Like a line of dominoes, country after country has been shut down by the novel coronavirus. Despite signs the threat was making its way across the globe, there was a clear pattern of response in many parts of the world -- denial, fumbling and, eventually, lockdown.

In our globalised world, it's puzzling that so few lessons were learned in the early weeks of each country's outbreak, when the chances of containing and stopping the virus were highest. Now the focus is on flattening the curve, or slowing the virus' spread, to keep death tolls from climbing further.

As much of the world mulls gradually lifting lockdowns, there are still lessons to be learned from these four places that got it right. Here are 12 of those lessons.

Taiwan

Sitting just 180 kilometres (110 miles) off the coast of mainland China, Taiwan's outbreak could have been disastrous. At the end of January, the island was estimated to have had the second-highest number of cases in the world, according to Johns Hopkins University (JHU). 

But Taiwan, with a population of around 24 million people, has recorded just over 390 cases and six deaths, and yesterday, it reported no new cases at all. It's managed to do that without implementing severe restrictions, like lockdowns, or school and nursery closures.

In terms of its death toll, at least, Taiwan doesn't even have much of a curve to flatten, more of a line with a couple of rigid steps.

Compare that to the United States -- now the world's hardest-hit nation, at least in raw numbers -- which has reported at least 26,000 deaths. Even when you take population size into account, a level of success like Taiwan's could have meant just 83 deaths in the US.

Although Taiwan has high-quality universal health care, its success lies in its preparedness, speed, central command and rigorous contact tracing.

Lesson #1: Be prepared

Taiwan's preparedness came largely from some hard-learned lessons from the Severe Acute Respiratory Syndrome (SARS) outbreak in 2003, which killed 181 people on the island.

As a result, the island established a specialised Central Epidemic Command Centre, which could be activated to coordinate a response in the event of an outbreak. In a sign of how Taiwan wanted to get ahead of the coronavirus, the centre was activated on January 20, a day before the island even confirmed its first infection.

Because its authority was already established, the centre was able to implement stringent measures without being slowed down by lengthy political processes. It put more than 120 action items into place within three weeks, according to a list published by the Journal of the American Medical Association (JAMA). That list alone could serve as a manual on exactly what to do during an outbreak.

Lesson #2: Be quick

Taiwan's action came well before its first Covid-19 infection was confirmed on January 21. Three weeks before, within days of China's first reported case to the World Health Organisation (WHO), Taiwanese officials began boarding and inspecting passengers for fever and pneumonia symptoms on flights from Wuhan, the original epicentre of the virus in China. The island issued a travel alert for Wuhan on January 20, and two days later, still with just a single case, officials began updating the public in daily briefings.

A week after its first case, Taiwan began electronic monitoring of quarantined individuals via government-issued cell phones, and announced travel and entry restrictions, mostly targeting China's Hubei province, of which Wuhan is the capital. Just about every day after until the end of February, the government implemented new measures to keep the virus at bay.

Taiwan had only 329 cases when it imposed strict social distancing measures on April 1. In comparison, there were already 335 deaths and more than 3,000 cases on March 20, when Prime Minister Boris Johnson announced that pubs and restaurants were too close, and that most children would be pulled from schools and nurseries. And as the UK is not testing widely, the true number of infections is believed to be much higher than official figures show.

Lesson #3: Test, trace and quarantine

Authorities carried out widespread testing and tracing the contacts of infected people, putting them all under quarantine. It proactively tested anyone who got off cruise ships and even retested people diagnosed with influenza or pneumonia, to make sure they hadn't been misdiagnosed and were infected with coronavirus.

Lesson #4: Use data and tech

"A coordinated government response with full collaboration of its citizenry [was] combined with the use of big data and technology," associate professor of paediatrics at Stanford Medicine, Jason Wang, told CNN. Wang has also studied public health policy and co-authored the JAMA report on Taiwan's response.

Taiwan merged national health insurance data with customs and immigration databases to create real-time alerts to help identify vulnerable populations.

"Having a good health data system helps with monitoring the spread of the disease and allows for its early detection. When someone sees a physician for respiratory symptoms, the national health insurance database will have a record of it. It is easier to track clusters of outbreaks," Wang said.

Taiwan used mandatory online reporting and check-ins for 14 days after travel restrictions. It also employed "digital fencing" for close to 55,000 people in home quarantine, where alarms would sound if a quarantined person wandered too far from home. The technical surveillance methods used in Taiwan and by other governments have raised privacy concerns from civil society groups.

Iceland

Getting a coronavirus test in many countries can be near impossible, unless you're already very ill. Not so in Iceland, where anyone who wants a test gets one. Widespread testing has been crucial to the country's low number of infections and deaths, authorities there say. Only around 1,700 people have been infected in Iceland, and only eight have died.

