Table 2. Protection against severe COVID-19 associated with vaccination status with or without prior SARS-CoV-2 infection^a in each follow-up period during SARS-CoV-2 Omicron variant dominance, Scania county, Sweden, 2021 week 52 – 2022 week 11 (n = 593 cases; n = 5,930 controls).

Vaccination and infection history	Follow-up period
	Omicron BA.1 2021 w52–2022 w1		Transition 2022 w2–3			Omicron BA.2 2022 w4–11
	Protection	95% CIb	Protection		95% CIb	Protection	95% CIb
0 – 1 dose	Reference		Reference			Reference
0 – 1 dose + prior infection	81	0–98	85	0–98		54	0–87
2 doses	91	79–96	70	41–85		57	17–78
2 doses + prior infection	91	57–98	92	59–98		53	0–82
≥ 3 doses	94	83–98	92	83–96		82	64–91
≥ 3 doses + prior infection	100	NAc	85	47–96		88	64–96

CI: confidence interval; COVID-19: coronavirus disease; OR: odds ratio; SARS: severe acute respiratory syndrome coronavirus 2.

^a SARS-CoV-2 infections included were at least 90 days before the case date recorded in the study period.

^b Protection was estimated as 100 x (1– OR).

^c Not possible to estimate CI.

Estimates were obtained from conditional logistic regression with adjustment for comorbidities (0, 1, ≥ 2).

The following vaccines were used during the study period: Comirnaty (BNT162b2 mRNA, BioNTech-Pfizer), Spikevax (mRNA-1273, Moderna), Vaxzevria (ChAdOx1-S, AstraZeneca).