January 7, 2022, by Brigitte Nerlich

Endemic confusion

A few days ago, I saw this tweet by Bill Hanage and smiled: “For some reason there seems to be a lot of talk about endemicity again. For the avoidance of doubt, omicron is not endemic right now in much the same way that the moon is not a hamster”. I read many of the almost 200 comments and was rather amused. But then I asked myself: What is ‘endemicity’? What does ‘endemic’ actually mean?

I got even more confused when I read, the same day, an article quoting the renowned German virologist Christian Drosten. The article claimed: “…that data from other countries suggesting Omicron infections were milder could take the pandemic into an ‘endemic situation’ more comparable to a common cold or flu virus. ‘Of course, it is a good situation if you have a virus that no longer makes you ill but transmits easily so that it can seek out and find all of the immunity gaps among the population and still trigger regular updates in immunity,’ Drosten said.”

So what does endemic really mean and what has it come to mean? And why is Omicron not endemic, at least not yet? And would it be good or bad if it was….?

I am not sure I have found all the answers to these questions. For this post I rummaged around responses to Hanage’s tweet, spun out from there to some other material in the media and also wove in some information from a great thread by Ellie Murray that I remembered from a few months ago. But first. What can one find by just searching for definitions of ‘endemic’ in a naive sort of way?

Trying to find good definitions

The Oxford English Dictionary defines the word ‘endemic’ as “Constantly or regularly found among a (specified) people, or in a (specified) country… Of diseases: Habitually prevalent in a certain country, and due to permanent local causes”. Medical dictionaries have similar definitions, such as “Endemic: A characteristic of a particular population, environment, or region. Examples of endemic diseases include chicken pox that occurs at a predictable rate among young school children in the United States and malaria in some areas of Africa.”

This article made things a bit clearer: “An epidemic is actively spreading; new cases of the disease substantially exceed what is expected. More broadly, it’s used to describe any problem that’s out of control, such as ‘the opioid epidemic.’ An epidemic is often localized to a region, but the number of those infected in that region is significantly higher than normal. For example, when COVID-19 was limited to Wuhan, China, it was an epidemic. The geographical spread turned it into a pandemic. Endemics, on the other hand, are a constant presence in a specific location. Malaria is endemic to parts of Africa. Ice is endemic to Antarctica.” [Ha, I wondered, for how long?]

When searching for endemic and Covid-19, I found that there seems to be a general consensus emerging amongst scientists that Covid-19 might eventually become endemic in some parts of the world where nations have not managed to suppress it. Some see this as a desirable state. And some, for example Drosten, see the Omicron variant, which transmits fast and wide, but is, so far, not leading to long hospitalisations, as a stepping stone towards reaching that state. Others see Omicron as a spanner in the works….

My questions is: What happens when we reach that state of Covid-19 being endemic? Malaria is endemic in Africa, but ‘living with it’ is no fun, and despite still using lots of public health measures (which haven’t miraculously been abandoned when malaria became ‘endemic’) there are still millions of deaths. This is, it seems to me, not the scenario painted around the word ‘endemic’ in some parts of popular discourse. So what do we see there? I should stress that much more research is needed here.

Listening in to ongoing discussions

At the beginning of the pandemic there were lots of discussions around whether the new coronavirus would be similar to other endemic viruses which cause the common cold or the flu, for example. Then Covid-19 caused by the coronavirus SARS-CoV-2 was declared a pandemic and discussions began about whether over time it would become endemic.

The phrases ‘learning to live with it’ or just ‘live with it‘ were used quite commonly, especially in regions of the world where the virus has continued to spread, circulate and evolve. The advent of Omicron at the end of 2021 has brought this discourse more to the fore, as some people hope Omicron may hasten this process of Covid-19 becoming endemic.

At the beginning of the pandemic some said Covid-19 was like the flu, now they hope that it will become like the flu.

As I can’t do a large-scale media-analysis of the use of ‘endemic’ for this post, I went back to the responses to Hanage’s hamster/moon tweet and looked more closely at what words and concepts people associated with ‘endemic’ in their responses, apart from ‘living with’ or ‘learning to live with’.

Being over

There is a yearning for the pandemic to be ‘over’ and people think once the virus is endemic, that state will be reached – the pandemic will have come to an ‘end’. Outside Hanage’s tweet and replies there are many articles and tweets about the end of the pandemic. One thread in particular is very good, by Ellie Murray, one of many epidemic science communicators.

She points out that “In the beginning of any pandemic, we have 4 options for what could happen:
1) continually occurring disease, with small or large surges
2) local elimination of disease
3) global eradication of disease
4) complete extinction of the pathogen”.
All options are hard, but option 2 has been achieved for measles and option 3 for smallpox. Option one is ‘endemic’ disease. “This is easier short-term but it’s the hardest *long-term*.”

