The History of Pandemics
Pan·dem·ic /panˈdemik/ (of a disease) prevalent over a whole country or the world.
As humans have spread across the world, so have infectious diseases. Even in this modern era, outbreaks are nearly constant, though not every outbreak reaches pandemic level as COVID-19 has.
Today’s visualization outlines some of history’s most deadly pandemics, from the Antonine Plague to the current COVID-19 event.
A Timeline of Historical Pandemics
Disease and illnesses have plagued humanity since the earliest days, our mortal flaw. However, it was not until the marked shift to agrarian communities that the scale and spread of these diseases increased dramatically.
Widespread trade created new opportunities for human and animal interactions that sped up such epidemics. Malaria, tuberculosis, leprosy, influenza, smallpox, and others first appeared during these early years.
The more civilized humans became – with larger cities, more exotic trade routes, and increased contact with different populations of people, animals, and ecosystems – the more likely pandemics would occur.
Here are some of the major pandemics that have occurred over time:
|Name||Time period||Type / Pre-human host||Death toll|
|Antonine Plague||165-180||Believed to be either smallpox or measles||5M|
|Japanese smallpox epidemic||735-737||Variola major virus||1M|
|Plague of Justinian||541-542||Yersinia pestis bacteria / Rats, fleas||30-50M|
|Black Death||1347-1351||Yersinia pestis bacteria / Rats, fleas||200M|
|New World Smallpox Outbreak||1520 – onwards||Variola major virus||56M|
|Great Plague of London||1665||Yersinia pestis bacteria / Rats, fleas||100,000|
|Italian plague||1629-1631||Yersinia pestis bacteria / Rats, fleas||1M|
|Cholera Pandemics 1-6||1817-1923||V. cholerae bacteria||1M+|
|Third Plague||1885||Yersinia pestis bacteria / Rats, fleas||12M (China and India)|
|Yellow Fever||Late 1800s||Virus / Mosquitoes||100,000-150,000 (U.S.)|
|Russian Flu||1889-1890||Believed to be H2N2 (avian origin)||1M|
|Spanish Flu||1918-1919||H1N1 virus / Pigs||40-50M|
|Asian Flu||1957-1958||H2N2 virus||1.1M|
|Hong Kong Flu||1968-1970||H3N2 virus||1M|
|HIV/AIDS||1981-present||Virus / Chimpanzees||25-35M|
|Swine Flu||2009-2010||H1N1 virus / Pigs||200,000|
|SARS||2002-2003||Coronavirus / Bats, Civets||770|
|Ebola||2014-2016||Ebolavirus / Wild animals||11,000|
|MERS||2015-Present||Coronavirus / Bats, camels||850|
|COVID-19||2019-Present||Coronavirus – Unknown (possibly pangolins)||2.7M (Johns Hopkins University estimate as of March 16, 2021)|
Despite the persistence of disease and pandemics throughout history, there’s one consistent trend over time – a gradual reduction in the death rate. Healthcare improvements and understanding the factors that incubate pandemics have been powerful tools in mitigating their impact.
November 8, 2021 Update: Due to popular request, we’ve also visualized how the death tolls of each pandemic stack up as a share of total estimated global populations at the time.
Wrath of the Gods
In many ancient societies, people believed that spirits and gods inflicted disease and destruction upon those that deserved their wrath. This unscientific perception often led to disastrous responses that resulted in the deaths of thousands, if not millions.
In the case of Justinian’s plague, the Byzantine historian Procopius of Caesarea traced the origins of the plague (the Yersinia pestis bacteria) to China and northeast India, via land and sea trade routes to Egypt where it entered the Byzantine Empire through Mediterranean ports.
Despite his apparent knowledge of the role geography and trade played in this spread, Procopius laid blame for the outbreak on the Emperor Justinian, declaring him to be either a devil, or invoking God’s punishment for his evil ways. Some historians found that this event could have dashed Emperor Justinian’s efforts to reunite the Western and Eastern remnants of the Roman Empire, and marked the beginning of the Dark Ages.
Luckily, humanity’s understanding of the causes of disease has improved, and this is resulting in a drastic improvement in the response to modern pandemics, albeit slow and incomplete.
