Seropositivity and risk factors for SARS-CoV-2 infection in a South Asian community in Ontario: a cross-sectional analysis of a prospective cohort study

Sonia S. Anand; Corey Arnold; Shrikant I. Bangdiwala; Shelly Bolotin; Dawn Bowdish; Rahul Chanchlani; Russell J. de Souza; Dipika Desai; Sujane Kandasamy; Farah Khan; Zainab Khan; Marc-André Langlois; Jayneel Limbachia; Scott A. Lear; Mark Loeb; Lawrence Loh; Baanu Manoharan; Kiran Nakka; Martin Pelchat; Zubin Punthakee; Karleen M. Schulze; Natalie Williams; Gita Wahi

doi:10.9778/cmajo.20220031

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Figure 1:
Daily rates of SARS-CoV-2 infection in Ontario and the Peel Region, Mar. 14, 2020, to Oct. 31, 2021. Data from Public Health Ontario: COVID-19 pandemic comparing Peel Region with Ontario. (10)
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Figure 2:
Cumulative incidence of cases of SARS-CoV-2 infection (per 100 000) as of Oct. 3, 2021, by seroprevalence by geographic region (forward sortation area). Cumulative incidence data from ICES. (18) Seroprevalence data from the COVID CommUNITY study.
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Figure 3:
Top-ranked sources of COVID-19 health information according to respondents (n = 585 respondents).

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Table 1:

Demographic characteristics of participants in the COVID CommUNITY study in Ontario

Characteristic	No. (%) of participants n = 916
Sex, n = 916
Female	451 (49.2)
Male	462 (50.4)
Self-described	3 (0.3)
Age group, yr, n = 906
18–24	95 (10.5)
25–34	233 (25.7)
35–44	247 (27.3)
45–54	157 (17.3)
55–64	94 (10.4)
≥ 65	80 (8.8)
Vaccinated, n = 916
Yes, 2 doses	65 (7.1)
Yes, 1 dose	393 (42.9)
No	458 (50.0)
Self-reported history of previous SARS-CoV-2 infection, n = 699
Yes	88 (12.6)
No	600 (85.8)
Unknown	11 (1.6)
Median household income (2015) based on FSA, $, n = 904
40 000–59 999	9 (1.0)
60 000–79 999	97 (10.7)
80 000–99 999	570 (63.1)
≥ 100 000	228 (25.2)
Essential worker,^* n = 693
Yes	228 (32.9)
No	352 (50.8)
Prefer not to answer	113 (16.3)
Currently employed, n = 693
Yes	435 (62.8)
No	169 (24.4)
Prefer not to answer	89 (12.8)
Completed education, n = 693
High school or less	121 (17.5)
College, trade, certificate	89 (12.8)
University degree	453 (65.4)
Prefer not to answer	30 (4.3)
Multigenerational household, n = 654
Yes	125 (19.1)
No	451 (69.0)
Prefer not to answer	78 (11.9)
Time in Canada, yr, n = 717
≤ 10	223 (31.1)
> 10	384 (53.6)
Born in Canada	85 (11.9)
Prefer not to answer	25 (3.5)
Mother tongue,^† n = 732
Punjabi or Urdu	363 (49.6)
Hindi	83 (11.3)
Gujarati	106 (14.5)
Other South Asian languages	152 (20.8)
English	54 (7.4)
Prefer not to answer	4 (0.5)
Medical history, n = 679
Cardiovascular disease (MI, angioplasty or stroke)	21 (3.1)
Chronic medical condition requiring medication, n = 666
Hypertension	48 (7.2)
Diabetes	53 (8.0)
Arthritis	10 (1.5)
Chronic lung disease	1 (0.2)
Cancer	1 (0.2)
Smoking status, n = 641
Never	555 (86.6)
Former	53 (8.3)
Current	33 (5.1)
Location, n = 905
Region of Peel	830 (91.7)
City of Brampton	742 (82.0)
Town of Caledon	39 (4.3)
City of Mississauga	49 (5.4)

Note: FSA = forward sortation area, MI = myocardial infarction.
↵* Examples of essential work: food processing, manufacturing or distribution; transportation; health care; education; utilities.
↵† Multiple answers can be selected.

