In late October 2022, epidemiologists and infectious disease experts around the world began to notice an unsettling trend.

As the epidemiologist Adam Kucharski explained in a Twitter thread, there was a new wave of Covid-19 afoot – but it was going largely unnoticed. Today the alarming spikes of Covid-19 deaths and hospitalisations, which we had all become familiar with during the grim days of 2020 and 2021, have been replaced by a more insidious, but unrelenting succession of daily fatalities.

As an example, let’s take a figure for 21 December 2022 – 133 Covid-19 related deaths in England according to the UK government website – a number which may sound unremarkable compared to 2020 when people were being killed in their thousands by the virus (in the same week in the US 2,919 people died from Covid-19). But as Kucharski points out, over time even low levels of deaths can accumulate to a striking, perhaps even shocking number.

In the whole of 2022, the same database reveals that 46,099 people had perished from Covid-19 in England – the government are no longer recording this data for the whole UK. This is not quite the 75,240 deaths in 2020 or the 74,558 in 2021, but still more than most might expect. In contrast, over the course of a particularly bad influenza season, around 30,000 people in the UK might die from flu and pneumonia.

Yet within the corridors of Westminster and even newsrooms across the country, these ongoing deaths barely merit a mention compared to the myriad other crises on the agenda, from the cost of living to energy bills. And this is not just happening in the UK – across the globe, Covid-19 has been simmering away for months.

Scientists admit that it would likely take something drastic, such as the impact of a new supervariant, for this to change. Or, as Kucharski puts it, we have become so focused on the peak of the curve when it comes to Covid-related deaths, we have overlooked how this creeping toll of fatalities can still ultimately add up to a very significant number.

“We saw this with the Delta variant in 2021,” says Kucharski. “It wasn’t a very sharp peak but it was much, much longer and so the actual overall number of hospitalisations was quite similar to 2020. They were just distributed over a much longer period of time because the virus wasn’t sweeping through the population in the same way,” he says.

The same trend has been seen in the US, where some 2,000-3,000 Americans are still dying from Covid-19 every week. The Harvard University epidemiologist William Hanage says that he wrote to reporters at one large media organisation in July last year, informing them that if the ongoing weekly death toll was extrapolated to a full year, it would be equivalent to three particularly devastating flu seasons. But such news no longer automatically makes headlines.

“The numbers are actually really quite large,” says Hanage. “But one of the things that happens with humans is that things which are constant just become part of the everyday.”

Between January and November 2022, more than 248,000 Americans had died from the virus. You could be forgiven for wondering how we have all become so inured to these numbers, as if such a degree of mortality is now little more than mundane.

“We’ve come to really pay attention when there are very large spikes,” says Denis Nash, an epidemiologist at the City University of New York. “That has created the situation where people now are less likely to pay attention to what’s happening, unless there’s something big reflected in the data. But when you start to look at it over time, it really is scary how many deaths are still happening today.”

For Nash and others, one of the frustrations is that many of the fatalities feel highly preventable.

Booster hesitancy

Behind the endless graphs and visuals on government websites, it is surprisingly hard to drill down into the numbers to fully understand who is still dying from Covid-19. While epidemiologists had all kinds of demographic information to work with in 2020 and 2021, budget cuts have meant that it is now much more difficult to answer these kinds of questions, both in the UK and on the other side of the Atlantic.

For Nash, these cutbacks represent a grave public health error. “If you really did a good job of profiling who was being hospitalised or who is dying over the last, five or six months, you could get a sense of who’s falling through the cracks and why,” he says. “What we’re talking about is not even research, but a basic function of public health that is missing at the state, local and national level.”

Instead, the narrative of these deaths can only really be pieced together by speaking to the doctors on the frontline in hospitals. According to William Schaffner, professor of infectious diseases at Vanderbilt University Medical Centre in Nashville, Tennessee, they still tend to be those who were most vulnerable in the early days of the pandemic.

“The people we’re seeing hospitalised tend to be those who are either older, or younger people who are immune compromised, whether due to an illness or a medicine which suppresses their immune system,” says Schaffner. “It’s a lot of high risk groups.”

Andrew Ustianowski, a consultant at North Manchester General Hospital, paints a similar picture. “The deaths I could think that I’ve been involved in recently have been people that have been largely very immunosuppressed or very frail, and Covid therefore has a bigger impact,” he says. “It also doesn’t always mean that they died of Covid. They might have caught Covid in hospital, but it was actually their underlying disease that killed them.”

Many doctors feel that one of the ongoing problems which makes these individuals even more vulnerable is the sluggish uptake of booster vaccines, even in high-risk groups. While in the UK all over 50s and anyone younger with underlying health conditions qualify for a booster jab on the NHS this autumn – a total of 26 million eligible individuals – the latest statistics show that only half of those people have received their vaccines so far. Booster hesitancy is even more concerning in the US, with only 29.6% of Americans over 65 receiving their latest dose.

There are many reasons for this trend, from issues with vaccine access and vaccine hesitancy fostered by political tensions and misinformation, to “Covid apathy”, with both politicians and the general public keen to move on. In September, President Biden infamously declared that “the pandemic is over”, while public health messaging has become diluted by other emerging issues such as monkeypox, polio and hospitals straining under the burden of a two-year backlog of postponed operations. (Read more about monkeypox from BBC Future.)

