1 Introduction
The Coronavirus (COVID-19) pandemic continues to be a global public health crisis and has caused huge economic and health damage worldwide. Mass vaccination aiming for herd immunity has been adopted as a national strategy in many countries to protect the population from being infected or developing severe conditions (Ayifah and Ayifah, 2022). Since December 2020, China has launched two rounds of vaccination programs and has been actively promoting the COVID-19 vaccine booster dose (GotPsRo, 2021). Domestically-manufactured vaccines by SinoVac or SinaPharm are provided free of charge to all citizens in light of the zero-COVID policy. Herd immunity of 75%–90% vaccination coverage was obtained in China, as well as in many other countries around the world (Anderson et al., 2020).
The effect of initial mass vaccination is limited as reflected by multiple COVID-19 resurgences worldwide and the recent outbreak in Shanghai. Immunity to COVID-19 can be undermined by the waning effect of vaccination, evolving variants, and virus breakthroughs. To cope with this challenge, the booster dose has been utilized by health authorities. Experts proposed an annual booster dose as a long-term strategy to control cross-border transmission and local outbreaks.
However, a long-term vaccination program is challenging both financially and socially. Providing vaccinations as public goods to a huge population is costly for the government given the current economic decline. Chinese National Healthcare Security Administration announced that the National Medical Fund would no longer subsidize routine nucleic acid amplification tests (Administration, 2022). Copayments or complete out-of-pocket charges may become a requirement in the future in order to sustain vaccination needs.
Vaccine hesitancy has been the major reason for the inability to control the COVID-19 infection (Iyer et al., 2022). Studies found that the success of long-term vaccination is closely related to the willingness to pay (WTP) for and willingness to vaccinate (WTV) against public viruses (Wane et al., 2019; Lai et al., 2020). WTP informs the maximum amount of money a customer is willing to pay for a specific good based on personal valuation and is commonly estimated using contingent valuation methods (CVM). WTV indicates the vaccination intention which can be used to predict actual vaccination behavior. The evidence surrounding WTP and WTV has assisted in policy development, vaccine pricing, government purchasing, and program design (Hynes et al., 2021). At the beginning of the COVID-19 epidemic, WTV and WTP were investigated in the Chinese population. Studies have reported the median WTP for COVID-19 to be CNY 100, 200, or 300 (Wang et al., 2021; Lin et al., 2020; Han et al., 2021) and the mean WTP to be CNY 130.45 and 254 (Qin et al., 2021; Wang et al., 2021). A higher price range of CNY 501–1,000 was once reported as the most preferred price for the general Chinese population (Zhang et al., 2021). On the other hand, WTV rates were estimated to be 83.5%, 77.4%, and 89.1% (Lin et al., 2020; Zhang et al., 2021; Han et al., 2021). Both WTP and WTV were largely affected by socioeconomic variables and variables measuring personal health beliefs, such as perceived risk and perceived benefit of vaccination in line with the health belief model (HBM) (Goruntla et al., 2021).
WTP and WTV varied with the severity of the epidemic (Wang et al., 2022). Early studies were conducted prior to the introduction of the COVID-19 vaccine to the market, therefore the findings may not bear much value to guide future vaccination policy. Now that the target population has been vaccinated and has personally experienced the effect of receiving or abstaining from vaccination, attitudes surrounding WTP and WTV were anticipated to change.
We hypothesized that an annual booster dose of the COVID-19 vaccine will become a national strategy in China for the next several years and that supplying vaccines as public goods may not be sustainable. WTP and WTV change over time, therefore reevaluation is required to inform the feasibility of an alternative financing scheme, as well as program design and adaptation. This study was conducted aiming to assess the WTP and WTV of the general Chinese population for the COVID-19 vaccine booster dose. This study is also designed to identify the significant factors contributing to the WTP.
4 Discussion
COVID-19 has had drastic economic, social, and public health implications, and continues to pose a significant threat worldwide. The COVID-19 vaccine booster dose has been implemented globally and is becoming a long-term public health safety measure. The WTP and WTV are important indicators of the population’s attitude toward continuous vaccination, and these measures fluctuate with the progression of the epidemic and its effect on policies. Therefore, continuous assessment of the WTP and WTV is of great significance. With this in mind, this study was conducted and found that the overall WTV rate was 86.74% in China given a 100% coverage rate and a 94.66% full vaccination rate. The median and mean WTPs were CNY 80 (USD 12.40) and CNY 149 (USD 23.02) respectively. Place of residence, AHI, vaccination status, perceived benefit of vaccination, and environmental peer pressure can significantly predict the concurrent WTP.