The practice of quarantine began during the 14th century, in an effort to protect coastal cities from plague epidemics. Cautious port authorities required ships arriving in Venice from infected ports to sit at anchor for 40 days before landing — the origin of the word quarantine from the Italian “quaranta giorni”, or 40 days.
One of the first instances of relying on geography and statistical analysis was in mid-19th century London, during a cholera outbreak. In 1854, Dr. John Snow came to the conclusion that cholera was spreading via tainted water and decided to display neighborhood mortality data directly on a map. This method revealed a cluster of cases around a specific pump from which people were drawing their water from.
While the interactions created through trade and urban life play a pivotal role, it is also the virulent nature of particular diseases that indicate the trajectory of a pandemic.
Scientists use a basic measure to track the infectiousness of a disease called the reproduction number — also known as R0 or “R naught.” This number tells us how many susceptible people, on average, each sick person will in turn infect.
Measles tops the list, being the most contagious with a R0 range of 12-18. This means a single person can infect, on average, 12 to 18 people in an unvaccinated population.
While measles may be the most virulent, vaccination efforts and herd immunity can curb its spread. The more people are immune to a disease, the less likely it is to proliferate, making vaccinations critical to prevent the resurgence of known and treatable diseases.
It’s hard to calculate and forecast the true impact of COVID-19, as the outbreak is still ongoing and researchers are still learning about this new form of coronavirus.
Urbanization and the Spread of Disease
We arrive at where we began, with rising global connections and interactions as a driving force behind pandemics. From small hunting and gathering tribes to the metropolis, humanity’s reliance on one another has also sparked opportunities for disease to spread.
Urbanization in the developing world is bringing more and more rural residents into denser neighborhoods, while population increases are putting greater pressure on the environment. At the same time, passenger air traffic nearly doubled in the past decade. These macro trends are having a profound impact on the spread of infectious disease.
As organizations and governments around the world ask for citizens to practice social distancing to help reduce the rate of infection, the digital world is allowing people to maintain connections and commerce like never before.
Editor’s Note: The COVID-19 pandemic is in its early stages and it is obviously impossible to predict its future impact. This post and infographic are meant to provide historical context, and we will continue to update it as time goes on to maintain its accuracy.
Update (March 15, 2020): We’ve adjusted the death toll for COVID-19, and will continue to update on a regular basis.
Visualizing The Most Widespread Blood Types in Every Country
There are 8 common blood groups but 36 human blood types in total. Here we map the most widespread blood types in every country in the world.
The Most Widespread Blood Types, by Country
Blood is essential to the human body’s functioning. It dispenses crucial nutrients throughout the body, exchanges oxygen and carbon dioxide, and carries our immune system’s “militia” of white blood cells and antibodies to stave off infections.
But not all blood is the same. The antigens in one’s blood determine their blood type classification: There are eight common blood type groups, and with different combinations of antigens and classifications, 36 human blood type groups in total.
Using data sourced from Wikipedia, we can map the most widespread blood types across the globe.
Overall Distribution of Blood Types
Of the 7.9 billion people living in the world, spread across 195 countries and 7 continents, the most common blood type is O+, with over 39% of the world’s population falling under this classification. The rarest, meanwhile, is AB-, with only 0.40% of the population having this particular blood type.
Breaking it down to the national level, these statistics begin to change. Since different genetic factors play a part in determining an individual’s blood type, every country and region tells a different story about its people.
Regional Distribution of Blood Types
Even though O+ remains the most common blood type here, blood type B is relatively common too. Nearly 20% of China’s population has this blood type, and it is also fairly common in India and other Central Asian countries.
Comparatively, in some West Asian countries like Armenia and Azerbaijan, the population with blood type A+ outweighs any others.
The O blood type is the most common globally and is carried by nearly 70% of South Americans. It is also the most common blood type in Canada and the United States.
Here is a breakdown of the most common blood types in the U.S. by race:
O+ is a strong blood group classification among African countries. Countries like Ghana, Libya, Congo and Egypt, have more individuals with O- blood types than AB+.
