The global toll in the Covid-19 pandemic was just shy of five million on Saturday (Oct 30), according to data from Johns Hopkins University, with the disease caused by the novel coronavirus taking just under two years to kill almost as many people as the population of New Zealand.

The worst may not yet be over. Experts have warned that with the winter months approaching, the world may witness another spike in cases and deaths as seen at the turn of the previous year.

Another danger is inequity in access to life-saving vaccines, with about half of the world still not inoculated. While some countries have already vaccinated the bulk of their populations and are contemplating booster doses, other nations' campaigns are flagging due to scarcity of vaccines.

This might mean that as some countries successfully manage the pandemic, others will continue to be devastated by fresh waves of infection.

The actual toll thus far is also subject to speculation.

"Both the reported number of cases and fatalities are grossly underestimated," Singapore's National Centre for Infectious Diseases executive director Leo Yee Sin told The Sunday Times.

"Countries with a more mature population having a higher proportion of elderly people understandably bear the brunt of having more fatal cases. These give challenges in generalising the impact of Sars-CoV-2 in differing settings," she said, referring to the virus that causes Covid-19.

Since the start of the pandemic, the world has witnessed an average of 7,711 deaths a day. But more than half of the total deaths, around 3.1 million, occurred in the Jan 1 to Oct 30 period this year, with an average of 10,329 deaths every day. In the days since July 1, the average number of deaths has been 8,656 a day.

Nevertheless, while total infections - currently over 246 million - continue to rise, the world is no longer fighting a completely unknown enemy, with vaccination programmes and improved treatment methods greatly reducing the threat posed by the disease.

However, it is unlikely that the world will be able to eradicate the virus in the near future.

"I think we are beginning to understand what it will mean to come to grips with the virus - which means living with it long term," Dr Stephen Kissler, a post-doctoral fellow at the Harvard TH Chan School of Public Health's Department of Immunology and Infectious Diseases, told The Sunday Times.

And deaths from Covid-19 based on officially reported data do not reflect the real casualty count, some experts say.

Said Prof Leo: "The loss of lives is not just from physical illness. Mental stress has become an increasingly prominent issue as the pandemic drags on.

"Two well-developed Asian countries - Japan and Singapore - saw a 13 to 16 per cent increase in the suicidal rate. Isolation, disadvantaged in the digital era, loss of income, fear of the disease have taken the greatest toll on the elderly."

A game changer

"The game changer in all of this is vaccination," said Dr Albert Ko, professor of epidemiology (microbial diseases) and medicine (infectious diseases) at Yale School of Public Health.

"In countries where large proportions of the population are vaccinated, the vaccines protect the population against the severe complications of Covid-19, which include hospitalisations and mortality," he said.

Data underlines the beneficial impact that vaccines have had in curbing the mortality rate, which is the percentage of deaths out of the total number of infections.

When outbreaks started emerging worldwide, the World Health Organisation (WHO) had estimated that the mortality rate would be 2 per cent. But in the subsequent months, it climbed as high as 7.3 per cent in May last year. At this point in time, the world had around 6.1 million Covid-19 infections.

But thanks to mass vaccination campaigns, the mortality rate has dipped to 2.02 per cent, in line with the WHO estimate, even as the infection tally has shot up to over 246 million.

This decline in the death rate despite a massive surge in cases was largely attributable to vaccines, according to experts.

But vaccines alone were not solely responsible for curbing mortality, said Dr Alex Richter, professor and honorary consultant in clinical immunology at the University of Birmingham.

"It is a combination of the vaccines and the treatment we now have," said Dr Richter, highlighting the use of drugs such as dexamethasone for people with severe manifestations of Covid-19.

Prof Leo added: "Whether death is preventable will be largely dependent on healthcare capacity and delivery, and importantly, the nation's ability to acquire, manufacture and deploy the life-saving therapeutics."

She said therapeutic agents including repurposed medication, novel agents such as monoclonal antibodies, as well as novel antiviral agents, will soon be made available.