Lesson #5: Be aggressive

Iceland's response to the coronavirus hasn't been particularly innovative. It's just been meticulous and quick. Like Taiwan, its speed has meant it hasn't had to be too restrictive -- people can still meet in groups of up to 20, if they stay two meters away from each other. While universities are closed, schools and nurseries are still open, allowing more parents to work.

"From the beginning, since we diagnosed our first case, we worked according to our plan. Our plan was to be aggressive in detecting and diagnosing individuals, putting them into isolation, and to be very aggressive in our contact tracing. We used the police force and the healthcare system to sit down and contact trace every newly diagnosed case," Iceland's chief epidemiologist Thorolfur Gudnason told CNN.

"We are finding that above 60% of new cases are in people already quarantined. So that showed that contact tracing and quarantining contacts was a good move for us," Gudnason said.

Lesson #6: Get the private sector involvedIn a public-private partnership between the National University Hospital of Iceland and biotech company deCODE Genetics, Iceland designed tests early and expects to have tested 10% of its population by the end of this week. It aims to test just about everyone and has already become a valuable laboratory for the world to learn more about the novel virus.Recent revelations that 50% of the people who tested positive in a lab in Iceland showed no symptoms at all, for example, has prompted other countries to take firmer action through social distancing, as they begin to realize preventing the virus' spread will be more challenging than initially thought.Kári Stefánsson, CEO and director of deCODE Geneticsm, told CNN that as of Monday, it had found 528 mutations of the coronavirus in mass testing in the community. These mutations could give insight to how lethal the virus becomes and offers important data to the world to better understand how it operates.

Lesson #7: Act preventatively

Icelandic Health Minister Svandís Svavarsdóttir has emphasized speed as a powerful tool, saying the approach is to stay "ahead of the curve." The country appears to have done just that. After just six imported cases were confirmed on March 3, Iceland immediately issued quarantine measures for all travelers returning from Italy, and increased travel restrictions in the following weeks.The National Police Commissioner declared a state of emergency on March 6, when the first two community-transmitted infections were confirmed. This sent a signal to government bodies to improve their preparedness, but it kept public gatherings as they were, only warning vulnerable people to stay away from crowded places.The country closed universities and junior colleges on March 13 and banned gatherings of more than 100 people on March 16, when it had just 61 confirmed cases and not a single death.Three days later, all Icelandic residents that entered the country were required to go into 14 days of quarantine, regardless of where they were traveling from.It wasn't until after all this action that, on March 24, Iceland's first death was reported. That same day, authorities banned gatherings of above 20 people and shut down public amenities, such as bars, swimming pools, museums and gyms.

Lesson #8: Use tech, but respect privacy

Like in Taiwan, Icelandic officials also made an app available for people to download to help chart the virus' spread. It creates a log of where the user has been. Users don't have to share that data with authorities -- but many do as it helps contact-tracing teams work out who may have been put at risk.In comparison, the UK's response has been slow. A government-supported app is only now in the works and is weeks away from launching. As it lags behind in testing, it is only just now looking into public-private partnerships.

South Korea

It's telling that South Korea reported its first coronavirus case at around the same time as the US and UK. South Korea is confirming around 30 new cases a day, while in the UK it's around 5,000, and the US it's more than 20,000.

The way each country tests varies, but their death rates among the population contrast just as dramatically. Fewer than one in every 100,000 people in South Korea's population have died from the virus, while in the UK it's around 18. It's almost eight in every 100,000 in the US, JHU data shows.

Lesson #9: You can drive-through test

South Korea's success has been largely down to its testing, according to Dr. Eom Joong Sik from the Gil Medical Center near Seoul. Eom is treating coronavirus patients in hospital and sits on a committee that advises the government in its response.

"Early diagnosis, early quarantine and early treatment are key," he told CNN.

"Since the first patient was confirmed, by installing more than 500 screening clinics all over the country, we sorted suspected cases and conducted tests, and we have worked hard to develop and maintain a system to conduct many tests with a small workforce over a short period of time," he said.

The country has also been innovative in how it tests. Eom's advisory team had hundreds of drive-through booths, just like at a McDonald's, set up across the country to offer tests that were largely free, quick and done by staff at a safe distance. The US has since replicated that model in some states.On March 16, the WHO called on governments of the world to "test, test, test." South Korea had already been doing that for weeks, and has to date tested more than 500,000 people, among the highest number in the world per capita.

Many countries are struggling to carry out thousands of tests each day. It's so difficult to get tested in the UK, for example, that people have been turning to mail-order kits, in an industry that hasn't yet been regulated by the government.

South Korea was also quick to move, implementing quarantining and screening measures for people arriving from Wuhan on January 3, more than two weeks before the country's first infection was even confirmed. Authorities rolled out a series of travel restrictions over the weeks after.

