The outbreak of COVID-19 has infected 274 million people and taken 5.35 million lives as of December 20, 2021 [1]. The pandemic continues to challenge people’s physical and mental health with highly transmissible SARS-CoV-2 variants [2], resulting in increasing health disparities [3]. It has also had a great impact on the economy, increasing both poverty and unemployment [4]. The pandemic is making life harder for the vulnerable. The well-being of women especially deserves more attention given systematic barriers (e.g., sexism) in access to resources and their position as a majority of front-line healthcare workers [5]. The duration of this pandemic is unprecedented in modern times, leading to social unrest throughout the world.

The World Health Organization (WHO), founded in 1948, was the first United Nations agency devoted to global health affairs. The Constitution of the World Health Organization prescribes the rights and obligations of WHO to assist all peoples in attaining the highest possible level of health [6]. A central and historic duty of the WHO has been the management of the global regime for the control of international public health crises [7]. The International Health Regulations (IHR) approved in 2005 stipulate the responsibilities and obligations of WHO and member states in disease prevention, including defence and control of the international spread of disease and the provision of public health response measures [8]. Since then, as “the only source of legally binding international regulations for pandemic response” [9], the WHO has played an increasingly important role in preventing the spread of disease between countries as evidenced by its response to the 2009 pandemic influenza A(H1N1) virus, polio in 2014, Zika in 2014, Ebola in 2014 and 2018, and COVID-19 in 2020 [10].

The IHR, together with other instruments, such as the Global Outbreak Alert and Response Network (2000), the Pandemic Influenza Preparedness Framework (2011), the Public Health Emergency Operations Centre Network (2012), and the Contingency Fund for Emergencies (2015), also help WHO strengthen national public health systems [9]. In response to the pandemic, the WHO plays a key role in two aspects: sharing the Health Emergencies Programme and building the Health System. The WHO Health Emergencies Programme has made a considerable impact in the world, taking a stronger operational role. The Health Emergencies Programme includes preventing epidemics and pandemics and responding to health emergencies [11]. Throughout the programme, tests, treatments, and vaccines can be researched in a timely manner, essential supplies shipped to countries, and the healthcare workforce can be protected and trained. In 2019, the WHO responded to 55 emergencies in more than 44 countries and territories [10]. Several pandemics in the past have reminded us of the importance of preparedness, a strong health system that is resilient to shock, and the need to ensure systems that can maintain essential health services without financial hardship, especially during times of crisis. The WHO reiterated its commitment to supporting countries as they build universal health coverage. By 2019, 91 countries had improved patient safety, and 42 countries had implemented national healthcare workforce accounts [10].

During COVID-19, the WHO provides frontier support in leadership, policy dialogue and strategic support, as well as technical assistance and service delivery [12]. After the Wuhan Municipal Health Commission reported the cluster of atypical pneumonia cases, the WHO set up the Incident Management Support Team on January 1, 2020, to deal with the outbreak. At the IHR Emergency Committee meeting held on January 30, 2020, the WHO declared the novel coronavirus outbreak a Public Health Emergency of International Concern (PHEIC) and helped to establish national and international emergency coordination mechanisms [13]. The WHO has taken measures to respond to COVID-19 under a tight budget, such as convening an expert panel to develop interim best practice guidance for vaccine efficacy evaluations [14]. By December 31, 2020, 91% of countries had a COVID-19 preparedness and response plan, and 97% had a functional COVID-19 coordination mechanism [15]. The WHO also published the Strategic Preparedness and Response Plan aimed at controlling the spread of the virus and provided technical assistance, including deploying Emergency Medical Teams, establishing a global surveillance system, and working with partner laboratories [15].

