TABLE 1

Adjusted Likelihood Ratios for individual symptoms when canonical symptoms are used in combination with an additional candidate symptom

Candidate added to CS	Study Day	Symptom	Adjusted Positive LR	Adjusted Negative LR	Candidate added to CS	Study Day	Symptom	Adjusted Positive LR	Adjusted Negative LR	Candidate added to CS	Study Day	Symptom	Adjusted Positive LR	Adjusted Negative LR
Abdominal pain	0	Fever	3.54	0.90	Appetite loss	0	Fever	3.68	0.90	Breathlessness	0	Fever	3.10	0.91
		Cough	1.48	0.90			Cough	1.29	0.94			Cough	2.12	0.82
		Anosmia	10.73	0.84			Anosmia	9.46	0.85			Anosmia	11.94	0.83
		Abdominal pain	1.19	0.98			Appetite loss	1.96	0.92			Breathlessness	0.31	1.09
Abdominal pain	2	Fever	3.04	0.80	Appetite loss	2	Fever	3.00	0.80	Breathlessness	2	Fever	3.69	0.76
		Cough	1.62	0.82			Cough	1.44	0.86			Cough	1.88	0.77
		Anosmia	4.42	0.81			Anosmia	4.39	0.81			Anosmia	5.80	0.78
		Abdominal pain	1.58	0.94			Appetite loss	2.22	0.84			Breathlessness	0.52	1.11
Abdominal pain	4	Fever	3.83	0.71	Appetite loss	4	Fever	3.52	0.73	Breathlessness	4	Fever	5.48	0.65
		Cough	1.33	0.87			Cough	1.22	0.90			Cough	1.56	0.80
		Anosmia	7.35	0.69			Anosmia	6.17	0.71			Anosmia	11.10	0.64
		Abdominal pain	1.04	0.99			Appetite loss	2.01	0.83			Breathlessness	0.34	1.31
Diarrhoea	0	Fever	4.08	0.89	Headache	0	Fever	3.22	0.91	Muscle aches	0	Fever	3.64	0.90
		Cough	1.26	0.94			Cough	1.27	0.94			Cough	1.29	0.94
		Anosmia	11.15	0.84			Anosmia	10.29	0.84			Anosmia	10.70	0.84
		Diarrhoea	2.88	0.93			Headache	1.37	0.89			Muscle aches	1.37	0.91
Diarrhoea	2	Fever	2.93	0.80	Headache	2	Fever	2.69	0.82	Muscle aches	2	Fever	2.83	0.81
		Cough	1.38	0.88			Cough	1.44	0.86			Cough	1.35	0.88
		Anosmia	5.43	0.79			Anosmia	4.29	0.81			Anosmia	4.75	0.80
		Diarrhoea	2.81	0.88			Headache	1.33	0.79			Muscle aches	1.76	0.72
Diarrhoea	4	Fever	3.82	0.72	Headache	4	Fever	3.43	0.73	Muscle aches	4	Fever	3.36	0.74
		Cough	1.31	0.87			Cough	1.20	0.91			Cough	1.21	0.91
		Anosmia	7.35	0.69			Anosmia	6.61	0.70			Anosmia	7.05	0.69
		Diarrhoea	1.08	0.98			Headache	1.30	0.76			Muscle aches	1.37	0.80
Nausea	0	Fever	3.54	0.90	Rhinitis	0	Fever	2.75	0.92	Sore throat	0	Fever	2.75	0.92
		Cough	1.53	0.89			Cough	1.28	0.94			Cough	1.28	0.94
		Anosmia	10.86	0.84			Anosmia	6.17	0.87			Anosmia	6.17	0.87
		Nausea	1.02	1.00			Rhinitis	2.57	0.80			Sore throat	2.57	0.80
Nausea	2	Fever	3.01	0.80	Rhinitis	2	Fever	2.95	0.80	Sore throat	2	Fever	2.95	0.80
		Cough	1.56	0.83			Cough	1.40	0.87			Cough	1.40	0.87
		Anosmia	5.08	0.79			Anosmia	3.07	0.85			Anosmia	3.07	0.85
		Nausea	1.30	0.97			Rhinitis	1.99	0.69			Sore throat	1.99	0.69
Nausea	4	Fever	3.81	0.72	Rhinitis	4	Fever	3.33	0.74	Sore throat	4	Fever	3.33	0.74
		Cough	1.31	0.87			Cough	1.06	0.97			Cough	1.06	0.97
		Anosmia	7.36	0.69			Anosmia	5.58	0.72			Anosmia	5.58	0.72
		Nausea	1.08	0.99			Rhinitis	2.29	0.58			Sore throat	2.29	0.58

LRs for individual symptoms in combination with other symptoms were calculated using the Spiegelhalter Knill-Jones method which adjusts for the dependency caused by symptom co-occurrence. Adjusted LRs for study days 0–7 are represented graphically in figure 2 and values for study days 0, 2 & 4 are presented here. For any combination of symptoms by a particular time-point, the adjusted LRs can be multiplied together to estimate effect on posttest odds. For example, on study day 0, a contact with fever and headache but without cough or anosmia has 3.22 × 0.94 × 0.84 × 1.37 = 3.90 times the odds of being infected compared to a contact where symptoms are unknown (see S4 for worked example). LR=likelihood ratio, CS=canonical symptoms.