Table 1.

Calculations of odds ratios using estimates of the prevalence of the risk group in the vaccinated population who did not become ill

Risk group	Prevalence of risk group in the vaccinated population who did not become ill, f	N1	N2	OR =(N1/N2) ×(1–f)/f
Men ≥ 56	0.061	26	38	10
Women 19–34	0.10	15	49	2.8
Autoimmune disease	0.03	10	54	6.0
Thymectomy for thymoma	0.0000015	4	19	140,000
Systemic lupus erythematosus (SLE)	0.0012	3	61	41
Pernicious anemia	0.016	1	63	0.99

N₁ = the number of subjects with the risk factor who became ill; N₂ = the number of subjects without the risk factor who became ill; OR = odds ratio. Frequency estimates for men ≥ 56 years of age and women between 19 and 34 years of age were obtained using the average from three references assuming equal numbers of male and female vaccinees. The remaining frequencies were those used in previous calculations by Monath (Table 3 in Reference ²). For the risk group, individuals thymectomized as treatment of thymoma, N₂ was reduced to 19 because following the report of that association in 2004,³ vaccination of such individuals was no longer recommended. Accordingly, the chance for accrual of additional thymectomized individuals became remote. In addition to the three cases of systemic lupus erythematosus (SLE), the two cases of Addison's disease, and the one case of pernicious anemia, one case each of autoimmune disease and YEL-AVD occurred with ulcerative colitis, myasthenia gravis, the combination of polymyalgia with hypothyroidism, and Crohn's disease (recent analysis raises the possibility that the latter entity may be an innate immune defect of macrophages and not autoimmune¹¹).