Public health emergency of international concern in the context of "Western African Ebola epidemic"

The global COVID-19 pandemic (also known as the coronavirus pandemic), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), began with an outbreak in Wuhan, China, in December 2019. Soon afterward, it spread to other parts of Asia and then worldwide in early 2020. The World Health Organization (WHO) declared the outbreak a public health emergency of international concern (PHEIC) on 30 January 2020, and assessed it as having become a pandemic on 11 March. The WHO declared the public health emergency caused by COVID-19 had ended in May 2023.

COVID-19 symptoms range from asymptomatic to deadly, but most commonly include fever, sore throat, nocturnal cough, and fatigue. Transmission of the virus is often through airborne particles. Mutations have produced many strains (variants) with varying degrees of infectivity and virulence. COVID-19 vaccines were developed rapidly and deployed to the general public beginning in December 2020, made available through government and international programmes such as COVAX, aiming to provide vaccine equity. Treatments include novel antiviral drugs and symptom control. Common mitigation measures during the public health emergency included travel restrictions, lockdowns, business restrictions and closures, workplace hazard controls, mask mandates, quarantines, testing systems, and contact tracing of the infected.

Severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) is a coronavirus that causes COVID-19, the respiratory illness responsible for the COVID-19 pandemic that began in late 2019. The virus previously had the provisional name 2019 novel coronavirus (2019-nCoV), and has also been called human coronavirus 2019 (HCoV-19 or hCoV-19). First identified in the city of Wuhan, Hubei, China, the World Health Organization designated the outbreak a public health emergency of international concern from January 30, 2020, to May 5, 2023. SARS‑CoV‑2 is a positive-sense single-stranded RNA virus that is contagious in humans.

SARS‑CoV‑2 is a virus of the species Betacoronavirus pandemicum (SARSr-CoV), as is SARS-CoV-1, the virus that caused the 2002–2004 SARS outbreak. Some animal-borne coronaviruses are more closely related to SARS-CoV-2 than SARS-CoV-1 is. The closest known relative is the BANAL-52 bat coronavirus. SARS-CoV-2 is of zoonotic origin; its close genetic similarity to bat coronaviruses suggests it emerged from such a bat-borne virus. Research is ongoing as to whether SARS‑CoV‑2 came directly from bats or indirectly through any intermediate hosts. The virus shows little genetic diversity, indicating that the spillover event introducing SARS‑CoV‑2 to humans is likely to have occurred in late 2019.

In May 2022, the World Health Organization (WHO) made an emergency announcement of the existence of a multi-country outbreak of mpox, a viral disease then commonly known as "monkeypox". The initial cluster of cases was found in the United Kingdom, where the first case was detected in London on 6 May 2022 in a patient with a recent travel history from Nigeria where the disease has been endemic. On 16 May, the UK Health Security Agency (UKHSA) confirmed four new cases with no link to travel to a country where mpox is endemic. Subsequently, cases have been reported from many countries and regions. The outbreak marked the first time mpox had spread widely outside Central and West Africa. The disease had been circulating and evolving in human hosts over several years before the outbreak and was caused by the clade IIb variant of the virus.

On 23 July 2022, the director-general of the WHO, Tedros Adhanom Ghebreyesus, declared the outbreak a public health emergency of international concern (PHEIC), stating that "we have an outbreak that has spread around the world rapidly, through new modes of transmission, about which we understand too little". A global response to the outbreak included public awareness campaigns in order to reduce spread of the disease, and repurposing of smallpox vaccines.

An epidemic of a new variant of clade I mpox (formerly known as monkeypox), called clade 1b, began in Central Africa at least as early as September 2023. As of September 2024, more than 29,000 cases have been reported, with over 800 fatalities (~3% fatality rate), nearly all in the Democratic Republic of the Congo. According to the European CDC: "The size of these outbreaks could be larger than reported due to under-ascertainment and under-reporting."

On 14 August 2024, the World Health Organization declared the epidemic a public health emergency of international concern.