It is by no stretch of the imagination to say that the world would be completely different if it were not for science. But, like, how exactly? The goal of this series is to use numbers to showcase what our lives would be like without scientific advances. Part 1 looks at the scourge of humanity across millennia: contagious disease.

Getting personal with disease

Stomach heaving because my lungs felt incapable, I walked into my parents room in the middle of the night seeking refuge. I had pneumonia yet again. Pneumonia became the herald of winter for a dozen years of my childhood. Each breath was a struggle. Each breath felt like I was taking in less oxygen than the breath before it, like I was slowly depleting my reserves until I’d be empty. It’s hard to describe the magical relief from a single puff of an inhaler, like breathing instantly became the most amazing thing in the world. Just breathing. If you haven’t had pneumonia then perhaps you’ve had a similar experience of one moment feeling terribly sick and the next fantastically normal. Even though my experience was tame compared to what has certainly plagued other families, it made me appreciate advances in modern medicine.

Lower respiratory infections (LRIs), including pneumonia, are the leading cause of death from infectious diseases in the U.S. and worldwide, attributed to 92 thousand and 2.7 million deaths in 2015, respectively. This is a huge improvement from the 3.4 million LRI deaths worldwide in 1990, especially considering our population also increased from 5.3 to 7.3 billion people over those 25 years.

Millions of lives are saved every year through the fruits of scientific endeavors. This “ghost generation” wouldn’t exist without advances in medicine and public health policy. How many brothers and sisters, children and parents, friends and loved ones have been blessed with being able to live out their lives because they were spared from disease?

This analysis applied the mortality rates of contagious diseases in 1990 to every year through 2015 to determine that advances in medicine and public health have saved 107 million lives over those 25 years. This methodology is explained more fully below, but first, a historical perspective on how we got to this idea of lives saved through science.

A refusal to believe in cholera

Prior to the development of vaccines and antibiotics, a great many scientists contributed to our understanding of how diseases work. Their ideas ranged from “maybe we shouldn’t be dumping our buckets of shit into the streets” to proving that many diseases come from microorganisms instead of “bad air” as many previously thought. These were novel concepts at the time. So much so that public health officials in London wouldn’t accept the possibility that fecal contamination of the water supply caused a cholera outbreak in 1853 and 1854— the third pandemic globally — resulting in over 10 thousand deaths in England. They stuck to the “bad air” theory.

It seems impossible today that developed nations of the time would reject an idea that could save so many lives. Two more cholera pandemics took place in the 1860s and the 1880s. Estimations of cholera deaths are difficult to find, but taken at a global scale, it seems clear that the order of magnitude was hundreds of thousands of deaths for each of those pandemics. What would have happened if public officials had taken a more critical examination of their own beliefs and biases when presented with new information? Actually, we know what happens when science prevails because there was a sixth cholera pandemic. It hit hard in India, Russia and The Philippines at the turn of the 20th century, but less so in western Europe because of efforts to finally improve water sanitation thanks to an ever-growing body of knowledge about how disease really works.

Cholera continues to destroy families in impoverished areas, especially following tropical storms when water contamination is more common. What has changed is a public acceptance of how cholera is caused, how to treat it, and how to distribute that treatment. Even though the median cost of oral rehydration salts is about $0.10 per packet (for one liter of water) and alone they are 90% effective, there are still between 21 and 143 thousand cholera-related deaths annually. The rest of this analysis will group cholera deaths under diarrheal diseases.

The eradication of smallpox

More than any other disease, smallpox has shaped the course of history. The Egyptian Empire is thought to have the first recorded signs of smallpox over 3,000 years ago. The Roman Empire was greatly weakened by the disease around 166 AD, making them more susceptible to barbarian raids and their eventual downfall. European colonials brought the disease to the Americas, where smallpox killed nine times more people than military actions did. The disease is incredibly lethal, and those who survived were often left blind, with scars from the pustular bumps across their faces and bodies.

