobility prior to first national movement restriction on 16 March.
12
Supplementary Figure 3: Key time-to-event intervals by response phase
A. COVID-19 case illness onset to notification date intervals
B.
COVID-19 case onset to isolation date intervals
Distribution parameters were calculated using maximum likelihood estimation. Uncertainty in the parameters
were estimated by bootstrapping. Phase 5 was excluded from analyses due to the small numbers. Further detail is
provided in supplementary table 4. Complete onset to notification observations were available for 1468 cases, and
1463 cases for onset to isolation analysis. 95% UI = 95 percent uncertainty intervals. Negative values represent
days prior to illness onset.