Preference and willingness to pay of female college students for human papillomavirus vaccination in Zhejiang Province, China: A discrete choice experiment

Figures & data

Table 1. Attributes and levels

Attributes	Levels
Vaccine-related
Degree of protection	71% against cervical cancer
	71% against cervical cancer and 90% against genital warts
	90% against cervical cancer and 90% against genital warts
Duration of protection (years)	15, 30, 45
Risk of serious side effects	low level(1:100000), high level(1:10000)
Risk of mild side effects	low level (1:100), high level (1:10)
Cost (CNY)	1000, 2000, 4000, 8000
Service-related
Ways of making an appointment	on site, by phone, by the Internet, through school
Number of weeks waiting for vaccination	1, 4, 12, 24
Service time for vaccination	weekdays only, weekdays and weekends
Time to the nearest vaccination site	<30 minutes, 30–60 minutes, ≥60 minutes
Added cost (CNY)	0, 100, 200, 300

CNY indicates Chinese Yuan, and 1 CNY = 0.145 USD in 2019.

Figure 1. Examples of choice sets

Table 2. Characteristics of respondents

Characteristics	Description
Age median (interquartile range)	20 (19–21)
Average score of HPV knowledge * (standard error)	4.30 (0.08)
Average score of sociopsychological pressure ^† (standard error)	72.47 (1.01)
	N	%
Grade
First	220	25.9
Second	215	25.3
Third	169	19.9
Fourth	174	20.5
Fifth	72	8.5
Medical college
No	465	54.7
Yes	385	45.3
Parents’ education level
Below high school	349	41.1
High school and above	501	58.9
Living expenditure per month (CNY)
<1000	74	8.7
1000–2000	565	66.5
≥2000	211	24.8
Source of monthly living expenditure
Mainly from family	783	92.1
50% from family	38	4.5
Mainly from themselves	29	3.4
Ever had a sex life
No	721	84.8
Yes	129	15.2

CNY indicates Chinese Yuan, and 1 CNY = 0.145 USD in 2019.

* The scores of HPV knowledge range from 0 to 9, and a higher score refers to higher knowledge.

† The sociopsychological pressure scores range from 1 to 131, and a higher score indicates higher pressure.

Table 3. Regression coefficients of vaccine-related attributes and class membership model for two latent classes based on responses to a survey investigating preferences for human papillomavirus (HPV) vaccination among female college students in Zhejiang Province, China (n = 850)^*

	Coefficient	SE	z	P > z	95% CI
Class 1
Degree of protection
None (ref)
71% against cervical cancer	2.09	0.76	2.76	0.006	0.60	3.58
71% against cervical cancer and 90% against genital warts	2.99	0.75	4.01	0.000	1.53	4.45
90% against cervical cancer and 90% against genital warts	4.17	0.81	5.12	0.000	2.57	5.76
Duration of protection (per year)	0.04	0.01	5.17	0.000	0.02	0.05
Risk of serious side effects (per higher level of risk)	−0.25	0.12	−2.17	0.030	−0.48	−0.02
Risk of mild side effects (per higher level of risk)	−0.18	0.12	−1.59	0.112	−0.41	0.04
Cost (per 1000 CNY)	−0.13	0.03	−4.51	0.000	−0.19	−0.08
Class 2
Degree of protection
None (ref)
71% against cervical cancer	0.24	2.38	0.10	0.918	−4.42	4.91
71% against cervical cancer and 90% against genital warts	1.42	2.06	0.69	0.490	−2.62	5.47
90% against cervical cancer and 90% against genital warts	−0.16	2.84	−0.06	0.955	−5.72	5.40
Duration of protection (per year)	−0.06	0.05	−1.14	0.252	−0.16	0.04
Risk of serious side effects (per higher level of risk)	−1.16	0.97	−1.19	0.234	−3.06	0.75
Risk of mild side effects (per higher level of risk)	1.29	1.63	0.79	0.431	−1.92	4.49
Cost (per 1000 CNY)	−0.25	0.24	−1.03	0.305	−0.73	0.23
Class membership model
Score of HPV knowledge	0.37	0.09	4.02	0.000	0.19	0.54
Score of sociopsychological pressure	0.02	0.01	2.98	0.003	0.01	0.03
Age	−0.03	0.11	−0.24	0.810	−0.24	0.19
Living expenditure per month is 1000–2000 CNY (<1000 CNY as ref)	0.26	0.55	0.48	0.632	−0.81	1.34
Living expenditure per month is ≥2000 CNY (<1000 CNY as ref)	0.26	0.60	0.43	0.664	−0.92	1.44
50% of monthly living expenditure from family (mainly from the family as ref)	0.04	0.64	0.07	0.945	−1.20	1.29
Most of monthly living expenditure from themselves (mainly from the family as ref)	−0.21	1.16	−0.18	0.860	−2.48	2.07
High school and above of parents’ education (below high school as ref)	0.34	0.33	1.04	0.299	−0.30	0.98
Ever had a sex life (no as ref)	0.04	0.42	0.11	0.914	−0.77	0.86
Constant	−0.95	2.48	−0.38	0.702	−5.81	3.91

