Outbreaks declared as PHEIC
1. 2009 H1N1 influenza pandemic (“swine-flu”) in 2009
2. Ebola virus disease in West Africa outbreak during 2014-2016
3. Zika virus and associated clusters of microcephaly/neurological disorders in 2016
4. Coronavirus disease 2019 (COVID-19) in 2020
Why do PHEICs raise such concerns?
Here are the major reasons why a PHEIC declaration is so significant:
1. International spread risk: If a pathogen in one country can spread to others (through travel, migration, trade) and threaten global health, that elevates the concern. Because of the connectivity of modern travel, local outbreaks can become international very fast.
2. Unexpected behavior: such emergencies involve either a new pathogen or a known pathogen behaving in an unusual way (e.g., new transmission routes, new geography, new risk groups).
3. Seriousness of health impact: The outbreak must pose a significant threat, such as high morbidity or mortality potential, large numbers of people affected, or severe complications. For example, COVID-19 caused large global disruption, health system strain, and many deaths.
4. Need for coordinated international response: A key part is that the event requires action beyond individual national responses, e.g., coordination, resource mobilization, global surveillance, travel/trade considerations, research acceleration (vaccines/therapeutics), etc.
5. Public health systems & global equity: Many PHEICs highlight the vulnerability of weaker health systems, capacity gaps, and the need to support countries that may be underserved. The declaration helps direct resources and attention where needed.
Because of all of the above, a PHEIC is more than a label: it’s a trigger for enhanced global preparedness, response coordination, surveillance, research, and resource mobilization.
What disease or condition could become a PHEIC in the future — and why
In my opinion, a likely future PHEIC could arise from a novel influenza virus originating in animals (such as avian or swine strains) that mutates to allow efficient human-to-human transmission. For these reasons, influenza viruses evolve rapidly, cross species barriers easily, and spread quickly through global travel. If a new strain emerges against which humans have little or no immunity, it could cause widespread illness and death before vaccines or treatments are available. Such a scenario would meet all PHEIC criteria.