**5. Conclusions**

This study reveals the driving mechanism of public voice behavior and enriches the literature on voice behavior. First, based on the results of qualitative research, this paper employs the cognitive appraisal theory of emotion to explain the process of formation of public voice behavior under public health emergencies, via the stimulus-cognition-emotion-behavior model. Unlike voice within an organization, public voice on social media is a kind of self-motivated behavior free from the pressure of peers and organizational climate [4]. What is more, as the purpose of public voice is to improve social status quo, the cognitive appraisal theory of emotion is eminently suitable for explaining the formation of public voice behavior. As an external stimulus, a policy will have an impact on the public's cognitive processes, and prompt them to evaluate whether the policy can resolve a current issue and play a guiding role in the future development of society. When the public perceives the policy to be highly effective, they will have positive emotions; otherwise, they will have negative emotions. Take the Health Code policy as an example, if the public think that the policy can e ffectively contain the spread of the novel coronavirus and speed up the resumption of the normal activities, they will experience positive emotions, and vice versa. In accordance with the cognitive appraisal theory of emotion, emotional response will stimulate behavioral tendencies. The public's positive emotions will lead them to employ a promotive voice to expand the e ffectiveness and coverage of the policy, whereas the public has the tendency to use prohibitive voice to reduce the possible negative e ffects of a policy when they are not satisfied with its e ffectiveness. This result is consistent with previous studies that make a clear distinction between promotive voice and prohibitive voice, where the former is positive in tone and the later negative [68]. In this study, members of the public feeling positive emotions will voice to promote a policy and establish uniform standards throughout the nation, whereas those experiencing negative emotions will identify deficiencies such as implementation at the grassroots level. Second, this study clarifies the objects and types of public voice. Compared with employee voice and customer voice, the coverage of public voice is more extensive. Thus, for di fferent problems, the objects of public voice are also di fferent, which require separate analysis in each situation. Under this circumstance, the objects of public voice include two main bodies involved in policy-making: governments and enterprises. For the Health Code policy, the objects of public voice are the government, Alibaba, and Tencent. With regard to voice type, there is some similarity with the other two kinds of voice—public voice can also be divided into promotive voice and prohibitive voice. Finally, through qualitative research, this paper has attempted to reveal the role of public voice in policy evolution and product innovation, clarifying the promoting e ffect of public voice on societal improvement. The study emphasizes the importance of public voice via social media, suggesting that both governmen<sup>t</sup> and enterprises ought to attach more significance to public voice when making decisions.

Taking China's Health Code policy under COVID-19 as an example, this paper has constructed a dynamic mechanism for the e ffects of public voice on policy evolution. The study focused on the promotion of public voice for policy improvement and evolution in the late stages of policy-making. Public opinion contains information about demands and aspirations which is very valuable for decision makers. To absorb more public opinions and take into account public aspirations or priorities before policy formulation, previous research has paid much attention to the impact of public opinions at the pre-policy-making stage [65,66]. No studies have examined the impact of public voice on policy after its implementation. The development of social media not only provides a wider source of information for the public, but also builds a more convenient platform for the public to voice their opinions at any stage of policy formulation or implementation, thus having e ffect on policy. This study shows that after a policy is implemented, public voice is still of grea<sup>t</sup> value for policy evolution. However, this study divides policy evolution into three stages: policy formation, policy promotion, and policy optimization. It introduces changes in public policy utility perception and public voice content at di fferent stages, and constructs the dynamic mechanism of the e ffect of public advice on policy improvement based on the government's adoption of public advice to promote policy evolution and implementation.

To some extent, this study provides support for cooperative governance research. Cooperative governance has di fferent connotations in di fferent situations, and there are also some di fferences among participants. The formulation and evolution of policies under public health emergencies is an important practice of cooperative governance. Faced with a public health emergency, the government, enterprises, and citizens should form an open overall system to jointly govern social public a ffairs. The government, enterprises, and individuals play their own roles, participate and cooperate with each other to e ffectively reduce the negative impacts of a crisis and maintain the stable development of society. In this process, governments, enterprises, and the public are in a more equal position, and multi-agent participation is truly realized. Faced with COVID-19, Yaowen Wang, deputy director of Shenzhen Municipal Government Service Data Management Bureau, said the epidemic situation was a grea<sup>t</sup> challenge to the government's governance ability and level. In addition, the fundamental problem was laid in whether the whole society could be quickly mobilized and organized to participate in the prevention and control in a short period of time. As an organ of power, the governmen<sup>t</sup> is responsible for the formulation and implementation of policies. Enterprises participate in the formulation of policies, and provide products and services with technical advantages to assist with policy implementation. As for the public, in addition to regulating their own behaviors under the guidance of policies, they also provide feedback and voice on policies and enterprises' products and services. Take China's Health Code policy as an example, the governmen<sup>t</sup> is responsible for the formulation and implementation of the policy. Alibaba and Tencent are committed to the development and updating of the health code system and participate in the formulation of the policy standards. The public need to move around in strict accordance with the policy guidelines and actively provide voice. Under a public health emergency, public voice is an important way for public to participate in cooperative governance. It provides real-time feedback for policy, helping governmen<sup>t</sup> and enterprises to make decisions as quickly as possible and set aside more time to fight against emergencies. Further, public voice can facilitate the promotion of e ffective policy, improving prevention e fficiency. As a universal way of participating in cooperative governance, public voice via social media deserves more attention in the future.

Although this research makes several contributions, there are still some limitations. First, we studied the influence of public voice only on policy evolution and specific product innovation. As public voice is social-oriented, it will a ffect almost all social a ffairs and phenomena. Future research can explore the influence of public voice behavior in other respects. Second, this study revealed the generative mechanism of public voice behavior from the perspective of emotional cognition. As a self-oriented behavior, public voice may be triggered by other internal processes. Future research could explore the antecedents of public voice from di fferent perspectives. Third, this study was conducted under a public health emergency, COVID-19. As public emergencies take several forms, the results di ffer in di fferent situations. Future research might examine public voice in other contexts. Fourth, although many countries and regions have formulated corresponding policies in the context of public health emergencies, results from the study of China's Health Code policy under COVID-19 may not be fully applicable to other nations, and future research should be conducted in di fferent cultural contexts.

**Author Contributions:** Y.Y. conceived the idea of this study, Y.S. collected and analyzed data and wrote this paper. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Natural Science Foundation of China, gran<sup>t</sup> number 71972062; the National Natural Science Foundation of China, gran<sup>t</sup> number 71872058; the Fundamental Research Funds for the Central Universities, gran<sup>t</sup> number HIT.HSS.201842.

**Conflicts of Interest:** The authors declare no conflict of interest.
