Volume 29, Number 5—May 2023
Research
Case–Control Study of Long COVID, Sapporo, Japan
Toshiaki Asakura1, Takashi Kimura1
, Isaku Kurotori, Katabami Kenichi, Miyuki Hori, Mariko Hosogawa, Masayuki Saijo, Kaori Nakanishi, Hiroyasu Iso, and Akiko Tamakoshi
, Isaku Kurotori, Katabami Kenichi, Miyuki Hori, Mariko Hosogawa, Masayuki Saijo, Kaori Nakanishi, Hiroyasu Iso, and Akiko Tamakoshi
Table 1
Demographic of participants in a case–control study of long COVID, Sapporo, Japan*
| Characteristics | No. (%) |
|
|---|---|---|
| Cases, n = 3,694 | Controls, n = 3,672 | |
| Age group, y | ||
| 20–29 | 608 (16.5) | 420 (11.4) |
| 30–39 | 772 (20.9) | 735 (20.0) |
| 40–49 | 1,011 (27.4) | 1,001 (27.3) |
| 50–65 |
1,303 (35.3) |
1,516 (41.3) |
| Sex | ||
| M | 1,528 (41.4) | 1,591 (43.3) |
| F |
2,166 (58.6) |
2,081 (56.7) |
| No. COVID-19 vaccines† | ||
| 0 | 407 (11.0) | 220 (6.0) |
| 1 | 65 (1.8) | 22 (0.6) |
| 2 | 2,233 (60.4) | 1,982 (54.0) |
| 3 |
989 (26.8) |
1,448 (39.4) |
| Time after illness onset, mo | ||
| 2–3‡ | 55 (1.5) | NA |
| 4–6 | 126 (3.4) | NA |
| 7–9 | 1,117 (30.2) | NA |
| 10–12 | 1,264 (34.2) | NA |
| 13–18 | 451 (12.2) | NA |
| >19 |
681 (18.4) |
NA |
| Illness severity‡ | ||
| Asymptomatic | 115 (3.1) | NA |
| Mild | 2,952 (79.9) | NA |
| Moderate | 334 (9.0) | NA |
| Severe | 36 (1.0) | NA |
| Missing | 257 (7.0) | NA |
*NA, not applicable. †As of April 5, 2022. ‡Severity during acute phase of infection.
1These authors contributed equally to this article.
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Page updated: April 18, 2023
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