Introduction

Timely notification of infectious disease outbreaks is one of the primary determinants of rapid response, and as such, is consistently one of the strongest predictors of outbreak containment and severity [1]. For outbreaks of potentially high-consequence pathogens, including those of unknown origin or with known epidemic potential, the international notification process becomes particularly relevant. Under Article 6 of the International Health Regulations (IHR) (2005), when outbreaks meet certain criteria (outlined in Annex 2), Member States are required to notify the World Health Organization (WHO); under Article 9, the WHO is also empowered to collect information from other sources such as news outlets or voluntary reports from Member States. The WHO then synthesizes and verifies this information, and shares updates with Member States and – in some cases – with the public.

In these cases, the most frequently used written outlet (and the only official public record of outbreak history curated by the WHO) is the Disease Outbreak News (DON), an online resource that has been curated since 1996 and captures thousands of outbreak reports from around the world. Reports in the DON usually capture the outbreak location, the causative agent (if known) or symptomology, and other critical information, such as case counts, details on response efforts, or WHO guidance. Between January 1996 and December 2019, a total of 2,789 reports were published in the DON, capturing developments in major epidemics like the 2014 West African Ebola epidemic, unusual events detected by syndromic surveillance, and everything in-between. The DON is generally understood to be an incomplete record of infectious disease outbreaks: the diseases and countries that are represented have shifted through time, reflecting not just the global history of outbreaks, but also the priorities of the WHO and the concerns of Member States. Over the last two decades, the DON has become dominated by major viral epidemics (such as MERS-CoV or Ebola virus outbreaks), while reports related to infectious disease of poverty (e.g., cholera) or isolated cases of novel pathogens have become more sparse [2].

Here, we revisit these trends, and explore how the WHO has used the DONduring the Covid-19 pandemic. We develop an incremental update to an existing dataset capturing the focus of these reports [2], with 242 new records from between 2020 and 2023. We explore how these reports documented the Covid-19 pandemic itself, as well as other major epidemics and smaller outbreaks during the same time frame.

Methods

Results

During the three-and-a-half-year period in which the Covid-19 PHEIC declaration was in place (2020 to 2023), the World Health Organization published a total of 242 reports in the Disease Outbreak News, describing outbreaks of 42 diseases in 89 countries (Fig 1).

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Fig 1. The global distribution of outbreak reporting and subject matter captured in the DON during the first four years of the Covid-19 pandemic.

Figure created in R, utilizing the rnaturalearth package, which draws upon a public domain map dataset [8].

https://doi.org/10.1371/journal.pgph.0004025.g001

Covid-19 in the DON

Reports related to the Covid-19 pandemic accounted for a small proportion (3%) of total outbreak reporting between 2020 and 2023: only 9 reports were published related to Covid-19, all from 2020. An initial cluster of five reports were published between January 5, 2020 and January 17, 2020. The first report, on January 5 – six days after the first ProMed-mail report on December 30, 2019 – noted a pneumonia outbreak of unknown etiology in China, which the WHO China Country Office had become aware of on December 31, 2019. Notably, this report included some of the first public information related to connections between initial case clusters and Huanan Seafood Wholesale Market. Subsequent reports provided a detailed update on the situation in China, including identification of the novel coronavirus (January 12); and updates on imported cases in Thailand, Japan, and South Korea (January 14, 16, 17, and 21). On January 21, the WHO also began posting daily situation reports on COVID-19 (instead of using the DON); this continued until August 16, 2020, when reports transitioned to a weekly basis.

Covid-19 did not reappear in the Disease Outbreak News again until November 6, 2020, when a report described a novel variant that had emerged on mink farms in Denmark, which had been transmitted from mink to humans, and had acquired mutations with an unknown level of associated risk; an update on this situation was published on December 3, 2020. Another novel variant of concern that had begun to spread rapidly in the United Kingdom was noted on December 12, 2020 (“SARS-CoV-2 VUI 202012/01,” now referred to as the Alpha variant). A final report was published on December 31, 2020, providing a global update of the first year of the pandemic, including references to the variants of concern that had been recently detected in Denmark, the United Kingdom, and South Africa (“501Y.V2,” now Beta), and the ongoing challenge of genomic surveillance. At the time of writing, this is the last time that the Disease Outbreak News was used to provide updates on Covid-19. Notably, no reports were published in response to the Omicron variant, which was significantly more transmissible than all other previous variants, and drove a global spike in cases, hospitalizations, and deaths (Fig 2).

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Fig 2. Weekly case counts and the timing of DON reports related to (A) the Covid-19 pandemic, and (B) the global clade II mpox epidemic.

Transparent orange circles indicate points where a report about the outbreak was published in the DON. Solid lines indicate the date of PHEIC declaration, and dashed lines indicate the end of the declaration.

https://doi.org/10.1371/journal.pgph.0004025.g002

Discussion

During the Covid-19 pandemic, the WHO was tasked with responding to an unprecedented number of concurrent health emergencies (as well as unprecedented levels of outbreak-related mis- and dis-information). The WHO has several means by which they are able to share information with both Member States and the public, including the Disease Outbreak News, the Weekly Epidemiological Record, situation reports, press releases, press conferences, social media posts, and non-public communications [5]. The decision to use any of these channels to share information – or equally, a decision not to do so – can prompt speculation about the risk assessment process and political pressures faced by the organization.