SE indicates standard error. CI indicates confidence interval. CNY indicates Chinese yuan, and 1 CNY =  0.145 USD in 2019.

*The model had a significantly better fit with 2 classes (BIC = 1644.7, McFadden R² = 0.20).

Table 4. Vaccine attribute levels and the predicted vaccine uptake for bivalent, quadrivalent, and nonavalent HPV vaccines in Zhejiang Province, China^*

	Bivalent HPV vaccine (Cecolin)	Bivalent HPV vaccine (CERVARIX)	Quadrivalent HPV vaccine (GARDASIL®)	Nonavalent HPV vaccine (GARDASIL 9)
Degree of protection	71% against cervical cancer	71% against cervical cancer	71% against cervical cancer and 90% against genital warts	90% against cervical cancer and 90% against genital warts
Cost (CNY)	1100	1800	2500	4000
Predicted vaccine uptake	11%	10%	22%	58%

*We assumed that the duration of protection and the risks of serious and mild side effects were the same among the four types of HPV vaccines. CNY indicates Chinese yuan, and 1 CNY = 0.145 USD in 2019.

Table 5. Regression coefficients of service-related attributes based on responses to a survey investigating preferences for HPV vaccination among female college students in Zhejiang Province, China (n = 733)^*

	Coefficient	SE	z	P > z	95% CI		WTP (CNY)
Ways of making an appointment
On site (ref)
By phone	0.422	0.138	3.07	0.002	0.152	0.691	241.7
By the Internet	0.355	0.162	2.19	0.029	0.037	0.674	203.6
Through school	0.509	0.140	3.63	0.000	0.234	0.784	291.4
Number of weeks waiting for vaccination (per week)	−0.044	0.006	−7.16	0.000	−0.056	−0.032	−25.0
Service in weekdays and weekends for vaccination (weekdays only as ref)	0.213	0.081	2.62	0.009	0.054	0.372	121.9
Time to the nearest vaccination site
<30 minutes (ref)
30–60 minutes	−0.299	0.121	−2.46	0.014	−0.536	−0.061	−171.1
≥60 minutes	−0.520	0.128	−4.08	0.000	−0.770	−0.270	−297.9
Added cost (CNY)	−0.002	0.001	−3.44	0.001	−0.003	−0.001

SE indicates standard error. CI indicates confidence interval. WTP indicates willingness to pay. CNY indicates Chinese yuan, and 1 CNY = 0.145 USD in 2019.

* Approximately 98.8% of all the respondents who chose to vaccinate in the vaccine-related choice set also chose to vaccinate in the service-related choice set. They were included in this analysis, and 9 respondents (1.2%) who chose not to receive the vaccine in service-related scenes were excluded to improve the analysis efficiency.