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Table 2:

Seroprevalence by demographic characteristics

Characteristic	No. of samples tested	No. of positives	Seropositive, % (95% CI)^*
Overall	916	212	22.9 (20.1–26.1)
Sex
Female	451	96	21.0 (17.3–25.4)
Male	462	115	24.9 (20.9–28.8)
Self-described	3	1	–
Age group, yr
18–24	95	22	22.6 (14.8–32.8)
25–34	233	49	20.9 (15.8–27.1)
35–44	247	54	21.5 (16.5–27.6)
45–54	157	36	23.2 (16.8–31.0)
55–64	94	28	29.6 (20.6–40.5)
≥ 65	80	22	28.1 (18.5–40.1)
Vaccinated^†
No	458	107	23.0 (19.1–27.4)
Yes, 1 dose	393	93	23.7 (19.5–28.6)
Yes, 2 doses	65	12	18.8 (10.7–30.9)
History of previous SARS-CoV-2 infection
Yes	88	69	78.1 (67.5–85.9)
No	600	81	13.5 (10.9–16.7)
Unknown	11	2	18.3 (4.3–52.8)
Median household income based on FSA, $
40 000–59 999	9	1	10.6 (1.3–52.4)
60 000–79 999	97	22	22.1 (14.4–32.4)
80 000–99 999	570	130	22.7 (19.1–26.6)
≥ 100 000	228	56	24.6 (19.0–31.3)
Essential worker
Yes	228	50	22.1 (16.8–28.4)
No	352	73	20.6 (16.3–25.5)
Prefer not to answer	113	21	18.3 (11.8–27.2)
Completed education
High school or less	121	31	25.4 (17.9–34.7)
College, trade, certificate	89	18	20.1 (12.6–30.5)
University degree	453	89	19.6 (16.0–23.9)
Prefer not to answer	30	6	19.4 (8.4–38.8)
Multigenerational household
Yes	125	30	23.1 (16.0–32.1)
No	451	88	19.7 (16.0–24.0)
Prefer not to answer	78	15	18.7 (11.1–29.8)
Location
Region of Peel	830	194	23.2 (20.2–26.5)
City of Brampton	742	178	23.8 (20.6–27.3)
City of Caledon	39	7	18.4 (8.6–34.9)
City of Mississauga	49	9	18.4 (9.4–32.9)
FSA income by household size categories
Lowest income	80	23	28.0 (18.5–39.9)
Category 2	121	22	18.0 (11.8–26.6)
Category 3	152	34	22.4 (16.0–30.5)
Category 4	117	21	18.1 (11.7–26.9)
Highest income	102	17	16.8 (10.4–26.1)

Note: CI = confidence interval, FSA = forward sortation area.
↵* Seropositivity estimates and 95% CI estimates from mixed models accounting for multiple responders per household. For overall model, the intraclass correlation coefficient = 0.17.
↵† Test interpretation for vaccinated individuals differed from that for nonvaccinated individuals; see the Methods section.

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Table 3:

Risk perception^*

Risk statement	N	Strongly disagree	Disagree	Neutral	Agree	Strongly agree	Prefer not to answer
COVID-19 poses a major threat to our community	583	10 (1.7)	4 (0.7)	34 (5.8)	149 (25.6)	370 (63.5)	16 (2.7)
The situation around COVID-19 is overexaggerated or overblown	582	154 (26.5)	190 (32.6)	106 (18.2)	61 (10.5)	48 (8.2)	23 (4.0)
I am at high risk of COVID-19 because of my location	583	41 (7.0)	89 (15.3)	147 (25.2)	185 (31.7)	103 (17.7)	18 (3.1)
I am at high risk of COVID-19 because of my housing situation	583	165 (28.3)	217 (37.2)	107 (18.4)	50 (8.6)	29 (5.0)	15 (2.6)
I am at high risk of COVID-19 because of my profession or my work	435	103 (23.7)	84 (19.3)	85 (19.5)	82 (18.9)	67 (15.4)	14 (3.2)
I am at high risk of COVID-19 because of my lifestyle (socializing or working in a crowded place)	583	189 (32.4)	199 (34.1)	100 (17.2)	47 (8.1)	34 (5.8)	14 (2.4)
If I get exposed to [SARS-CoV-2] or contract COVID-19, I am likely to have serious symptoms because of age and/or pre-existing conditions	583	136 (23.3)	162 (27.8)	149 (25.6)	73 (12.5)	40 (6.9)	23 (3.9)
If I get exposed to [SARS-CoV-2] or contract COVID-19, I am likely to need hospitalization because of my age and/or pre-existing conditions	582	138 (23.7)	173 (29.7)	163 (28.0)	49 (8.4)	36 (6.2)	23 (4.0)