TABLE 2.

Effectiveness during the 2022/23, of two seasons of influenza vaccination 2021/22 and 2022/23.

	Controls a		Cases a		VE b with population age weighting (95% CI) (reference: unvaccinated both seasons)	VE b with population age weighting (95% CI) (reference: vaccinated 2021/22 only)
	Unvacc	Vacc	Unvacc	Vacc
All cases
2021/22 only	4793	1561	1493	294	37% (26%–47%)	Reference
2022/23 only	4793	581	1493	76	56% (42%–67%)
2022/23 and 2021/22	4793	3297	1493	428	57% (50%–63%)	32% (17%–44%)
A(H1N1)pdm09
2021/22 only	4793	1561	394	73	44% (25%–58%)	Reference
2022/23 only	4793	581	394	19	57% (28%–75%)
2022/23 and 21/22	4793	3297	394	132	54% (40%–65%)	17% (−16% to 41%)
A(H3N2)
2021/22 only	4793	1561	754	181	25% (6%–41%)	Reference
2022/23 only	4793	581	754	47	46% (19%–65%)
2022/23 and 2021/22	4793	3297	754	242	54% (42%–63%)	38% (19%–53%)
B
2021/22 only	4793	1561	210	14	65% (36%–81%)	Reference
2022/23 only	4793	581	210	3	86% (52%–96%)
2022/23 and 2021/22	4793	3297	210	13	83% (68%–91%)	52% (−11% to 79%)

Abbreviations: CI = confidence interval, unvacc = unvaccinated, vacc = vaccinated.

^a Cell counts include those with missing data for onset.

^b Adjustments were made for week of sample (spline), age group, scheme and clinical risk status.