Factors that determine the presence or absence of SARS-CoV-2 infection by close contact_
| Odds ratio | 95% confidence interval Lower-Upper | P | |
|---|---|---|---|
| Age | 1.00 | 0.997–1.010 | 0.227 |
| Underlying disease | 1.19 | 0.853–1.660 | 0.306 |
| Female | 2.23 | 1.700–2.930 | <0.0001 |
Characteristics of the cases of SARS-CoV-2 infection in Fukui Prefecture, Japan_
| Period 1* (n = 122) | Period 2† (n = 122) | Period 3‡ (n = 301) | P | |
|---|---|---|---|---|
| Age (years;IQR) | 54 (45.3–66) | 59 (42–77) | 48 (28–66) | <0.0001§ |
| 0–10 | 2 (1.6) | 1 (0.8) | 12 (4) | 0.178 |
| 11–20 | 3 (2.5) | 6 (4.9) | 24 (8) | 0.081 |
| 21–30 | 7 (5.7) | 12 (4.9) | 55 (18.3) | 0.001|| |
| 31–40 | 14 (11.5) | 10 (8.2) | 38 (12.6) | 0.444 |
| 41–50 | 18 (14.8) | 12 (9.8) | 39 (13.0) | 0.536 |
| 51–60 | 36 (29.5) | 10 (8.2) | 43 (14.3) | <0.0001** |
| >61 | 42 (34.4) | 71 (58.2) | 90 (29.9) | <0.0001†† |
| Sex, n (%) | ||||
| Male | 74 (60.7) | 65 (53.3) | 145 (48.2) | – |
| Female | 48 (29.3) | 57 (46.7) | 156 (51.8) | – |
| Presence of underlying disease | 59 (48.4) | 53 (43.4) | 96 (31.9) | 0.005‡‡ |
| Unknown underlying disease | 0 (0) | 0 (0) | 17 (5.6) | – |
Characteristics of definitions of close contacts and infection and attack rates in four Asian countries_
| Time | Distance | Protective measure* | Observation period | Secondary infection rate | Secondary attack rate | ||
|---|---|---|---|---|---|---|---|
| <2.0 m | <1.0 m | ||||||
| Taiwan | 15 min or more (conversing) | ○ (medical institution) | None (medical institution) | Jan – Apr 2020 | 0.8% | 0.7% | |
| Singapore | 30 min (with patient) | ○ | - | Jan – Apr 2020 | - | 2.4% | |
| Guangzhou, China | ○ | None (social life) | Jan – Mar 2020 | 3.7% | 3.5% | ||
| Guangzhou, China | ○ | None (social life) | Before March 2020 | - | 4.4% | ||
| Hubei Province, China | ○ | None (social life) | Jan – Feb 2020 | - | 6.5% | ||
| Nagano, Japan | 15 min or more (contact) | ○ | None (social life) | Aug – Sep 2020 | - | 15.0% | |
| Our study | Had prolonged contact | ○ | None (social life) | Mar – Jun 2020 | Period 1:13.3% | - | |
| Fukui, Japan | 15 minutes or more (contact) | ○ | None (social life) | Jul – Sep 2020 | Period 2:19.2% | - | |
Odds ratios of having a positive SARs-CoV-2 test result among close contacts of patients with COVID-19_
| Period | Close contact with COVID-19 patient | SARS-CoV-2 test | Stratified independence test (Pearson's χ2 test) | Stratified odds ratio | ||
|---|---|---|---|---|---|---|
| Positive | Negative | Odds ratio | 95% confidence interval Lower-Upper | |||
| 1* | No, n (%) | 65 (2.2) | 2866 | P < 0.0001 | 6.76 | 4.66–9.80 |
| Yes, n (%) | 57 (13.3) | 372 | ||||
| 2† | No, n (%) | 66 (1.1) | 6011 | P < 0.0001 | 21.70 | 14.85–31.71 |
| Yes, n (%) | 56 (19.2) | 235 | ||||
| 3‡ | No, n (%) | 147 (0.7) | 21596 | P < 0.0001 | 36.90 | 29.04–46.91 |
| Yes, n (%) | 154 (20.0) | 613 | ||||
Number of close contacts and SARS-CoV-2 positivity rate among close contacts patients with COVID-19 in Fukui Prefecture, Japan_
| Period 1* | Period 2† | Period 3‡ | P | |
|---|---|---|---|---|
| Number of close contacts | 429 | 291 | 767 | – |
| Positivity rate among close contacts, n (%) | 57 (13.3) | 56 (19.2) | 154 (20.0) | 0.009 |