But while missing a booster might have little impact on relatively healthy individuals who have mostly accumulated hybrid immunity from both past infections and vaccinations, evidence has repeatedly shown that vaccine-induced protection wanes rapidly in the most vulnerable. In March 2022, one study found that immunity drops markedly among elderly care home residents after just three months.

Scientists feel that governments and public health officials need to do more to ensure that the most at-risk are fully aware of the importance of ongoing jabs.

“I would argue that the ongoing cost of Covid should be less than we are tolerating,” says Hanage. “We could make it less, certainly in the United States, by vaccinating people better. Society, through a combination of political inattention and pandemic fatigue, has stumbled into the current situation. I know of people who died, unaware that they were eligible for boosters that would have likely saved their lives.”

Protecting the vulnerable

Because the ongoing impact of Covid-19 is even more disproportionally targeted towards the most vulnerable, questions are being asked as to whether society as a whole should do more to protect them, and find ways to mitigate the ongoing death toll.

Emma Hodcroft, an epidemiologist at the Institute for Social and Preventive Medicine at the University of Bern, points out that Switzerland has offered the latest round of booster vaccines to all over 18s, and suggests that this strategy could be applied more widely.

“Boosting younger age groups can make a difference by cutting transmission,” she says. “That could protect someone in one of those vulnerable groups from getting Covid and having a really bad outcome.”

While antivirals such as Paxlovid have been credited with reducing mortalities, their rollout hasn’t gone entirely smoothly. The UK purchased 4.98 million doses of antivirals at the end of 2021, but to date, only a small fraction have been used, while in the US, there have been questions as to whether Paxlovid has been appropriately targeted towards those who really need it.

“Doctors are sceptical as to whether every single person with Covid should be on an antiviral, which is understandable,” says Nash. “I think it should be just used in people who are much older – even if they’ve been vaccinated and boosted, they should be prioritised because of waning immunity. Or [it should be used in] the unvaccinated and people with co-morbidities.”

There are also fears that monoclonal antibodies – lab grown proteins which supplement the body’s immune system – such as Regeneron’s Regen-Cov and Astrazeneca’s antibody cocktail Evusheld, which have been credited with saving the lives of many people with compromised immune systems, are rapidly waning in effectiveness against newer variants.

As a result, Hanage says that while emerging variants such as BQ 1.1 – a subvariant of the Omicron variant – will likely have little impact at a population level, they will likely contribute to the steady ongoing death toll amongst the most vulnerable. “It seems pretty clear that monoclonal antibody therapies for people who need them are going to be less effective,” he says. “And what that means is that some of the most vulnerable people are going to be more likely to struggle with infection with the viruses that we’re going to see over this winter. But because they are a minority, I think that we unfortunately tend to discount them.”

Ongoing surveillance

In many ways the original inequities of the pandemic have only become larger the longer it has progressed. Scientists say that there are measures we can take to try and stem the insidious ongoing deaths from the virus, but these all require a degree of societal willingness to make sacrifices, from wearing masks on public transport to break transmission chains, or improving the ventilation of buildings.

“I think it is important to remember that while things are in a much better state than a couple of years ago, it isn’t equal for everyone,” says Hodcroft. “By taking steps like increasing ventilation to keep transmission down, the easier we make it for people who are at highest risk of continuing to die from Covid. But it can be complicated, because you have to convince whoever owns the building that this is worth doing.”

At a government level, decisions have to be made as to whether to invest large amounts of money in procuring newer versions of monoclonal antibodies which can protect a minority of citizens against the ongoing variants.

Schaffner told the BBC that on the Centres for Disease Control and Prevention’s latest conference call, it was revealed that the ineffectiveness of these antibodies is already becoming a serious problem in some parts of the US. But the bleak reality is that, once again, much of the dilemma comes down to a cost-benefit ratio. Around 3% of the US population have compromised immune systems and scientists have estimated that it will likely cost around $200m (£164m) to produce newer antibodies, run trials and get them authorised by regulators.

Epidemiologists warn that if we are too complacent about continuing to understand who is dying from the virus and why, we will likely be unprepared if the tide shifts. Monitoring Covid-19 has never been more complex – the sheer variation in population immunity, combined with a rapid succession of ever-evolving variants, has created a situation where it is almost impossible to predict when a new wave of cases will come. Equally, it’s becoming more difficult to identify if one variant is suddenly more virulent than those that have preceded it. This makes a degree of ongoing surveillance and data collection all the more important.

“With every few months, we are seeing that the amount of effort and money that’s going into this kind of data collection is going down,” says Hodcroft. “The question for me always is, how do we make sure that we’ve got enough data so that if there is a change, we’ll actually be able to see it? And make recommendations or warnings or whatever needs to be done.”

At the same time, doctors say that while any death is tragic, there has to be a degree of pragmatism when it comes to the impact of Covid-19. Ustianowski points out that many healthcare systems in the world ultimately have limited resources, and while the ongoing deaths from the virus are all entirely preventable if vaccines or antivirals had been administered in a timely manner, so are many deaths from heart disease or meningitis or other chronic illnesses.

“We do have interventions that can prevent people deteriorating,” he says. “Are we catching everybody we need to? No not by a long way. Is there still room for improvement with the interventions? Yes. But you’re never going to have a perfect situation, and that is the state of all areas in the health system. If we intervened at the age of 30 with people smoking, we’d have less lung cancer, and we’d have less heart disease later on. So there’s got to be a bit of realism in there as well.”