Director Charles Gore of Medicines Patent Pool, a United Nations-backed public health organisation, said: "This is hopefully going to make things a lot easier in terms of keeping people out of hospital and stopping people dying in low- and middle-income countries."

Policy missteps

The experts were unambivalent about the role that policy missteps have played in the massive death toll, and the Covid-sceptic stance of some leaders like former US president Donald Trump and Brazilian President Jair Bolsonaro, though they did not attribute blame to anyone.

"If there's anything that we learnt during the pandemic, it is that probably the most important driver of success or failure during this pandemic is governance," said Dr Ko.

He highlighted the US experience in the most recent Delta wave in the country, where western states like California had very low rates of mortality, unlike southern states where the governors did not have strong messaging on vaccinations or face masks, with the result being much higher mortality rates.

"If all states in the United States had vaccination rates as we had in New England or Connecticut, we would have potentially saved 90,000 lives," he observed.

Said Dr Kissler: "The actions of world leaders clearly played a critical role in the management, or lack thereof, of the virus. Strong, science-based leadership in the pandemic could have averted many hospitalisations and deaths."

"Nevertheless, the correlation between good public health leadership and success in controlling the virus isn't totally straightforward," he added, citing the example of Germany, which suffered high rates of mortality relative to Singapore, Australia and New Zealand.

"Poor leadership clearly made the pandemic much worse than it needed to be, but even good leadership was not necessarily enough to keep the virus at bay, since our world is so interconnected and our societies are so varied," he said.

Still in crisis mode

Despite the slower rate of mortality, the world has yet to get the pandemic under control.

"Cases are still very high around the world and it may be that we're getting a natural dip in the Delta variant," said Dr Richter.

"But we've got winter coming and we don't know whether we're going to have any further variants, which could spike cases again. For much of the world, there is the real risk of waves because there is no natural immunity still in many populations."

Sharing the same view, Dr Kissler said: "I think that we haven't yet transitioned out of 'crisis' mode with this virus.

"There are still many parts of the world that will suffer major waves and strained healthcare systems, driven especially by the spread of the Delta variant. In time, though, I anticipate that Sars-CoV-2 will no longer dominate our daily decisions in the same way it has for the past two years."

The road ahead

There is an urgent need to step up global efforts to ensure that more people are vaccinated, especially in poor nations.

"We had never ever needed to vaccinate the whole world," said Dr Richter. "We should be acting morally. We just need more vaccines and we need better vaccine distribution because that potentially then leaves a legacy where we can vaccinate more rapidly all countries."

Dr Kissler expressed worry about parts of the world where vaccination rates remain low.

"Countries with excess vaccines must share them with other parts of the world and must build capacity for producing accessible vaccines in underprivileged parts of the globe," he said.

"If we are going to keep this virus at bay, we must do so as a global community."

Dr Ko reiterated the danger of inequitable vaccine access, as many countries that had vaccinated large segments of their population contemplated buying more vaccines for booster doses.

"We live in a highly interconnected world and so if we allow uncontrolled transmission in places in the world that don't have access to vaccination, you'll have replication and mutations," he said, warning that some permutations might evade the protection afforded by vaccines.

He criticised current bilateral vaccine-sharing efforts as inadequate, saying that nations need to strengthen multilateral efforts, such as the global vaccine effort Covax and that of the World Health Organisation.

"The big step up is scaling up (vaccine) production and distribution in making sure that no one is left behind in the world," said Dr Ko.

There is also a need for the world to reflect on the measures that have worked well so far, amid fears of more deadly waves in the winter, said Dr Richter.

"I think those measures are one, vaccination, and two, social distancing and reduction of movement, as well as measures that reduce aerial transmission and isolation."

Dr Kissler expects "a greater focus on public health going forward, with more attention paid to surveillance, early detection, and clear public health messaging".

On a more cautious note, he said: "Our next pandemic may look very different from this one, and there is a risk of leaning too heavily on the lessons learnt from this pandemic and not being attuned to the new demands faced by a potentially very different pathogen."

"Still, the most basic lessons will undoubtedly help us in the future: that we are intrinsically interconnected and that we bear a responsibility for one another's health," he added.