Over the last few years, the Health Emergencies Programme has made a concerted and public effort to improve transparency. During the pandemic, the WHO launched a new web portal for the Health Emergencies Programme, complete with a new search interface for the DON. The website also added language about the criteria used to decide which outbreaks are covered:

Disease Outbreak News (DONs) are published relating to confirmed or potential public health events, of:

• Unknown cause with a significant or potential international health concern that may affect international travel or trade;
• A known cause which has demonstrated the ability to cause serious public health impact and spread internationally;
• High public concern which may lead to disruption of required public health interventions, or could disrupt international travel or trade.

These criteria closely mirror the Annex 2 decision framework that States are required to use to assess potential public health emergencies of international concern under the IHR (2005). However, both Article 6 and 9 notifications from Member States are sometimes kept confidential per the wishes of the reporting State, and only a subset of these outbreaks are captured in the DON.

In February 2024 (since the conclusion of our study), the criteria for DON publication were clarified in significantly greater depth by a peer-reviewed article in BMJ Global Health, co-authored by members of the Health Emergencies Programme from WHO headquarters and every regional office [6]. This article shared the decision instrument used to trigger publication of DON reports (for the first time, to our knowledge), establishing that reports are published following Member State notifications if information on the outbreak is already public, or if there is a “need to disseminate authoritative and independent information as per Article 11 of IHR (2005).” The authors also note that other considerations include “a need for assistance from the international community” and “potential public interest.” The article also shared that States are made aware of outbreaks through the confidential IHR Event Information Site (EIS) system prior to any DON report, with only rare exceptions (e.g., when updates on an outbreak are already being regularly published), and that affected States are usually consulted when a DON report is being prepared.

The article by Lata et al. also provided important insights into the purpose that the DON is meant to serve, and how this has shaped the evolving content of the reports. Lata et al. state that “while DON reports are available to the public, the primary audiences are health professionals, subject matter experts, and the media.” The emphasis on providing these practitioner audiences with authoritative information is explicitly linked to the growing burden of mis- and dis-information that WHO faced during the pandemic:

…the rapid global expansion of the internet and the emergence of digital and social media have transformed the way in which society interacts with information. Information on acute public health events is more available and widely disseminated than ever before, but such information is not always verified or accurate. Furthermore, disinformation and misinformation are actively occurring, including during and in response to public health events. As an important counterbalance, DON reports aim to provide accurate, timely and authoritative information.

This suggests that specific mis-/dis-information may be considered under the stated criteria for report publication (i.e., a need to provide independent, authoritative information), and helps explain the growing detail of the reports. However, we note that this role for the DON is perhaps expanding or still being explored, given that the DON were only minimally used to address these issues for Covid-19 or mpox. Lata et al. also share that the DON format and process is periodically reviewed in an expert consultation, most recently in 2019. In the currently used format, reports are described as “highly standardised,” with seven sections used across all reports currently: situation at a glance; description of the situation; epidemiology of the disease; public health response; WHO risk assessment; WHO advice; and further information. They also observe that visualizations are used more commonly now, although “timely dissemination of DON reports takes precedence over the inclusion of new visualisations.”

The publication of this documentation is a significant advance in the level of transparency with which the DON is handled. This has clarified WHO’s perspective on the purpose served by the DON relative to their obligations under its Constitution and the IHR (2005), and confirms some long-standing suspicions, such as the deliberate use of the DON as a tool to draw attention to unfolding humanitarian crises [2]. It also underscores the unique value proposition of the DONs compared to, say, the all-purpose outbreak reporting in sources like ProMed-mail and HealthMap: they represent a first-order, qualitative risk assessment by the WHO related to which outbreaks have become, or are likely to become, emergencies.

As the WHO has become clearer about the purpose of the DON, the DON itself has become a more revealing record of the WHO’s internal process. Potentially high-consequence outbreaks that are subject to clear notification obligations under IHR Article 6 and Annex 2 – such as novel subtypes of influenza, viral haemorrhagic fever outbreaks, or poliomyelitis outbreaks – will likely continue to dominate the DON for the foreseeable future. The growing representation of climate-sensitive diseases similarly speaks to WHO’s recognition of their growing potential to cause disruptions to travel and trade in Africa and Latin America especially. The most interesting cases may be where WHO breaks from its own process: for example, the Alpha and Beta variants of Covid-19 were recorded in the DON, but the Omicron variant, which not only had a higher impact on human health, but also led to more significant international disruptions of travel and trade, was not. Decisions like these may simply be stochastic and may be reflective of high-consequence, limited-time frame decision-making, but they may also sometimes reflect the challenges faced by the WHO as global governance changes. For example, the Omicron variant led to an unprecedented breakdown of international norms around travel restrictions, which now poses an enduring problem in future outbreaks [7]. It remains to be seen how these new challenges will change the baseline process of information sharing during health emergencies—making the DON a more important resource than ever.