Over 150 years after the smallpox vaccine was discovered, the disease was still running rampant around the world. In the 1950's, approximately 50 million people contracted smallpox worldwide, and about 15 million (or 30%) of those people died. Annually. The World Health Organization was created in part to eradicate smallpox, and by 1980 the WHO declared that there were zero cases of smallpox in the world. It was truly an incredible act of scientists, politicians, and clinicians coming together to achieve something beneficial for all of humanity. Not all diseases are as straightforward to prevent as smallpox, which is why the WHO continues on it’s mission to help people live longer, healthier lives.

Less disease, longer lifespans

Life expectancy has increased dramatically in the past century. This is mostly due to a lower infant mortality rate. When looking at life expectancy for children already 10 years old, we see almost a 20 year increase from 1900–2000.

Pneumonia, tuberculosis and diarrhea were the leading causes of death in 1900 in the United States. Public health efforts were spearheaded with sanitation and hygiene improvements. Animal and pest control along with vaccines and antibiotics helped contribute to the 16-fold decrease in mortality rate from infectious diseases during the century (approximately 800 to 50 per 100k population).

What would the world look like if there were no improvements to public health for the past 100 years?

Probably pretty bad, but that’s also a pretty extreme hypothetical. The lovely folks at Our World In Data put these maps together to showcase how life expectancy has improved.

A question worth investigating

How about this: What if governments decided in 1990 that many of the deadliest diseases have already been taken care of, so they decided to defund research in epidemiology, microbiology and related fields in order to reduce taxes? What would the world look like if it stuck to the 1990 levels of public health?

Now we’re talking! We have solid data on disease incidence and mortality rate for all countries since 1990, compiled with more effort than you and I can probably appreciate by over 1,800 collaborators from nearly 130 countries. The Institute for Health Metrics and Evaluation (IHME) at the University of Washington has coordinated the Global Burden of Disease(GBD) studies and maintains the data free to download and segment any way you wish.

Using the mortality rate from 1990, we can estimate how many people would have died in 2015 had there been no advances to public health, and compare this to the actual deaths in 2015. The difference between these numbers can be considered how many lives science has saved — the ROI of science, if you will. We can be a little more precise and calculate this difference for every year and add the results. This method is very similar to what Christopher Murray, Director of the IHME, and Ray Chambers, Special Envoy for Health of the United Nations, used in their Lives Saved Scorecard. The difference is their comparison used the prior year’s value for each iteration, while this method is fixated on each country’s 1990 value for each iteration. In both cases the results are estimates because we can’t really measure something that didn’t happen, and in both cases the methodology answers a different question. Our question is how many people owe their lives to better public health efforts over 25 years.

The ROI of science: 107 million lives saved

Globally, over 107.4 million lives were saved over 25 years due to advances in medicine and public health policy related to infectious diseases.

“Public health policy” is meant to be a broad term. It means to encompass everything from improved access to clean water, better sanitation, pest control, improved nutrition, reduced poverty, and increased vaccination & public outreach campaigns.

Perhaps in accordance with this, there is not a similar trend for non-communicable diseases like cancer. The global mortality rate from these types of diseases is higher for almost every year past 1990. Using the same methodology we get a difference of 19.8 million “extra” deaths. On a morbid note, everyone dies. When less people die from infectious diseases there are more dying due to other causes. However, the net difference is still 87.6 million lives saved, suggesting more people are living longer, healthier lives.

Which diseases have we made the most progress with? And in which countries? Let’s dig in.

The calculation for the number of lives saved does not include HIV/AIDS because the disease was not very widespread in 1990. The global HIV/AIDS mortality rate was highest in 2004, at 27.5 per 100 thousand people, down to 16.3 per 100 thousand people in 2015. If we factor it back in starting at 2004 then the number of lives saved goes up to over 111 million. This marks a 41% decrease in mortality over 11 years, or over 4 million lives saved. Subsequent graphs and figures will be applying the 2004 HIV/AIDS mortality rate.

