It has taken just nine months for Covid-19 to claim a million lives, a milestone it may cross tomorrow.

Given that 95 per cent of these casualties occurred over the past six months, will the next million deaths come even sooner? Or will the world find a solution to stem the pandemic?

No one has the answer, but those one million deaths provide some valuable pointers.

More than 200,000 of them were in the United States which, with 4 per cent of the world's population, accounts for over 20 per cent of Covid-19 deaths.

Just four countries - the US, Brazil, India and Mexico - account for more than half of the Covid-19 deaths globally. The other 480,000 deaths are spread over about 190 other countries and territories.

The major factors that contribute to Covid-19 deaths are: Age: Older people who are infected have a higher risk of dying. A comparison done by the US Centres for Disease Control and Prevention (CDC), using 18 to 29 years as the base group found that toddlers four years and younger are nine times less likely to die, while deaths are 630 times more likely in seniors aged 85 years and older.

Underlying medical conditions: The CDC said regardless of age, certain medical conditions also put people at higher risk of death. They include cancer, chronic kidney disease and heart conditions. Transplant recipients are also more susceptible as they have weakened immune systems.

Overwhelmed healthcare systems: More people die when healthcare systems are stretched beyond capacity, as some patients are not able to get the care they need to overcome the disease. Infection numbers: This may be obvious, but it bears repeating. Only those who get infected by the coronavirus are at risk of dying from it.

How countries have performed in their battle against the virus has depended largely on how they have managed these four factors.

Countries that have been successful in keeping infection numbers low have also seen fewer deaths. They include:

• New Zealand (25 deaths out of 1,827 infected in a population of five million)

• Vietnam (35 deaths out of 1,069 infected in a population of 97.5 million) and

• Thailand (59 deaths out of 3,516 infected in a population of 70 million).

Countries where healthcare systems were overwhelmed for some time also recorded higher mortality numbers. These include several European countries like:

• Britain (41,902 deaths out of 416,363 infected in a population of 68 million)

• Italy (35,781 deaths out of 304,323 infected in a population of 60 million) and

• France (31,511 deaths out of 497,237 infected in a population of 65 million).

In April, there were reports from these countries of patients being turned away for lack of beds, doctors crying as they could not provide intensive care to patients who needed it, and overworked healthcare professionals clocking very long hours.

Infections among the sick and elderly are one reason for the high number of deaths in the US. Reports by US media say care facility deaths account for at least a quarter, and perhaps as much as a third, of Covid-19 deaths in the country.

The virus has spread globally with practically no country spared. So why have some succeeded and others failed so miserably in dealing with this virus?

Often with a novel virus, the countries that are first to face it fare the worst, since it would have caught them by surprise. Also, little is known of the new bug. But not with this pandemic.

China, where this new virus emerged, has done relatively well with 4,745 deaths out of 90,934 infected in a population of 1.4 billion. In fact, as the epicentre moved from Asia to Europe and then to the Americas, the problem seemed to get worse.

Dr Michael Ryan, executive director of the World Health Organisation's (WHO) Health Emergencies Programme, gave some possible answers during the NUS Medicine's Covid-19 webinar on Sept 10.

He suggested that the disparate performances of different countries stemmed from insufficient preparation, lack of muscle memory and varying levels of social cohesion.

Not prepared

Dr Ryan, who has been at the forefront of managing acute risks to global health for nearly 25 years, said the world has learnt a lot from past health emergencies, "but we haven't implemented a lot of those learnings".

He said globally, there has been "serious under-investment in managing and mitigating" the risks from new infectious diseases.

It is not that countries have not invested in healthcare. But the investments tend to be in bricks-and-mortar infrastructure - more hospitals and beds, and more laboratory facilities. He said this is "very static preparedness", adding that "the true essence is the way data is collected and decisions are made". It was this lack of preparedness in Europe that resulted in the surge in cases and hospitals being overwhelmed.

"Much of the failure on the global level is the failure to prepare, not in failure to perform," said Dr Ryan. "I honestly think everyone had tried to do their best. Unfortunately our best is sometimes not enough."

Citing the example of running a marathon, he said: "No matter what my will is, no matter what my intent, I will not finish that marathon because I have not prepared. Good will and best intentions aside, performance is always dependent on your preparation."

Muscle memory

Only countries that have been through a health emergency - such as Sars (severe acute respiratory syndrome) for Singapore which killed 33 people out of 238 infected in 2003 and caused the closure of Tan Tock Seng Hospital, one of the busiest hospitals here - would have muscle memory ingrained in their psyche. Such countries would be quick to collect, analyse and act on data. They also possess the capacity to make decisions, to create new science and turn that into policy and action.

Dr Ryan said "Asian countries have a much higher sense of alert for this kind of virus. (It) triggers a collective community disquiet".

In the first week of January, when the world heard of the possibility of a novel virus, the number of phone calls he received from Asian countries like Singapore, South Korea and Japan had "gone through the roof". These countries had an immediate level of concern.

Singapore, for example, had set up the multi-ministry task force before a single patient here had been diagnosed with Covid-19.

For the rest of the world, Dr Ryan said, "it's a remote concept", resulting in them being "caught off guard" when the virus hit them.

Social cohesion

Countries that have performed better also tend to have stronger community buy-in, said Dr Ryan.

He said such a health emergency "triggers a collective community disquiet and governments are expected to be ready to handle it". People see government intervention as responsible action.

But in some countries, that is seen as interference in the lives of individuals and an invasion of personal privacy. It boils down to differences in social contract that people have with their government.

He said countries where people see themselves as part of a community tend to absorb information positively and act in a more sustainable manner.

But in societies where the individual is seen as the most important unit of society, as opposed to the community, people do not feel that sense of responsibility.

He said: "Their response is: What does it mean to me? What is the transmission risk for me? Will the vaccine work for me? Is my travel important for me? Rather than ask the question: Is my travel behaviour dangerous to someone else? Is my attending the event dangerous for someone else? Is my taking the vaccine important to society?"

He said: "Societies with a high level of social cohesion and sense as a group have done better."

Dr Ryan added that if one takes the view that social distancing, avoiding crowds and hand hygiene can slow the spread of the virus, "then your success is almost 100 per cent based on society's willingness to accept those rules".

Political leadership

What does politics have to do with the science and strategy of fighting the virus that has disrupted lives and livelihoods globally?

More than one would think, especially in the US and Brazil - two of the three countries worst hit by the virus. In both cases, the leaders were driving their own agenda to keep the economy open.

With his re-election campaign on the line, US President Donald Trump has ignored the advice of health authorities and downplayed the severity of the Covid-19 crisis. He even took the CDC, one of the foremost health authorities in the world, out of the reporting line.

Brazilian President Jair Bolsonaro even replaced his Health Minister with one willing to push for reopening the economy.

Professor Teo Yik Ying, dean of the NUS Saw Swee Hock School of Public Health, cautioned it may be premature to determine the part that politics has played "in the appalling situations in US and Brazil".

But he added: "When leaders of countries choose to ignore the facts and the science of Covid-19, this is when poor decisions are made that amplify the spread of the coronavirus in a country, rather than help to improve the situation."

The lessons of the past nine months are clear. Reactions to the unfolding crisis will have to be faster. Policy will have to be driven by science rather than political agendas.

And while the search for a vaccine continues, population buy-in for Covid-19 measures will determine whether the virus claims another million lives - and if so, how quickly - or if it will be kept at bay.