Herd immunity now seems impossible. Welcome to the age of Covid reinfection

<span>Photograph: Leon Neal/Getty Images</span>
Photograph: Leon Neal/Getty Images

What do I wish I had known in early 2020? Other than to buy shares in toilet paper, Zoom and vaccine companies, I wish I had known that a safe and effective vaccine against severe disease and death from Covid-19 would arrive within a year – and that reinfection would nevertheless become a major issue in managing the disease. These two facts would have shifted the UK government’s response, and allowed for a more unified scientific front in advising them.

At the very beginning of the pandemic, several governments – including in Sweden, Netherlands and the UK – believed the best path through this crisis was to allow a controlled spread of infections through the population, especially the young and healthy, in order to reach some static state against the virus. The idea was that “the herd” who got infected would protect a more vulnerable minority.

This concept came from our approach to other vaccines, in which we inoculate the majority of children against, for example, measles, mumps and rubella (MMR) in order to protect those who cannot be vaccinated due to health conditions. If Sars-CoV-2 only infected people once, or vaccinated people couldn’t catch Covid (ie if infection or vaccination resulted in lifelong immunity) then herd immunity would be possible. By now, we would have eliminated Covid completely in the richer world where seroprevalence – estimates of antibody levels – are more than 90%, and in Britain as high as 98%.

However, this is far from the position we’re in. The rising number of documented reinfections, sometimes occurring relatively quickly after the initial infection, as well as the high number of infections with the Omicron variant among the fully vaccinated, means that herd immunity is likely impossible – even if seroprevalence hits 100%. Relying on herd immunity to manage Covid-19 rather than on the strategies of east Asian countries to suppress it until a vaccine was available was a gamble that Britain took early in March and unfortunately lost. Especially given the presence of variants, Sars-CoV-2 will just keep circulating and reinfecting people.

It’s not all bad news, though. Vaccines have largely blunted the virus’s ability to kill, and its destructive impact on health services. However, the problem we face has shifted from mass mortality to a question of how to keep essential services and workplaces running. Covid-19 is not yet mild enough to be treated like the common cold because it makes people so ill that they cannot work. This has created widespread disruption for airlines, border control, supermarkets, schools, hospitals, police forces and even Apple stores. And it’s worth pointing out that while Omicron is milder than Delta, it is still hospitalising and killing people, especially those who are unvaccinated, the clinically vulnerable (including some for whom vaccines are ineffective), and elderly people. Waning immunity is also an ongoing concern, as is making sure boosters are provided at the right time.

Watch: What do we know about new Covid subvariant and what are symptoms?

So governments are in a tricky situation. It’s clear that it’s better that no one is infected with this virus. Increasing evidence has been produced that shows the negative impact Covid-19 infection has on the lungs, heart and brain or even the development of diabetes. Long Covid prevalence estimates are eye-wateringly high.

On the flipside, how does one avoid infection while also wanting to be part of society and mix with others? Humans are social creatures who enjoy being around other people and participating in group activities – whether dancing in nightclubs or singing in church. Asking people to restrict this for a certain period of time made sense in order to allow vaccines to be rolled out, and for clinicians to develop better protocols for treatment and understand the disease better. But now we face a variant in Omicron that is incredibly transmissible to the point that even South Korea has abandoned test and trace, and China is struggling with incredibly strict lockdowns to bring cases down. Where does this leave us?

As a group of fellow scientists and I suggest in a new paper for Nature Medicine (REF), several steps can help manage this seemingly intractable situation.

First, governments must use the triad of testing, therapeutics (in particular, rapid antiviral pills) and vaccines to manage Covid-19 and replace the cruder non-pharmaceutical interventions of 2020 with scientific progress. Testing is particularly important given lateral flow tests are excellent at quickly detecting infectious individuals and preventing outbreaks in workplaces. The end of free testing is a major concern in managing this disease and avoiding future lockdowns. It is better for one person to be off work isolating then be forced into work where they infect dozens of others, leading to staff shortages and preventable illness. Meanwhile, vaccines must be rolled out to all parts of the world to reach the 70% target across all countries. This will have a substantial effect in reducing the disability and deaths that Covid-19 waves cause.

Second, rapid response plans must be prepared in order to react to a gamechanging new variant which could alter the trajectory of the pandemic, just as Alpha, Delta and Omicron did. This is now scientists’ main fear, and as we’ve seen, governments may only have days to pull together data and respond.

Third, rapid testing to detect infectiousness and one-way masking should continue to be used to protect those most at risk of infection (healthcare workers and social care workers), as well as those most at risk of severe health outcomes (people in care homes and in vulnerable groups).

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Finally, long Covid hasn’t received the attention it deserves. An increasing number of people who are unable to return to work, or suffering from chronic illness, will be a major burden on healthcare services as well as the economy; and of course there is the core issue of the loss of a healthy and active life in terms of daily happiness and living free of suffering. Developing treatments for this condition is imperative given that avoiding Covid-19 infection is increasingly difficult. We must support those suffering and find ways of reducing their pain.

Just as avoiding Covid-19 infection must be balanced against the importance of socialising, our response to the pandemic shouldn’t overshadow other major health issues on the horizon. These include the cost of living crisis; the number of children going hungry and living in cold, damp conditions and in poverty; the rise in child obesity and physical inactivity which has an impact on the development of chronic health issues; the mental health toll the pandemic has taken on adolescents in particular; the educational recovery needed after widespread school closures; and finally addressing the burnout of healthcare workers in the NHS. Entering the age of reinfection means Covid has truly embedded itself in our world, and it must be viewed as part of the wider picture of human wellbeing and public health.

  • Prof Devi Sridhar is chair of global public health at the University of Edinburgh

  • Join Devi Sridhar for a Guardian Live online event on Monday 25 April. She will talk to Nicola Davis about Covid-19 and the lessons we can learn from our handling of the pandemic. Book here