Table 12.

Chi-square tests comparing feature significance in fully vaccinated versus unvaccinated individuals across the Alpha, Delta and Omicron waves.

Variant	Feature	Fully vaccinated (n = 11,556)	Unvaccinated (n = 39,646)	Odds ratio	Chi-square p-value
Alpha	Pneumonia	12	3648	1.99	0.032
Delta	Acute pharyngitis	44	248	1.69	< 0.01
	Acute respiratory failure	88	577	2.04	< 0.001
	Acute upper respiratory infection	86	371	1.28	0.045
	Hypoxemia	43	205	1.42	0.047
	Pneumonia	161	835	1.62	< 0.001
Omicron	Abnormal lung findings	128	127	0.62	< 0.001
	Acute pharyngitis	508	984	1.23	< 0.001
	Acute respiratory failure	287	604	1.34	< 0.001
	Acute upper respiratory infection	445	1176	1.72	< 0.001
	Cough	1043	1477	0.88	< 0.01
	Disorder of nasal cavity	270	561	1.32	< 0.001
	Dyspnea	359	444	0.77	< 0.001
	Pneumonia	452	891	1.255	< 0.001

p-value < 0.05 is significant.