Most of the lives saved over these 25 years come from developing nations. India ranks the highest with over 39 million lives saved, and China in second, with over 14 million lives saved. Much effort has been taken to lift people out of extreme poverty in these two countries (living at less than $1.90/day USD). This means greater access to clean water and better sanitation, which are major reasons for the large number of lives saved from infectious diseases. An estimated 200 million people were lifted out of extreme poverty worldwide between 2012 and 2015.

Visit the interactive version (screenshot below) to see the total lives saved breakdown for the top 10 countries.

Not all countries have decreased their mortality rates from infectious diseases over the 25 years. This methodology indicates that Japan has had nearly 1 million more people die from infectious diseases than predicted using their rates from 1990. Japan has made progress with tuberculosis and hepatitis, but their mortality rate from lower respiratory infections has more than doubled, from 57 deaths per 100k population in 1990 to 123 deaths per 100k population in 2015. This is likely attributable to the reduced birth rate and increased population age 65 and older, rather than a decline in Japan’s Ministry of Health, Labor and Welfare.

How does your country compare? Visit the interactive version, as shown below, to find out (best viewed on desktop).

Reducing incidence and death from contagious diseases are only part of the picture when considering quality of life. As the IHME noted in their most recent publication, these reductions have been offset by war, obesity and substance abuse. Some congratulations are in order for our accomplishments, but our work is far from over.

Closing remarks

The idea of organisms invisible to the eye being the agents of disease surely sounded laughable when first proposed. Thankfully, those in power eventually listened to reason and we all have benefited from a higher quality of life. There will be countless more laughable ideas as we venture forward, however we owe it to ourselves and future generations to hold our beliefs in check as we evaluate new evidence.

This article was not written in collaboration with the IHME at the University of Washington, nor was it sponsored by any other entity. The GBD Results Tool where this data came from was sponsored by the Bill and Melinda Gates Foundation.

Feel free to share any of the images or interactives from this article as long as you give proper attribution and a link to this source.

Appendix

Astute readers may have noticed that the total lives saved from the top 10 countries was about 97.1 million, or 87% of the global lives saved. While the majority of lives saved did come from a small group of countries, this would be an overestimation of their impact. The sum of lives saved using all 195 countries was over 142 million, which would make the top 10 countries account for around 68% of the global lives saved. The discrepancy is due to slightly differing mortality rates in this analysis than the IHME, which is a result of using different population data. This analysis used population data by country from the U.S. Census Bureau and global population via Our World in Data (had a closer match to IHME global rates than with Census Bureau sum of countries). The mortality rates in this analysis are squarely within the lower and upper limits from the IHME data, suggesting they are perfectly reasonable estimates. Even minor differences become noticeable when they are compounded for every country across every year. The true number of lives saved cannot be directly measured, so a conservative approach would use the lesser of the two values for global lives saved.

The following is an excerpt from the appendix of the publication “Keeping score: fostering accountability for children’s lives” cited as a comparable methodology in this article.

Estimating the number of child deaths averted through interventions

Empirical assessments of levels of child deaths observed in each country and year are available and updated annually. Simple comparison of the number of child deaths in a year compared to the number of deaths observed in the year prior provides an estimate of the additional child lives saved. This comparison can take into account changes in the size of the birth cohort by comparing observed deaths in a country‐year with those expected on the basis of death rates observed one year prior applied to the current population. It is unlikely that all of the change in child deaths is due to health interventions; some are likely due to changes in risk factors such as indoor air pollution, access to water and sanitation, changes in maternal or child nutritional status, and more generally due to changes in socioeconomic status. To avoid overestimation of the number of child deaths averted through health intervention, we take advantage of the analysis published by Wang et al, which examined the component of changes in child mortality that can be linked to changes in income per capita and educational attainment. Based on the econometric model used by Wang et al, we estimate counterfactual deaths in a scenario where income, education, and number of live births change with time but everything else is set at its year 2000 value. HIV/AIDS is an exception here, where we use the crude death rates due to HIV/AIDS assuming there is no intervention. We then get the difference between counterfactual deaths and the estimated numbers of death by Wang et al. The year‐to‐year change in the aforementioned difference in deaths is used as an approximation for the changes in under‐five deaths attributable to child health interventions.