The A blood group is common in Europe. Nearly 40% of Denmark, Norway, Austria, and Ukraine have this blood type.
O+ and A+ are dominant blood types in the Oceanic countries, with only Fiji having a substantial B+ blood type population.
More than 41% of the population displays the O+ blood group type, with Lebanon being the only country with a strong O- and A- blood type population.
Nearly half of people in Caribbean countries have the blood type O+, though Jamaica has B+ as the most common blood type group.
Here is the classification of the blood types by every region in the world:
Unity in Diversity
Even though ethnicity and genetics play a vital role in determining a person’s blood type, we can see many different blood types distributed worldwide.
Blood provides an ideal opportunity for the study of human variation without cultural prejudice. It can be easily classified for many different genetically inherited blood typing systems.
Our individuality is a factor that helps determine our life, choices, and personalities. But at the end of the day, commonalities like blood are what bring us together.
Pandemic Recovery: Have North American Downtowns Bounced Back?
All North American downtowns are facing a sluggish recovery, but some are still seeing more than 80% less foot traffic than pre-pandemic times
Pandemic Recovery: Have Downtowns Bounced Back?
As we continue on our journey towards recovery from the impacts of the pandemic, North American offices that sat empty for months have started to welcome back in-person workers.
This small step towards normalcy has sparked questions around the future of office life—will office culture eventually bounce back to pre-pandemic levels, or is remote work here to stay?
It’s impossible to predict the future, but one way to gauge the current state of office life is by looking at foot traffic across city centers in North America. This graphic measures just that, using data from Avison Young.
Change in Downtown Office Traffic
According to the data, which measures foot traffic in major office buildings in 23 different metropolitan hubs across North America, remains drastically below pre-pandemic levels.
Across all major cities included in the index, average weekday visitor volume has fallen by 73.7% since the early months of 2020. Here’s a look at each individual city’s change in foot traffic, from March 2, 2020 to Oct 11, 2021:
|City||Country||Change in Foot Traffic|
|San Francisco Peninsula||🇺🇸||-70.00%|
The Canadian city of Calgary is a somewhat unique case. On one hand, foot traffic has bounced back stronger than many other downtowns across North America. On the other hand, the city has one of the highest commercial vacancy rates in North America, and there are existential questions about what comes next for the city.
Interestingly, a number of cities with a high proportion of tech jobs, such as Austin, Boston, and San Francisco bounced back the strongest post-pandemic. Of course, there is one noteworthy exception to that rule.
A Tale of Two Cities
Silicon Valley has experienced one of the most significant drops in foot traffic, at -82.6%. Tech as an industry has seen one of the largest increases in remote work, as Bay Area workers look to escape high commuter traffic and high living expenses. A recent survey found that 53% of tech workers in the region said they are considering moving, with housing costs being the primary reason most respondents cited.
Meanwhile, in a very different part of North America, another city is experienced a sluggish rebound in foot traffic, but for very different reasons. Ottawa, Canada’s capital, is facing empty streets and struggling small businesses that rely on the droves of government workers that used to commute to downtown offices. Unlike Silicon Valley, where tech workers are taking advantage of flexible work options, many federal workers in Ottawa are still working from home without a clear plan on returning to the workplace.
It’s also worth noting that these two cities are home to a lot of single-occupant office buildings, which is a focus of this data set.
Some Businesses Remain Hopeful
Despite a slow return to office life, some employers are snapping up commercial office space in preparation for a potential mass return to the office.
Back in March 2021, Google announced it was planning to spend over $7 billion on U.S. office space and data centers. The tech giant held true to its promise—in September, Google purchased a Manhattan commercial building for $2.1 billion.
Other tech companies like Alphabet and Facebook have also been growing their office spaces throughout the pandemic. In August 2021, Amazon leased new office space in six major U.S. cities, and in September 2020, Facebook bought a 400,000 square foot complex in Bellevue, Washington.
Will More Employees Return or Stay Remote?
It’s important to note that we’re still in the midst of pandemic recovery, which means the jury’s still out on what our post-pandemic world will look like.
Will different cities and industries eventually recover in different ways, or are we approaching the realities of “new normal” foot traffic in North American city centers?
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