South Korea has also been rigorous in its contact tracing, though it was able to do that easily when it realised a large number of cases could be traced to one religious group in the city of Daegu, making contact tracing easier and giving authorities a specific area to carry out intensive testing.

"By carrying out tests on all members of the congregation and diagnosing even infected people without symptoms, the government carried out quarantine and treatment side by side," Eom said.

Once Daegu was established as the epicentre, authorities were ready with the ability and political will to test broadly, to trace contacts of people infected, and to quarantine them to try and contain the virus before it became a case of mitigating wide-scale death, as is now the case in much of Europe and the US.

Lesson #10: Learn from the past

South Korea was able to move quickly because, like Taiwan and many other Asian nations, it had been burned before. South Korea was mostly unaffected by the SARS outbreak, only reporting three cases and no deaths at all. But it was caught off guard by the Middle East Respiratory Syndrome in 2015, when it recorded 186 cases and 38 deaths, making it the worst-impacted country outside the Middle East.

So the political will needed to enforce measures during the coronavirus outbreak wasn't a problem and there was good coordination between the central government and the provinces.

It also helped that South Korea is one of the most technologically innovative countries in the world. Much of life there is already conducted online, so developing and enforcing the use of an app to monitor people in quarantine wasn't too difficult, though activists there too have warned of invasion of privacy.

Germany

Germany's case is a little different. The country hasn't really been able to keep infection numbers at bay much better than some of the hardest-hit nations. It currently has more than 132,000 confirmed infections, the fifth-highest in the world, JHU reports.

But Germany has been able to keep the death rate in its population relatively low. More than 3,400 people have died from the virus in Germany, around four people in every 100,000 across the country. That's well below Italy's 35 and the UK's 18.

Lesson #11: Test more as restrictions ease

Germany's success has also been its mass testing, but its well-resourced universal healthcare system has played a major role too, according to Martin Stürmer, a virologist who heads IMD Labor in Frankfurt, one of the labs conducting tests. Germany has also drawn in the private sector to make sure enough tests are carried out.

"From the beginning, Germany didn't stick to one or two or three central labs doing all the tests. Many private companies were involved, so we've been able to do 100,000 tests a day," Stürmer told CNN.

"There are some countries that have done it even better than Germany, in controlling infections, but what's quite important is broad testing, where we were able to see what was happening in our population. Only with mass testing can you identify people who might be infected."

Like Taiwan, South Korea and Iceland, Germany devised a test for the coronavirus and prepared a large number of kits early, well before the country even reported its first death.

As German Chancellor Angela Merkel announced Wednesday that the country would begin gradually scaling back its lockdown, the country is planning on carrying out even more tests, in case the increased contact leads to a second wave of infections. Like many countries, it will also test for antibodies to try and determine who among the community may be immune to the virus.

Germany's death toll has remained relatively low in part because the coronavirus trickled into the country mostly in young people. Many had been visiting Italy or Austria on ski trips.

Authorities were able to test people returning to Germany from these ski resorts and trace their contacts for testing too. Most of those people were young, and still today, the biggest age group by infections is 35-59, followed by 15-34. The virus is proving to be deadlier among the elderly around the world.

But as communal infections in the country grow, Stürmer fears that more elderly people could die in coming weeks and that the country's death rate will go up.

Germany recorded 315 deaths from complications related to Covid-19 in the past 24 hours, the country's centre for disease control, the Robert Koch Institute, wrote on its website on Thursday. This is the first time more than 300 deaths have been reported in a 24-hour span.

Lesson #12: Build capacity at hospitals

Germany ranks 18th in the world in terms of access to quality healthcare, according to an index published by The Lancet, sitting above the UK at 23rd and the US at 29th. But these indices only tell us so much. Italy, for example, ranks ninth and the country also carried out rigorous testing, yet it has recorded the second-highest number of deaths per capita in the world, after Spain.

In this situation, the difference appears to be the German healthcare system's huge capacity. Germany is projected to need about 12,000 beds at the peak of this outbreak in the middle of the month, according to projections from the Institute for Health Metrics and Evaluation. It has over 147,000, more than 10 times its need.

In contrast, the US has around 94,000 beds, some 15,000 beds short of its need. Germany has more spare beds in intensive care units that Italy has altogether.

In fact, Germany's health system has such a large capacity, its hospitals are now treating people for coronavirus from Italy, Spain and France.

Authorities have been able to get people with even moderate symptoms to hospital well before their conditions deteriorate, leading some experts to consider whether treating people early, getting them on ventilators before their condition worsens, for example, improves their chances for survival.

"Germany is not in a situation where the healthcare system is overloaded, like you see in Italy, where they need to decide whether to treat a patient or not. We don't have that," Stürmer said.

All data on case numbers and death tolls were taken from Johns Hopkins University on April 15 at 2a.m. ET.