Table 2:

SARS-CoV-2 seroprevalence by serosurvey and category (any or infection-induced), by age group

Age group, yrSeroprevalence categorySeropositivity estimate*, % (95% CrI)
Serosurvey 1 March 2020Serosurvey 2 May 2020Serosurvey 3 Sept. 2020Serosurvey 4 Jan. 2021Serosurvey 5 May–June 2021Serosurvey 6 Sept.–Oct. 2021Serosurvey 7 March 2022Serosurvey 8 July–Aug. 2022
0–4Any6.1 (3.9–9.0)18.7 (13.3–25.0)17.6 (12.5–23.5)71.9 (64.8–78.4)84.5 (77.6–89.8)
Infection-induced§0.3 (0.05–0.9)0.6 (0.1–1.4)1.0 (0.5–1.7)5.9 (3.6–8.8)13.4 (9.9–17.5)13.3 (9.8–17.4)62.9 (55.8–69.5)72.6 (65.6–79.2)
5–9Any5.7 (3.7–8.6)18.4 (13.6–24.1)14.8 (10.4–20.2)89.9 (85.5–93.5)92.8 (89.3–95.5)
Infection-induced§0.3 (0.04–1.0)0.5 (0.1–1.3)1.0 (0.5–1.6)5.5 (3.5–8.4)13.7 (10.1–17.8)11.3 (8.1–15.0)65.9 (59.3–72.2)70.5 (64.6–76.3)
10–19Any3.1 (1.6–4.8)21.7 (16.4–27.5)83.8 (78.6–88.4)96.1 (93.6–98.2)96.5 (93.9–98.4)
Infection-induced§0.3 (0.05–0.9)0.6 (0.2–1.5)1.1 (0.6–1.8)2.7 (1.4–4.4)11.8 (8.6–15.6)11.3 (8.1–15.0)56.0 (49.5–62.4)76.0 (70.5–81.4)
20–29Any4.9 (3.0–7.5)44.2 (37.7–50.8)87.7 (82.8–91.9)97.2 (95.0–98.7)98.8 (97.2–99.7)
Infection-induced§0.3 (0.1–0.9)0.5 (0.1–1.2)1.0 (0.6–1.8)4.3 (2.5–6.7)11.9 (8.6–15.5)8.9 (6.1–12.2)49.7 (43.0–56.6)69.5 (63.3–75.4)
30–39Any3.7 (2.1–5.6)54.8 (48.2–61.6)88.6 (84.1–92.4)97.5 (95.4–98.9)98.1 (95.7–99.4)
Infection-induced§0.3 (0.05–0.9)0.6 (0.2–1.3)1.1 (0.6–2.1)3.1 (1.6–4.9)9.5 (6.6–12.9)10.5 (7.4–14.2)54.4 (48.2–60.8)64.6 (57.6–71.2)
40–49Any4.4 (2.7–6.6)68.0 (61.8–73.8)91.3 (87.3–94.5)96.8 (94.4–98.5)97.8 (95.5–99.1)
Infection-induced0.4 (0.1–1.1)0.5 (0.1–1.2)0.9 (0.4–1.5)3.7 (2.2–5.8)9.7 (6.9–12.9)10.1 (7.1–13.7)44.5 (38.1–51.3)64.1 (57.6–70.5)
50–59Any3.3 (1.8–5.2)73.1 (67.1–78.7)91.7 (87.6–94.9)96.3 (93.8–98.2)97.9 (95.7–99.2)
Infection-induced§0.4 (0.1–1.1)0.6 (0.2–1.7)1.0 (0.6–1.8)2.8 (1.4–4.6)7.6 (4.8–10.7)9.2 (6.4–12.5)32.7 (26.7–39.0)59.6 (53.0–66.3)
60–69Any3.3 (1.7–5.2)80.1 (74.3–85.4)89.6 (85.3–93.3)97.1 (94.8–98.7)98.0 (96.1–99.3)
Infection-induced§0.3 (0.04–0.9)0.5 (0.1–1.2)1.0 (0.5–1.6)2.8 (1.4–4.6)8.7 (5.9–11.9)5.8 (3.4–8.7)24.9 (19.6–30.6)42.3 (36.0–48.6)
70–79Any3.5 (1.9–5.4)79.4 (73.5–84.7)92.9 (89.2–95.8)95.7 (93.0–97.8)97.4 (95.2–98.9)
Infection-induced§0.3 (0.05–0.9)0.5 (0.1–1.2)1.0 (0.5–1.6)3.1 (1.7–4.8)10.2 (7.3–13.5)8.2 (5.50–11.3)14.3 (9.8–19.3)43.1 (36.6–49.7)
≥ 80Any5.0 (3.1–7.7)71.9 (65.6–77.8)92.7 (88.9–95.8)93.4 (89.6–96.3)98.2 (96.5–99.4)
Infection-induced§0.3 (0.1–0.9)0.5 (0.1–1.2)0.9 (0.4–1.5)3.7 (2.1–5.9)7.6 (4.8–10.7)5.6 (3.2–8.6)15.4 (11.1–20.4)37.9 (31.7–44.3)
All agesAny4.0 (3.2–5.0)56.2 (54.1–58.4)82.7 (81.1–84.2)95.2 (94.3–96.0)97.0 (96.2–97.8)
Infection-induced§0.3 (0.1–0.8)0.6 (0.2–1.1)1.0 (0.6–1.5)3.5 (2.7–4.4)10.1 (8.8–11.6)9.4 (8.1–10.8)42.5 (40.2–44.9)61.1 (58.8–63.4)
  • Note: CrI = credible interval, NP = nucleocapsid protein, S1 = spike 1 protein.

  • * Adjusted for age, sex and health authority of residence or if not available (< 0.5% overall), then of ordering physician.

  • Seropositivity defined by signal above the cut-off threshold on at least 2 chemiluminescent immunoassays.

  • Any seropositivity includes seropositivity induced by vaccine, infection or both. Any seropositivity required dual-assay positivity, including anti-S1 or anti-NP antibody detection. Spike target may be the S1 or S1 receptor-binding domain.

  • § For serosurveys 1–3 in 2020, all dual-assay seropositivity was considered to be from infection, regardless of assay type. Thereafter, for serosurveys 4–8, infection-induced seroprevalence estimates required dual-assay positivity that included both anti-NP and anti-S1 antibody detection. Spike target may be the S1 or S1 receptor-binding domain. Those with evidence of infection-induced antibody (anti-NP detection) may or may not have been vaccinated.