Although Article 66 of the WHO Constitution requires legal capacity in the territory of each member [16] and the IHR states that “If a PHEIC is declared, WHO develops and recommends the critical health measures for implementation by the Member States during such an emergency” [7], these “soft laws” fall short of binding responsibilities [9], and the review committee has noted that “the IHR has no teeth” [17]. Some countries with weaker health systems are unable to follow the instructions of the WHO well [18]. The WHO has also received much criticism, including the irrationality of the WHO’s workplace health and safety guidelines on COVID-19 [19] and the inability to address the needs of older people [20]. The broad criticism, is somewhat unfair [10] since the failure to control the COVID-19 outbreak in the early stages was led by the inefficient early alarm and inadequate compliance of states with obligations under the IHR together [21]. A potential crisis of trust in the WHO is especially harmful given that the pandemic poses a threat to vulnerable people and regions. Nevertheless, it can be clearly realized that the WHO began to refashion itself as the coordinator, strategic planner, and leader of global health initiatives despite facing budget shortfalls and diminished status, especially given the growing influence of new and powerful players [22].

Only when people trust the WHO will they listen to its advice on pandemic prevention and control and promote global cooperation. It is worth noting that trust in social institutions is associated with the adoption of preventive behaviours during the pandemic [23,24,25,26], and health awareness and behaviours are undoubtedly necessary protective measures. A previous study among Americans found that trust in the competence of the WHO could play an important role in preventive health behaviours in addition to trust in the U.S. Centers for Disease Control and Prevention (CDC) [27]. Trust in the WHO has been under attack in recent years. In addition to the aforementioned, the level of public confidence in the WHO is influenced to some extent by the following.

The global political situation influenced people’s trust in the WHO because the WHO is funded by a combination of members' fees based on wealth and population and voluntary contributions. The news that then-President Donald Trump moved to withdraw the United States from the WHO on July 7, 2020 would call into question the WHO's financial viability and the future of its many programs promoting healthcare and tackling disease [28]. Second, the lack of a strong accountability mechanism, leading to the inadequate compliance of states with obligations under the IHR, probably caused people to lose confidence in the WHO [21]. For example, India refused to cooperate with the WHO to deal with H5N1 influenza in 2007 [29]. This is a clear violation of the IHR's obligation to minimally intervene and the member's obligation to cooperate, but there are no punitive measures under the IHR. Last, it is crucial to increase or at least maintain the quality and speed of health services or crisis management to maintain confidence in the WHO. A study in Korea demonstrated that the improvement in trust in central and local government is associated with proactive responses to the pandemic crisis, while the deteriorating trust in religious organizations is a consequence of their late approach to the crisis [30]. Given the important role of the WHO in global health governance, although many efforts have been made, a public health emergency that has not been effectively prevented and controlled, evidenced by increasing morbidity and mortality, is likely to lead to a decline in people's confidence in the WHO.

A longitudinal investigation researched the evolution of public trust in institutions during and after the 2009 pandemic in Switzerland and found that trust in almost all institutions decreased between the beginning of the outbreak and a year later. The magnitude of the decrease was particularly high for the WHO and the pharmaceutical industry benefiting from a relatively high level of initial trust [31]. Although some scholars who analysed people’s trust in science during the pandemic and found the overall level of trust in science remained unchanged after the first several months of COVID-19 [32], trustworthiness in COVID-19 information sources, such as the mainstream media, state health departments, the CDC, the White House, and a well-known university declined significantly in the United States [33]. However, considering the importance of the WHO during this pandemic, the effect of COVID-19 on public confidence in the WHO has yet to be well explored.

In this study, we used COVID-19 as a natural experiment to examine whether this pandemic has caused a crisis of confidence in the WHO. To be more specific, we adopted a difference-in-differences (DID) method that composited variations of trust in both time and space during COVID-19 to estimate the influence of COVID-19 on public confidence in the WHO. It can provide implications for the far-ranging effect of the public health emergency on people’s beliefs, including trust in leading international organizations. It can also shed light on the high priority that the WHO and other international organizations should place on the global development, the establishment and maintenance of public credibility in the face of emergencies and the prevention of crises in confidence.