Table I.

Hospital-acquired infection (HAI) rates during the Alpha and Delta waves

Alpha wave (Aug 2020–Apr 2021) HAI rates	Delta wave (May 2021–Sep 2021) HAI rates
Trusts using RPE (N=14)	Trusts using RPE (N=16)
Mean 11.9%	Mean 2.8%
Median 11.2% (IQR 8.4–14.4%)	Median 2.6% (IQR 2.2–3.7%)
Trusts not using RPE (N=109)	Trusts not using RPE (N=107)
Mean 14.7%	Mean 4.7%
Median 15.0% (IQR 10.4–18.2%)	Median 4.0% (IQR 2.7–6.0%)
Reduction in HAI rates	Reduction in HAI rates
Absolute: 3.0% (-0.3–6.3%)	Absolute: 1.4% (0.3–2.7%)
P=0.0713	P=0.0088
Patient level	Patient level
Overall proportion 14.3%	Overall proportion 4.2%
At trusts using RPE (N=31,163)	At trusts using RPE (N=8746)
Proportion 11.8%	Proportion 3.0%
At trusts not using RPE (N=224,156)	At trusts not using RPE (N=45,542)
Proportion 14.6%	Proportion 4.4%
Reduction in HAI proportion	Reduction in HAI proportion
Absolute: 2.7% (2.4–3.1%)	Absolute: 1.4% (1.0–1.8%)
Relative odds: 21.3% (18–24%)	Relative odds: 33.1% (24–42%)
P<0.00001	P<0.00001

RPE, respiratory protective equipment.