Our results appear encouraging, as both the actual vaccination rate and WTV are high. Compared to the WTV rates of 83.50%, 77.40%, and 89.10% in the early phase of the COVID-19 epidemic in China (Lin et al., 2020; Zhang et al., 2021; Han et al., 2021), the current WTV rate of 86.74% did not drop at a time that COVID-19 was under adequate control. Previous studies were conducted before the COVID-19 vaccine was available, and vaccination programs were not yet implemented. Theoretically, WTV at that time should have been higher because the strong wish to terminate the epidemic altogether would have predisposed more people to accept the vaccine. The WTV in our study represented the vaccination intention of vaccinated persons, who were more informed and realistic about the vaccination effect and witnessed the success of non-medical measures. The WTV rate remained satisfactory suggesting a promising prospect for the long-term vaccination strategy in China. As a developing country, the WTV rate of China was similar to that of other developing countries such as India and Kenya (Carpio et al., 2021; Goruntla et al., 2021), yet higher than that of developed countries such as Germany, the Netherland, and France (Neumann-Bohme et al., 2020).
Contrary to the theory and empirical evidence that the actual vaccination rate was always lower than the WTV rate (Wang et al., 2022), our study found the opposite. The full-schedule vaccination rate among our participants was 7.92% higher than the WTV rate. There were 61 subjects showing reluctance to vaccination, yet vaccinated anyhow. The high vaccination rate discovered in our study was generally consistent with the high acceptance of other personal protective measurements, such as mask-wearing and hand-washing in the Chinese population (Zhong et al., 2020). The extra vaccination above WTV indicates that external factors in addition to personal intention were taking effect. This is in line with the theory about the influence of external action plans on public willingness. An Indian study proved that governmental propagation of the COVID-19 vaccine enhanced the WTV rate significantly (Goruntla et al., 2021). This is most likely the case in China, as the Chinese government had implemented the zero-COVID policy, in contrast to “Live with COVID-19” in advanced countries (Kirby, 2022). Under the umbrella of the zero-COVID strategy, 1) vaccination was mandated to some institutionalized populations such as students and government officers (Ioannidis, 2021), 2) non-vaccination restricts people from essential activities like working in office or business traveling, 3) authorities provide powerful education about the severity and fatality of COVID-19 infection and benefit of vaccines (Zhang et al., 2021; Zhang et al., 2022), 4) some cities provided incentives to push for the vaccination, 5) last but not least, the vaccine is free. All these interventions would boost the vaccination rate as proven in other populations (Iyer et al., 2022).
Our study illustrated an expected, yet concerning, phenomenon that high vaccination status would dissuade a person from paying for a vaccine. The WTP estimated from our sample was lower than previously observed. The median WTP-average was CNY 80, below the median WTPs of CNY 100, 200, and CNY 300 previously reported for the Chinese population (Wang et al., 2021; Lin et al., 2020; Han et al., 2021). Likewise, the mean WTP in our study was CNY 149, lower than the mean WTPs of CNY 254 and 130 (Qin et al., 2021; Wang et al., 2021). One study published that the most preferred WTP range was CNY 501–1,000 (Zhang et al., 2021). Additionally, WTP was negatively associated with the number of shots. Full-schedule and booster-vaccinated persons would pay CNY 95 and 563, less than that of those who had received one shot only. This was further consolidated in multivariate analyses showing respondents boosted with the third shot were significantly reluctant to pay a higher price for the COVID-19 vaccine. This downward trend of WTP is not surprising in that the perceived current risk of infection was low at 14.36%, and the perceived risk in the next months was even lower at 7.92%. Studies have already shown that higher perceived risk is positively associated with WTP (Adigwe, 2021; Han et al., 2021; Zhang et al., 2021). Across the study period, the number of domestic cases were below 100, while sporadic outbreaks were confined to one or two cities (Organization, 2021), therefore, the urgency and value of vaccination was not sensed by individuals living in such environment. Our findings anticipate difficulties in changing from the currently free vaccine to a required co-payment or even a complete out-of-pocket payment if most people have been vaccinated. Targeted measures to improve public awareness of COVID resurgence and the importance of vaccine effect were suggested.
The HBM theory, which was specifically developed to study preventive interventions (Orji et al., 2012; Wong et al., 2020), has illustrated that personal belief is powerful in the vaccination decision-making process (Han et al., 2021). According to the multivariate analyses, the perceived benefit of vaccination and environmental peer pressure would enhance WTP. Those who strongly agreed with the benefit of vaccination are more than two times as likely to pay for high-priced vaccines than those who strongly disagreed. Those who would accept vaccination if others took it were twice as likely to pay for high-priced vaccines relative to those immune to peers’ behavior. Perceived benefit and susceptibility were known predictors for WTP in various populations (Han et al., 2021; Harapan et al., 2020). Additionally, interventions targeting these HBM constructs have improved the effectiveness of vaccination (Jones et al., 2012; Myers, 2017). Based on our findings, it makes sense to strengthen beliefs surrounding vaccination benefits and to leverage environmental pressure.
