What does “endemic” mean?
Epidemiologists say a disease is endemic when its presence becomes steady in a particular region, or at least predictable, as with seasonal influenza. But there’s no consensus on the conditions for meeting this benchmark. By this broad definition, endemicity doesn’t necessarily mean a disease is rare or common, mild or severe. For example, infection rates can still be high; they just have to remain static. Malaria, which is endemic in dozens of countries, mostly in sub-Saharan Africa, killed more than six hundred thousand people in 2020.
It’s easier to define endemicity in retrospect, when scientists are able to determine a baseline level because the disease has reached an equilibrium. This can be possible when the general population has protection from the disease, whether from vaccination or prior infection.
What does public health policy look like when a disease becomes endemic?
An endemic disease can still (and often does) require a robust policy response. The United States and many other countries urge individuals to get a flu vaccination each year, and they promote practices such as frequent handwashing and covering one’s mouth and nose when coughing or sneezing. For malaria and HIV, which is also endemic, various global initiatives are ongoing to develop more effective and accessible prevention tools. However, the responses are typically not as intense as those during a pandemic, when surging infections prompt the type of tight restrictions seen throughout the COVID-19 crisis.
Is COVID-19 becoming an endemic disease?
It’s too early to tell. Various government and industry leaders are promoting policy shifts in that direction, but officials from the World Health Organization (WHO) and other health experts warn against treating COVID-19 as an endemic disease. The course of the pandemic has rapidly changed with the emergence of new coronavirus variants, sending countries that had been experiencing monthslong lulls into a tailspin of infections and hospitalizations. “We don’t understand what the next shoe might be to drop with this virus,” the University of Minnesota’s Michael Osterholm tells CFR.
The world has made significant progress immunizing against COVID-19, but roughly one-third of people have yet to receive a vaccine dose. At the same time, health experts have raised concerns about waning effectiveness of certain vaccines, including those developed in China. There, Beijing continues to pursue a zero-COVID policy amid outbreaks of the omicron variant in major cities. So there is still a ways to go before achieving the kind of broad, global protection needed for endemicity.
Some countries are starting to treat COVID-19 as an endemic disease before others, depending on infection trends as well as on the social mood. “In terms of when a pandemic is over, it’s really a social term,” says CFR’s Jennifer Nuzzo. “We don’t have an epidemiologic criteria for the end of a pandemic.” Experts are looking to Portugal, which has the highest vaccination rate in Europe, as a model for living with endemic COVID-19: restrictions such as limits on large gatherings have been lifted, but many activities still require vaccination certificates and mask wearing. The new normal for international travel could likewise mean dialing back some requirements while keeping others.
What are the risks of prematurely thinking the pandemic is over?
The predominant risk is that the world will again find itself largely unprepared in the face of a more dangerous variant of the virus, and the possibility remains that a variant could emerge against which existing vaccines are ineffective. Complacency and government inaction contributed to the devastating surge of the delta variant across India in early 2021. The United States found itself scrambling as the omicron variant spread like wildfire at the end of that year, without sufficient tests and other supplies to manage the record infection levels. Now, U.S. health officials say the majority of Americans have been infected with COVID-19 at least once, but they caution people not to presume they have protection for the future. “What we want to make sure is that we’re prepared for what might come next,” said Xavier Becerra, secretary of the U.S. Department of Health and Human Services, at a CFR event. “Whether it’s a variant or a new form of disease, we want to learn from what COVID taught us.”
What should governments do until the world reaches an equilibrium with COVID-19?
The best-case scenario is that case surges from omicron and its subvariants indeed prompt the transition to endemic COVID-19, but that is just one scenario of many. Governments should be prepared to handle the worst possibilities, such as a case in which the world’s current vaccines are unable to defend against a new variant.
The WHO continues to advocate for increasing the global vaccination rate, as it will take at least ten months until 75 percent of people will have received at least one dose. Experts including Nuzzo and Osterholm also urge dedicating more resources to developing new vaccines, particularly genetic material–based ones (which have appeared to be more effective against new variants), as well as treatments. Scaling up testing capabilities and improving monitoring and surveillance networks are also high on the list, since having accurate, regular measurements of infection levels in a community allows officials to implement the most effective response.