Effectiveness of COVID-19 vaccines against SARS-CoV-2 Omicron variants during two outbreaks from March to May 2022 in Quzhou, China

Figures & data

Figure 1. The enrollment of infections and close contacts in two outbreaks from March to May 2022 in Quzhou, China.

Table 1. The definition of vaccination status according to the technical vaccination recommendations for COVID-19 vaccines in China (First Edition).

Vaccination status	Definition
Unvaccinated	No history of COVID-19 vaccination before the last SARS-CoV-2 exposure date.
Partial vaccination	Comply with any of the following criteria:
	(a) One dose of adenovirus vector vaccine administered but less than 14 days before the last SARS-CoV-2 exposure date;
	(b) Only received one dose of inactivated vaccine;
	(c) Received two doses of inactivated vaccine but less than 14 days before the last SARS-CoV-2 exposure date;
	(d) Received two doses of recombinant protein (CHO cell) vaccine;
	(e) Received three doses of recombinant protein (CHO cell) vaccine but less than 14 days before the last SARS-CoV-2 exposure date.
Full vaccination	Meet any of the following criteria:
	(a) One dose of adenovirus vector vaccine completed more than 14 days before the last SARS-CoV-2 exposure date, but not boosted;
	(b) Received two doses of inactivated vaccine more than 14 days before the last SARS-CoV-2 exposure date, but not boosted;
	(c) Received three doses of recombinant protein (CHO cell) vaccine completed more than 14 days before the last SARS-CoV-2 exposure date, but not boosted;
	(d) Two doses of adenovirus vector vaccine administered less than 7 days before the last SARS-CoV-2 exposure date;
	(e) Three doses of inactivated vaccine administered less than 7 days before the last SARS-CoV-2 exposure date;
	(f) Two doses of inactivated vaccine administered and boosted with one dose of adenovirus vector vaccine less than 7 days before the last SARS-CoV-2 exposure date;
	(g) Two doses of inactivated vaccine administered and boosted with one dose of recombinant protein (CHO cell) vaccine less than 7 days before the last SARS-CoV-2 exposure date.
Booster vaccination	Accord with any of the following criteria:
	(a) Received two doses of adenovirus vector vaccine more than 7 days before the last SARS-CoV-2 exposure date;
	(b) Received three doses of inactivated vaccine more than 7 days before the last SARS-CoV-2 exposure date;
	(c) Received two doses of inactivated vaccine and boosted with one dose of adenovirus vector vaccine more than 7 days before the last SARS-CoV-2 exposure date;
	(d) Received two doses of inactivated vaccine and boosted with one dose of recombinant protein (CHO cell) vaccine more than 7 days before the last SARS-CoV-2 exposure date;

Table 2. Vaccine effectiveness for partial, full, and booster immunization with COVID-19 vaccines by age group and virus type during two outbreaks in Quzhou, China.

Group	Case				Exposed persons				VE (95%CI), %
	Un- vaccinated	Partial vaccination	Full vaccination	Booster vaccination	Un- vaccinated	Partial vaccination	Full vaccination	Booster vaccination	Partial vaccination	Full vaccination	Booster vaccination
Age group
Under 3 years	2	0	0	0	62	0	2	0	NA	NA	NA
3–17 years	1	1	24	0	84	18	1,847	5	NA	NA	NA
18–39 years	2	0	12	18	382	54	1,157	2,022	NA	NA	NA
40–59 years	6	0	7	53	227	25	1,006	3,795	NA	73.7(20.9–91.2)	47.2(0–77.5)
60–79 years	3	0	3	12	95	10	173	933	NA	45.1(0–89.1)	59.3(0–88.7)
Over 80 years	1	0	5	1	33	5	36	64	NA	NA	48.4(0–96.9)
Virus type
BA.1	2	0	6	5	88	13	211	550	NA	NA	60.0(0–92.4)
BA.2	13	1	45	79	795	99	4,010	6,269	38.2(0–92.0)	31.4(0–63.1)	22.9(0–57.3)
Total	15	1	51	84	883	112	4,221	6,819	47.4(0–93.1)	28.9(0–60.2)	27.5(0–58.3)

*NA stands for incalculable or non-statistical.

Figure 2. Cox proportional-hazard regression curves among immune population in COVID-19 outbreaks of SARS-CoV-2 Omicron variant in Quzhou, China.

Table 3. The relative risk and results of Cox proportional-hazard regression model among immune population in COVID-19 outbreaks of SARS-CoV-2 Omicron variant in Quzhou, China.

Group	Case	Exposed persons	AR(%)	RR(95%CI)	B**	p value	Hazard ratio (95%CI)
Overall	151	12035	1.25
Gender						.27
Male	77	6682	1.15	Ref
Female	74	5353	1.38	1.20(0.87–1.65)	0.15	.39	1.16(0.83–1.64)
Vaccination status						.66
Unvaccinated	15	883	1.70	Ref		<.001
Partial vaccination	1	112	0.89	0.53(0.07–4.02)
Full vaccination	51	4221	1.21	0.71(0.40–1.28)	−0.30	.77	0.74(0.10–5.46)
Booster vaccination	84	6819	1.23	0.72(0.42–1.26)	−1.11	.27	0.33(0.05–2.40)
Virus type						.49
BA.1	13	862	1.51	Ref
BA.2	138	11173	1.24	0.82(0.46–1.45)	0.59	.07	1.80(0.95–3.39)
Age group						<.001
3–17 years	2	64	3.13	Ref
18–39 years	26	1954	1.33	0.43(0.10–1.83)	−3.64	<.001	0.03(0.01–0.06)
40–59 years	32	3615	0.89	0.28(0.07–1.19)	−3.24	<.001	0.04(0.02–0.08)
60–79 years	66	5053	1.31	0.42(0.10–1.74)	−2.78	<.001	0.06(0.03–0.15)
Over 80 years	18	1211	1.49	0.48(0.11–2.09)	−1.00	.06	0.37(0.13–1.03)

*B is the regression coefficient.

Data availability statement

The data that support the findings of this study are available from the corresponding author on reasonable request .