Regarding the relation between socioeconomic factors and WTP, our study found that people with lower AHI tend to pay less for the COVID-19 vaccine. The multivariate analyses confirmed the trend, and specifically, AHI < 40k was shown to be significantly associated with the lower WTP. Urban residents were 1.57 times as likely to pay a high vaccine price. These findings were consistent with local and international studies that economically disadvantaged people were unwilling to pay irrespective of other factors (Wang et al., 2021). This highlights the need to consider the affordability of the COVID-19 vaccine, especially in low-middle-income countries. If the COVID-19 vaccine was priced at CNY 149 (the grand mean WTP in our study), over 70% of the sample and families with AHI < 210K were unwilling to pay (Figure 2; Table 2). This can be extrapolated to one billion people considering the size of Chinese population (EBoNBoSo, 2022). Domestically made vaccines have been priced at CNY 200 or 234 per dose to local governments and individual customers (Times, 2020; Author Anonymous, 2020). It seems that the COVID-19 vaccines have been over-priced and exceeded common affordability.
WTP is useful, informative evidence for a government to utilize in the provision of public goods and decision-making surrounding issues such as financing, pricing, and subsidization. In the scenario that public goods transit to private goods, WTP can inform the affordability of the public, especially in low- and middle-income countries (LMICs) where public financing is difficult. In Nigeria, only a quarter of respondents were willing to pay for vaccination, and half of the respondents were not willing to pay more than USD1.20 (Adigwe, 2021). Studies from other LMICs have reported mean WTPs of USD 30.66, 57.20, and 85.92 respectively in Malaysia, Indonesia, and Vietnam (Harapan et al., 2020; Wong et al., 2020; Vo et al., 2021), as well as WTP ranges of USD 6.81-13.62 for India and USD 49.81-68.25 for Kenya (Carpio et al., 2021; Goruntla et al., 2021). Our estimate of CNY 149, which is equivalent to USD 23.09 according to the exchange rate in 2021, has seemingly confirmed that China still belongs to the class of LMIC, and that the affordability of the population needs to be considered. On the other hand, high-income countries reported much higher mean WTPs of USD 232 and USD 318.76 for the COVID-19 vaccine in Chile and the USA respectively (Catma and Varol, 2021; Cerda and Garcia, 2021). The WTP varies greatly across the countries indicating the uneven affordability of different populations. This heterogeneity may form a barrier in the global war on the COVID-19 epidemic (Acharya et al., 2021).
Some advantages of our study were of note. The biggest advantage distinguishing this study from others could be that the validity of WTP is high. We used randomization and averaging to minimize bias. Respondents were first randomly allocated to PS or IBG method, and then further randomized to one of three IBG biding algorithms with different starting-price. The WTPs by two CVM methods were averaged and analyzed. It turned out that the IBG derived significantly higher WTPs than the PS, though methodologically expected (Frew et al., 2004). Moreover, the WTPs by two CVM methods from the same person had a poor agreement, even in extremely opposite directions observed in 10 cases. Within IBG itself, the mean WTPs were CNY 435, 329, and 309 for IBG800, IBG170, and IBG20 respectively, reflecting the “anchoring effect” inherent in this method. All these facts mean that random allocation and data averaging are necessary and have reduced the methodology-induced bias in estimating the true WTP. Another advantage is that WTP and WTV for the booster dose at the time of adequate epidemic control were rarely reported. Our study filled the gap and allowed policy-makers to keep track of WTP and WTV trajectories.
This study has some limitations. The sample size of 543 was considered small to represent the national population. In this regard, a study using Monte Carlo simulation showed that a sample size of 400 is sufficient to produce a valid WTP with little impact from the number of bidding prices (Judez et al., 2000). The representativeness may also be undermined by our sampling methods and the online-survey format. Respondents with high internet utilization may be systematically different from the general population. Snowballing sampling is limited to reaching a wide population base. Considering that two rounds of vaccination programs have been completed, and the effectiveness and safety of the vaccine are generally known to everyone, the IBG scenario did not provide data or facts about the vaccine. The social benefit of vaccination and the negative effect of non-vaccination were delineated instead. This needs to be considered when our results were compared with the early studies which were conducted before the vaccine was available. Finally, a cross-sectional study was unable to substantiate a causal relationship.