Modelling the potential public health impact of different vaccination strategies with an omicron-adapted bivalent vaccine in Thailand

Figures & data

Figure 1. Model structure. 1a. Markov model. 1b. Decision tree.

Table 1. Base case results and expanding vaccination to other age and risk groups.

	Base Case: Age ≥65 Years and High Risk			Age >50 Years and High Risk			Age >50 Years, Age 6 Mo-5 Years, and High Risk
	No Vaccination	Vaccination	Incremental Impact	No Vaccination	Vaccination	Incremental Impact	No Vaccination	Vaccination	Incremental Impact
Booster doses administered	0	5,528,406	5,528,406	0	7,678,662	7,678,662	0	8,349,194	8,349,194
Deaths	13,815	12,912	903	13,815	12,730	1,085	14,585	13,441	1,144
Hospitalizations	1,128,833	1,092,255	36,578	1,128,833	1,075,350	53,484	1,710,701	1,613,591	97,110
Infections	4,508,935	4,411,339	97,596	4,479,958	4,353,385	126,573	5,856,083	5,636,496	219,587
Direct medical costs (million BAHT)	118,107	114,988	3,119	118,107	113,781	4,327	160,331	153,339	6,992
Testing cost (million BAHT)	35,120	34,486	634	35,120	34,297	823	46,321	44,919	1,402
AE management cost (million Baht)	0	2	−2	0	3	−3	0	3	−3
Inpatient treatment cost (million BAHT)	49,344	47,483	1,861	49,344	46,655	2,690	69,442	65,246	4,196
Outpatient treatment cost (million BAHT)	782	768	14	782	766	16	982	954	28
Post-COVID condition treatment cost (million BAHT)	32,861	32,249	612	32,861	32,061	800	43,587	42,218	1,369
Indirect costs (million BAHT)	480,247,970,015	469,658,775,609	10,590	480,247,970,015	465,599,263,050	14,649	480,253,419,348	465,604,243,259	14,649
Productivity loss due to illness (million BAHT)	479,590	469,025	10,565	479,590	464,985	14,605	479,590	464,985	14,605
Productivity loss due to death (million BAHT)	443	420	23	443	401	42	448	406	42
Education loss (million BAHT)	215	213	2	215	213	2	215	213	2

*Base case coverage: standard-risk population: 0% (5–64 years), 72.6% (65–74 years), and 61.9% (≥75 years); high-risk population: 0% (5–11 years), 1.5% (12–17 years), 58.2% (18–29 years), 69.3% (30–49 years), 73.6% (50–64 years), 72.6% (65–74 years), and 61.9% (≥75 years).

Table 2. Base case results and expanding vaccination in the standard-risk population.

	Base case: Age ≥ 65 and High Risk*	Standard Risk Coverage: 25%	Standard Risk Coverage: 50%	Standard Risk Coverage: 75%
Booster doses administered	5,528,406	16,224,650	26,920,894	37,617,138
Deaths averted	903	1,189	1,474	1,760
Hospitalizations averted	36,578	99,035	161,493	223,950
Infections averted	97,596	352,150	606,704	861,258
Direct medical costs averted (million THB)	3,119	8,834	14,549	20,263
Indirect costs averted (million THB)	10,589	34,831	59,073	83,315

*Base case coverage: 0% (5–17 years), 36.1% (18–29 years), 36.1% (30–49 years), 32.1% (50–64 years), 23.6% (65–74 years), and 23.6% (≥75 years).

Standard-risk population comprises individuals aged <65 years with no comorbidities.

Table 3. Alternative base case results and expanding vaccination in the standard-risk population.

	Base case: Age > 50 and High Risk*	Standard Risk Coverage: 25%	Standard Risk Coverage: 50%	Standard Risk Coverage: 75%
Booster doses administered	7,678,662	16,702,290	25,725,918	34,749,547
Deaths averted	1,085	1,229	1,373	1,518
Hospitalizations averted	53,484	102,791	152,098	201,405
Infections averted	126,573	358,587	590,601	822,614
Direct medical costs averted (million THB)	4,327	9,102	13,878	18,653
Indirect costs averted (million THB)	14,649	35,733	56,817	77,901

*Base case coverage: standard-risk population: 0% (5–49 years), 72.6% (65–74 years), and 61.9% (≥75 years); high-risk population: 0% (5–11 years), 1.5% (12–17 years), 58.2% (18–29 years), 69.3% (30–49 years), 73.6% (50–64 years), 72.6% (65–74 years), and 61.9% (≥75 years).

Standard-risk population comprises individuals aged 5–49 years with no comorbidities.

Table 4. Alternative base case results and expanding vaccination in the standard-risk population.

	Base case: Age 6 mo-4 years or >50 years and High Risk*	Standard Risk Coverage: 25%	Standard Risk Coverage: 50%	Standard Risk Coverage: 75%
Booster doses administered	8,349,194	17,372,823	26,396,451	35,420,079
Deaths averted	1,144	1,288	1,432	1,577
Hospitalizations averted	97,110	146,417	195,724	245,031
Infections averted	219,587	451,600	683,614	915,628
Direct medical costs averted (million THB)	6,992	11,767	16,543	21,318
Indirect costs averted (million THB)	14,649	35,733	56,817	77,901

*Base case coverage: standard-risk population: 25% (6 months-4 years), 0% (5–64 years), 72.6% (65–74 years), and 61.9% (≥75 years); high-risk population: 25% (6 months-4 years), 0% (5–11 years), 1.5% (12–17 years), 58.2% (18–29 years), 69.3% (30–50 years), 73.6% (50–64 years), 72.6% (65–74 years), and 61.9% (≥75 years).

Standard-risk population comprises individuals aged 5–49 years with no comorbidities.

Table 5. Scenario analysis results varying the disease burden in analysis of the full Thailand population.

	Delta Variant (July 2021-September 2021)	Omicron Variant (January 2022-March 2022)*
Booster doses administered	17,429,198	17,429,198
Deaths averted	1,517	1,280
Hospitalizations averted	61,186	101,289
Infections averted	334,171	342,546
Direct medical costs averted (million THB)	7,014	8,994
Indirect costs averted (million THB)	44,286	44,980

*base case.

Figure 2. Tornado diagram of the deterministic sensitivity analysis of the total incremental cost savings.