How does Covid end? The world is watching the UK to find out | Laura Spinney

Cop26 in Glasgow gets underway this weekend. One collective action problem takes centre stage while another is fading away. Covid-19 was described as a rehearsal for the larger climate crisis problem. It is important to note that this pandemic has not ended. Covid-19 is a case study in how we need to work together.
For a while, the endgame was obvious: countries will adapt to Covid-19 rather than completely getting rid of it. An endemic is the technical term for a disease that was forced to be host indefinitely. This means that the disease-causing agent, the Sars-CoV-2 viral virus, is constantly circulating in the population. It causes periodic, but more or less predictable disease outbreaks. There are no countries that have entered the more tranquil waters of endemicity; they all remain in the white-knuckle phase of the pandemic.

Pandemics can be unpredictable and dangerous. The virus is still spreading to too many people, whether they are not vaccinated or have not yet been exposed to the Delta variant. Even if the virus does not make them all seriously ill, it will eventually find them most of the time.

Adam Kucharski, an infectious disease modeller at the London School of Hygiene & Tropical Medicine, told me that the pandemic will end when these pools of susceptibility are dry up. The gradual decline in immunity and the appearance of milder variants will continue to spread the diseases. It is uncertain when this will occur, as there are uncertainties about whether a person will be vaccinated or natural inoculation. There is also uncertainty about the virus's ability to create mild variants.

One thing is certain: The transition to endemicity in different countries will occur at different times. With its high vaccination rates and case numbers, it is not unreasonable to believe that the UK might be at the tipping point. This is why other countries are closely watching.

Although Delta is three times more transmissible than the original Wuhan variant, Sars-CoV-2-2, it has been dominating the UK since May. It has spread like wildfire in the UK since its freedom day, 19 July. Some scientists believe that the UK is about to enter its last pandemic wave and will then exit into an endemic phase next spring.

Others believe that the pandemic still has many waves to go, even in the UK. These waves could be smaller than they were in the past due to vaccines that have reduced the risk of infection and hospitalisation. Britons could still face another year of vulnerable people dying in large numbers. Others report debilitating effects from long Covid and health systems cracking under the strain.

All countries will eventually reach endemicity. However, the UK is moving very quickly and there will be a high human cost. There are other risks associated with allowing the virus to spread, even among highly vaccinated people. Robin Thompson, a modeller at the University of Warwick, told me that the high number of cases in the UK can only increase the likelihood of variants of concern.

Yet, we have not yet seen a Covid variant that can cause severe disease in fully vaccinated people. We are confident that we will not. Didier Trono, Virologist at the Ecole Polytechnique Fdrale de Lausanne, Switzerland, is cautiously optimistic about the possibility that SARSars–CoV-2 is reaching its limits in adaptability. New variants are still emerging, such as AY.4.2 which has recently spread to the UK. However, the disease is not significantly more severe than in early 2020. As immunity increases, so does the pressure on the virus to mutate. Vaccinologists are trying to mitigate this risk.

It's a race to finish. However, it might not be won easily. Vaccines protect us individually and not collectively at this stage. However, the future of endemic diseases will be determined collectively. Covid-19's future could be as mild or as severe as the common cold. But it could also be more serious. This future disease could require a more difficult response than that to the flu, which is a simple annual vaccination campaign. Kucharski said that although Covid is endemic, it could put an overwhelming strain on the health system in some years.

This is why the pandemic remains a problem of collective action. The coming wave, regardless of whether it is the exit wave, should be met by masks and other social distancing measures, as well as a high rate of booster shots for those who are eligible. This strategy must be as agile as the virus. It also requires that there are no compromises between the launch of vaccine doses in rich countries and booster campaigns in less developed ones. Although Sars-CoV-2 has been defeated, it is not yet tamed. It still has plenty to bite. Cop26 reminds us that this is just the beginning.

Laura Spinney, a science journalist, is the author of Pale Rider. The Spanish Flu of 1918: How it Changed the World