MERS-CoV seroconversion amongst Malaysian Hajj pilgrims returning from the Middle East, 2016–2018: results from the MERCURIAL multiyear prospective cohort study

Figures & data

Figure 1. The flow chart for participant enrolment, allocation, follow-up, and analysis.

Table 1. Demographic characterictics of Malaysian pilgrims during the 2016–2018 Hajj seasons.

Characteristics	Cohort 1 (2016)N = 366N (%)	Cohort 2 (2017)N = 905N (%)	Cohort 3 (2018)N = 811N (%)	OverallN = 2,082N (%)
Gender:
Male	168 (45.9)	410 (45.3)	370 (45.6)	948 (45.5)
Female	198 (54.1)	495 (54.7)	441 (54.4)	1134 (54.5)
Age Groups:
18–30	17 (4.6)	66 (7.3)	57 (7.0)	140 (6.7)
31–40	46 (12.6)	97 (10.7)	133 (16.4)	276 (13.3)
41–50	110 (30.1)	239 (26.4)	182 (22.4)	531 (25.5)
51–60	128 (35.0)	305 (33.7)	259 (31.9)	692 (33.2)
>60	65 (17.8)	197 (21.8)	179 (22.1)	441 (21.2)
Missing	0	1 (0.1)	1 (0.1)	2 (0.1)
*Underlying
Health Condition:	18 (4.9)	51 (5.6)	54 (6.7)	123 (5.9)
Asthma	1 (0.3)	1 (0.1)	2 (0.2)	4 (0.2)
CLD	13 (3.6)	16 (1.8)	22 (2.7)	51 (2.4)
CHD	2 (0.5)	3 (0.3)	1 (0.1)	6 (0.3)
CKD	56 (15.3)	148 (16.4)	121 (14.9)	325 (15.6)
Diabetes	91 (24.9)	261 (28.8)	207 (25.5)	559 (26.8)
HT	2 (0.5)	5 (0.6)	4 (0.5)	11 (0.8)
Cancer WIS	2 (0.5)	2 (0.2)	2 (0.2)	6 (0.3)

CLD = Chronic Lung Disease; CHD = Chronic Heart Disease; CKD = Chronic Kidney Disease; HT = Hypertension; WIS = Weakened Immune System.

*The underlying health conditions were based on self-reported pre-Hajj questionnaire.

Table 2. Common presenting respiratory symptoms among Malaysian pilgrims during the 2016–2018 Hajj seasons.

Symptoms	Cohort 1 (2016)N = 366N (%)	Cohort 2 (2017)N = 905N (%)	Cohort 3 (2018)N = 811N (%)	OverallN = 2,082N (%)
Fever	212 (57.9)	482 (53.3)	416 (51.3)	1110 (53.3)
Cough	336 (91.8)	810 (89.5)	764 (94.2)	1910 (91.7)
Sore throat	294 (80.3)	673 (74.4)	659 (81.3)	1626 (78.1)
Runny/Stuffy nose	274 (74.9)	623 (68.8)	636 (78.4)	1533 (73.6)
SOB	37 (10.1)	62 (6.9)	65 (8.0)	164 (7.9)
Muscle/Body ache	87 (23.8)	185 (20.4)	260 (32.1)	532 (25.6)
Headache	69 (18.9)	182 (20.1)	224 (27.6)	475 (22.8)
Fatigue	45 (12.3)	128 (14.1)	89 (11.0)	262 (12.6)
Vomiting	21 (5.7)	30 (3.3)	44 (5.4)	95 (4.6)
Diarrhoea	28 (7.7)	78 (8.6)	77 (9.5)	183 (8.8)

SOB = Shortness of breath.

The respiratory symptoms were based on self-reported post-Hajj questionnaire.

Table 3. Evaluation of pre- and post-Hajj IgG antibody for MERS-CoV using rS1 Enzyme-Linked Immunosorbent Assay (ELISA).