Being acceptable

Going back to the responses to the Hanage tweet, I found that the word ‘accept’ was used, as in: we have to accept and live with the virus. This corresponds to some definitions of endemic by scientists who say that endemicity is reached when we reach “some sort of acceptable state” (there are also discussions of what acceptable numbers of deaths are, but I can’t go into that here). But as Ellie Murray said in her thread on endemicity: “What level is ‘acceptable’ differs from place to place, over time & between diseases, and it may not always be explicit, but when a disease is endemic, there is a threshold!” I’d recommend you read the whole thread, together with another one by Aris Katzourakis who had a bit of very informative rant about the ubiquitous statement that “covid will just become endemic”. [He has now, 24 January, written this up as a piece for Nature. Read it!]

Being inevitable

One responder to Hanage’s tweet pointed to views that reaching endemicity is ‘inevitable’ and we should just get on with it. Others in the media equate endemic with ‘inescapable’ and a ‘regular part of live’; that it is part of a new type of life we have to learn to ‘endure’….etc.

Being harmless

People also want to believe that the virus is mutating in such a way that it’s becoming only an ‘annoying cold’. Here ‘endemic’ is virtually equated with ‘harmless’, something that was more easy to do when it started to emerge that the illness triggered by Omicron may be ‘mild‘. But endemic does not necessarily mean mild. It means that a disease is prevalent in a region. As one contributor to the Hanage discussion said: “Life-threatening illnesses can be endemic. That’s not a good thing.”

Being normal

Nevertheless, there is a wholly different discourse to explore out there alongside the ‘living with it’ one, and that is the ‘it’s a new normal’ one. But I can’t go into that here.


The meaning of endemic seems to be, for some, that this is the best we can hope for (acceptable, inescapable, mildly annoying or harmless and a new kind of normal), as we can’t eliminate or eradicate the virus anyway. The problem with this framing is that we may not even try to eliminate the virus anymore, at least here in the UK. One tweeter responding to Hanage’s tweet warned: “The real danger of this line of thinking is that people think redefining it as ‘endemic’ will somehow change its transmission and burden”…

The other danger is that the discourse around ‘endemicity’ will be dragged into the discourse around ‘freedom’, just like the mask and vaccination discourses, with ‘supporters’ of endemicity claiming it will free us from what they may see as state bioterrorism or something similar, while others might reflect on the cost that some in society would have to pay to get to that new state of freedom. This might entrench pandemic polarisation in society. But there are more direct problems with framing endemicity as relatively harmless…

As the Director of the Wellcome Trust, Jeremy Farrar, said: “Endemicity doesn’t mean that there will be no more infections, let alone illnesses and deaths. It also doesn’t mean that future infections will cause milder illness than they do now. Simply put, it indicates that immunity and infections will have reached a steady state. Not enough people will be immune to deny the virus a host. Not enough people will be vulnerable to spark widespread outbreaks.” So we have to be careful about what we wish for.

And what about this endemicity? Is that ‘steady state’ anywhere in sight? Perhaps not. As Sarah Zhang, a renowned science writer, pointed out in The Atlantic just at the start of Omicron: No one knows exactly what endemic COVID will look like, but whatever it looks like, this—gestures at the current situation—ain’t it. COVID is not yet endemic. There is little doubt that the coronavirus will get there eventually, when almost everyone has been vaccinated or infected or both, but right now we are still living through a messy and potentially volatile transition period. Cases are ticking up again. A new variant is afoot. The challenge ahead is figuring out how to manage the transition to endemicity, however long it takes.”

Managing the transition means taking care of people; protecting people – and how much protection they need and how much protection states can provide depends on the level of endemicity that they have to deal with or allow to happen. But managing the transition also means managing information better at a time when dis/misinformation is ‘endemic’. As Hanage said in another tweet “In any case the term endemism needs to be carefully deployed”. We need epidemic communicators to keep an eye on what things people do with the word ‘endemic’ and also help people like me who are still confused about it all. And I am still not sure why the endemicity talk seems to have won over the elimination talk in our neck of the woods.

Added 1 February: Additional resource: An article in Nature and a podcast by Aris Katzourakis on the issue

Added 8 February: Additional resources: An article by Jacob Steere-Williams in Medical Humanities on the history of the word and on endemic fatalism. And a two-part interview with Ellie Murray for World Socialist Website in which she clarifies what ‘endemic’ really means and how the word has been politicised…

Added 11 February: Additional resource: Here is Ben Zimmer with some etymology!

Added 16 February: Additional resource: Article in Science on ‘endemic delusion’ by Kelly Servick


Image: Pixabay


Posted in coronavirusinfectious diseasesScience Communication