A Public Health Emergency of International Concern (PHEIC) have been declared for the following disease outbreaks:
1. Influenza A (H1N1)
Date of Declaration: April 25, 2009
Date of Undeclaration: August 10, 2010
Rationale:
• The widespread presence of the virus
• Virus containment unfeasibility at that stage
2. Poliomyelitis
Date of Declaration: May 5, 2014
Date of Undeclaration: Still remains as a PHEIC
Rationale:
• The risk of international spread of wild virus and the increasing evidence that adult travelers were contributing to the spread
• During the low season in 2014, there were 10 countries that are considered to have active transmission of wild poliovirus, and in contrast with previous years, there has already been a spread from three of these countries internationally
• Considering the large number of polio-free but conflict torn and fragile states which have severely compromised routine immunization services and are particularly at high risk of infection
3. Ebola (West Africa)
Date of Declaration: April 25, 2009
Date of Undeclaration: August 10, 2010
Rationale:
• The Ebola outbreak in West Africa constitutes an ‘extraordinary event’ and a public health risk to other States.
• The possible consequences of further international spread are particularly serious in view of the virulence of the virus, the intensive community and health facility transmission patterns and the weak health systems in the currently affected and most at-risk countries.
• A coordinated international response is deemed essential to stop and reverse the international spread of Ebola.
4. Zika
Date of Declaration: February 1, 2016
Date of Undeclaration: November 18, 2016
Rationale:
• The rising international concerns about Zika infections in South America, especially in Brazil.
• The postulated link to rising numbers of babies born with the congenital abnormality known as microcephaly.
5. Ebola (Democratic Republic of Congo)
Date of Declaration: July 17, 2019
Date of Undeclaration: June 26, 2020
Rationale:
• The concern about potential spread from Goma (as the city is a provincial capital with an airport with international flights.)
• The concern of the reinfection and ongoing transmission in Beni, which has been previously associated with seeding of virus into multiple other locations.
• The murder of two healthcare workers demonstrates continued risk for responders owing to the security situation.
• The lack of the global community contribution to sustainable and adequate technical assistance, human or financial resources for outbreak response, despite the previous recommendations for increased resources.
6. COVID-19
Date of Declaration: January 30, 2020
Date of Undeclaration: May 5, 2023
Rationale:
• Significant increases in numbers of cases and additional countries reporting confirmed cases and that there are still many unknowns, and human-to-human transmission has occurred outside Wuhan and outside China.
• WHO believes that it is still possible to interrupt virus spread, provided that countries put in place strong measures to detect disease early, isolate and treat cases, trace contacts, and promote social distancing measures commensurate with the risk.
7. Monkeypox
Date of Declaration: July 2022; August 14, 2024
Date of Undeclaration: May 2023; September 5, 2025
Rationale:
• The disease spread rapidly via sexual contact across a range of countries where the virus had not been seen before
• The emergence of a new clade of monkeypox, its rapid spread in eastern Democratic Republic of Congo (DRC), and the reporting of cases in several neighboring countries are very worrying.
• A coordinated international response is needed to stop outbreaks and save lives.
References:
WHO Director-General declares mpox outbreak a public health emergency of international concern. (2024, August 14). World Health Organization (WHO). Retrieved October 28, 2025, from https://www.who.int/news/item/14-08-2024-who-director-general-declares-mpox-outbreak-a-public-health-emergency-of-international-concern
Wilder-Smith, A., & Osman, S. (2020). Public health emergencies of international concern: a historic overview. Journal of travel medicine, 27(8), taaa227. https://doi.org/10.1093/jtm/taaa227
In your opinion, is there a disease or condition that may potentially lead to PHEIC in the future? Why?
In my opinion, measles is one disease that may potentially lead to PHEIC in the future. In the United States for example, measles has been officially eliminated since 2020 (meaning no measles spreading within the country and new cases are only found when someone contracts measles abroad and returns to the country). However, according to the CDC, a total of 1,618 confirmed measles cases have been reported as of October 21, 2025. There have been 43 outbreaks, and 87% of the confirmed cases (1,401 of 1,618) are outbreak-associated. Two fatalities due to measles have also been reported, the first time since 2015.
According to the WHO, least 95% of people in a community should be vaccinated in order to be protected through community immunity (herd immunity). In the US, however, vaccine coverage among US kindergartners has decreased from 95.2% during the 2019-2020 school year to 92.7% during the 2023-2024 school year. Vaccine hesitancy, fueled by misinformation and fake news, especially on social media, contributes to the continued decline in vaccine coverage.
Reference:
Measles cases and outbreaks. (2025, October 22). Measles (Rubeola). https://www.cdc.gov/measles/data-research/index.html
