TABLE 1

Clinical presentation of COVID-19 pneumonia during the first (1 February 2020 to 31 May 2020) and second (1 June 2020 to 1 June 2021) waves

Variables	First wave	Second wave	Wave	References
Age (years)	61±11.63	52±18.6	1°	[6, 7, 9, 12, 14, 16, 17, 19–22]
			2°	[14, 15, 17, 19–22]
Gender, male (%)	51	55	1°	[6–9, 14–17, 19–22]
			2°	[14, 15, 17, 19–22]
Symptoms]
Cough (%)	47.2	40.8	1°	[6, 8, 13, 14, 16, 19, 22]
			2°	[13, 14, 19, 22]
Fever (%)	46.6	55	1°	[6, 8, 14, 16, 19, 22]
			2°	[13, 14, 19, 21, 22]
Dyspnoea (%)	31.7	33.5	1°	[6, 8, 13, 14, 16, 19, 22]
			2°	[13, 14, 19, 22]
Fatigue, asthenia (%)	18.2	27	1°	[8, 16]
			2°	[22]
Acute kidney injury (%)	10.8	17	1°	[19]
			2°	[19]
Diarrhoea (%)	6	5	1°	[6, 8, 14, 16, 19]
			2°	[13, 14, 19, 22]
Vomiting (%)	2.7	5	1°	[14, 16, 19]
			2°	[14, 19]
Neurological symptoms (%)	0.6	0.7	1°	[14, 16]
			2°	[14]
Gas exchange]
P_aO₂ (mmHg)	69.7±21.36	65 (56–74)	1°	[8, 15]
			2°	[15]
P_aCO₂ (mmHg)	34.1±4.7	32 (28–84)	1°	[10, 15]
			2°	[15]
P_aO₂/F_IO₂ ratio (mmHg)	182±65.29	249±111	1°	[7, 9, 10, 15]
			2°	[15]
Respiratory rate (breaths per min)	23±4.8	28 (22–33)	1°	[8, 10, 15]
			2°	[15]
Saturation (%)	94±2.78	93 (89–97)	1°	[8, 15, 18]
			2°	[15]

Data expressed as mean±sd or median (interquartile range), unless otherwise stated. P_aO₂: arterial oxygen tension; P_aCO₂: arterial carbon dioxide tension; F_IO₂: inspiratory oxygen fraction.