Year	Pre-Hajj N (%) (95% CI)		Post-Hajj N (%) (95% CI)		Seroconversion (≥ 4-fold increase in titre) N (%)
	Seronegative (ELISA OD ratio < 0.3)	Seropositive (ELISA OD ratio ≥ 0.3)	Seronegative (ELISA OD ratio < 0.3)	Seropositive (ELISA OD ratio ≥ 0.3)
2016 N = 318	311 (97.8) (0.08–0.09)	7 (2.2) (0.32–0.41)	306 (96.2) (0.08–0.09)	12 (3.8) (0.33–0.55)	1 (0.3)
2017 N = 905	882 (97.5) (0.08–0.09)	23 (2.5) (0.44–0.62)	880 (97.2) (0.08–0.09)	25 (2.8) (0.39–0.70)	5 (0.6)
2018 N = 752	732 (97.3) (0.06–0.07)	20 (2.7) (0.36–0.90)	728 (96.8) (0.06–0.07)	24 (3.2) (0.45–0.74)	6 (0.8)
Overall N (%) N = 1,975	1925 (97.5)	50 (2.5)	1914 (96.9)	61 (3.1)	12 (0.6)

*95% CI pertains to the range of ELISA OD ratios among the seronegative and seropositive samples.

Table 4. The association between post-Hajj serum seropositivity across history of camel exposure.

Variables		Post-Hajj Serum, N = 1,975
		Seronegative (OD <0.3)N (%)	Seropositive (OD ≥0.3)N (%)	Chi-square test	Fisher’s exact test
Visit Camel Farm	No	1,879 (95.9)	61 (3.1)	X^2 (1, N = 1,960) = 0.649
	Yes	20 (1.0)	0 (0)	P = 0.42	P = 1.00
Physical Contact with Camel	No	1,710 (96.4)	55 (3.1)	X^2 (1, N = 1,773) = 0.257
	Yes	8 (0.5)	0 (0)	P = 0.612	P = 1.00
Camel Milk Consumption	No	1,706 (96.2)	55 (3.1)	X^2 (2, N = 1,773) = 0.399
	Yes	12 (0.7)	0 (0)	P = 0.819	P = 1.00
Camel Urine Consumption	No	1,709 (96.4)	55 (3.1)	X^2 (1, N = 1,773) = 0.290
	Yes	9 (0.5)	0 (0)	P = 0.590	P = 1.00
Camel Meat Consumption	No	1,672 (94.3)	52 (2.9)	X^2 (1, N = 1,773) = 1.529
	Yes	46 (2.6)	3 (0.2)	P = 0.216	P = 0.17

Chi-square test and Fisher’s exact test showed no significance value, p > 0.05.

Table 5. Case findings of Twelve Seroconverted Hajj Pilgrims.

No.	Gender	Age (years)	Underlying health conditions	Symptoms experienced during Hajj	Exposure to camel/camel products	Pre-Hajj ELISA OD ratio (< 0.3)	Post-Hajj ELISA OD ratio (≥ 0.3)	Fold increase in ELISA OD ratio	MN* Assay (1:10 serum dilution)
1	Female	39	-	Fever, cough, sore throat, muscle or body ache, headache	No	0.0419	1.3642	32.6	Non-reactive
2	Female	67	Hypertension	Fever, cough, sore throat, runny and stuffy nose, muscle or body ache, headache	No	0.0773	1.6130	20.9	Non-reactive
3	Male	63	Hypertension	Fever, cough, sore throat, runny and stuffy nose	No	0.0379	0.7409	19.6	Non-reactive
4	Female	61	Hypertension	Fever, cough, sore throat, runny and stuffy nose, muscle or body ache, headache, diarrhea	No	0.0451	0.6246	13.9	Non-reactive
5	Female	57	–	Cough, sore throat, runny and stuffy nose	No	0.0409	0.3882	9.5	Non-reactive
6	Female	65	Diabetes, hypertension	Fever, cough, sore throat, muscle or body ache, headache	No	0.0641	0.4637	7.2	Non-reactive
7	Female	64	–	Fever, cough, sore throat, muscle or body ache	No	0.1157	0.8287	7.2	Non-reactive
8	Male	49	–	Fever, cough, sore throat, muscle or body ache	No	0.1160	0.8290	7.2	Non-reactive
9	Male	43	–	Fever, cough, sore throat, runny and stuffy nose, headache, diarrhea	No	0.0575	0.3697	6.4	Non-reactive
10	Male	67	–	Fever, cough, sore throat, runny and stuffy nose	No	0.0763	0.5000	6.5	Non-reactive
11	Female	64	Diabetes	Fever, cough, sore throat, runny and stuffy nose, headache	No	0.0724	0.4203	5.8	Non-reactive
12	Female	56	–	Fever, cough, sore throat, runny and stuffy nose, muscle or body ache, vomiting, diarrhea	No	0.1484	0.6264	4.2	Non-reactive

No underlying health condition is marked as “-”

*MN Assay = Microneutralization Assay