“The Spanish flu did mutate into a milder form that became part of a seasonal cycle, but this was over a hundred years ago and human life was very different then.”įor a start, the novel SARS-CoV-2 coronavirus is a different beast from the flu, HIV and Zika viruses, and we aren’t yet able to predict how it is likely to evolve. “Certainly in our living history we don’t have anything like SARS-CoV-2, so it is a little difficult to work out exactly how things will play out in the long run,” Tildesley argues.
Looking back over previous examples, such as the 1918 Spanish flu pandemic, the HIV epidemic of the 1980s or the more recent Zika outbreak, provides few clues as to what lies ahead for COVID-19.
Alternatively, the virus may evolve into a less harmful form and take up a place in our regular repertoire of grotty colds, although this is by no means guaranteed. “It’s very hard to determine when we’ll see a shift to endemicity as there are multiple different things at play.”Įven if rates do stabilise again, there is always the risk of novel variants emerging that could set off a new wave of infections. “The difficulty we have with SARS-CoV-2, the virus that causes COVID-19, is that because it is a new virus our baseline was zero, so we don’t know what the norm is,” explains Mike Tildesley, professor of infectious disease modelling at the University of Warwick. Perhaps the biggest challenge with figuring out whether COVID-19 has settled into an endemic phase is knowing what a ‘normal’ rate of infection looks like once we get there. “Even if we did nothing to control SARS-CoV-2 or any other new virus, it would still shift from a pandemic to endemic status in the end, because almost everyone would eventually catch it and have some level of immunity, assuming they survive.” What is normal, anyway? “The endemic state is a balance between the natural transmissibility of the pathogen and our immunity, and that’s what keeps it in check,” he says. “It’s one that persists at a fairly constant level, unless something drastically changes like a vaccination programme or a problematic new variant.”Īs Woolhouse explains, this constant infection rate is achieved by reaching a high level immunity across the population, often referred to as herd or community immunity, either through natural infection or vaccination (or both). “You could say that an endemic disease is just part of the human condition, part of our lives,” says Mark Woolhouse, professor of infectious disease epidemiology at the University of Edinburgh.
This doesn’t necessarily mean mild or harmless - endemic diseases still kill many hundreds of thousands of people every year worldwide - but something we’ve learned to live with and mitigate against. The dictionary defines a pandemic as an outbreak of a disease that occurs over a wide geographic area, such as multiple countries or continents, and typically affecting a significant proportion of the population.īy contrast, an endemic disease is one that is consistently present in certain populations or regions, usually with a relatively constant rate of infection (such as malaria or measles as we know them now) or predictable seasonal waves like ‘flu. So, are we still in the throes of a pandemic, or are we moving to a stage where COVID-19 has become endemic and accepted as part of daily life? And what can we do to get there faster? What does it mean to go from pandemic to endemic? Yet plenty of people are still catching COVID-19, being hospitalised and even dying every week, in the UK and elsewhere. Widespread vaccination in some parts of the world and the lifting of restrictions in many countries make it easy to feel that we’re moving into a new phase of living with the virus. A few years later, and we’re probably all sick of hearing it. How close are we to the ‘new normal’, where COVID-19 is endemic, relegated into the background of daily life, and what will it take to get us there?Īt the end of 2019, most people - with the exception of epidemiologists and public health experts - wouldn’t have had much call to use the word ‘pandemic’ in daily life. More than two years after the COVID-19 pandemic first swept the globe, we’re still learning to live with this novel disease.
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