Was it sanitation or vaccination?

In 2025, the “sanitation, not vaccines” trope spread widely. It claims that clean water, nutrition, and hygiene — not vaccines — are what reduced deadly diseases. It spread because well-known public figures and podcasts talked about these ideas in simple ways that were easy to clip, share, and spread across social media like Twitter and YouTube.

Clean water, safe sewage systems, and good nutrition save millions of lives. They are especially important for diseases spread through food and water, like diarrhea, which still kills over 500,000 children under age five each year worldwide.

Sanitation helped make people less likely to die once they were sick. Better food, cleaner hospitals, and improved care meant stronger bodies and better recovery. But many dangerous diseases spread through the air, not through dirty water. For these diseases, sanitation does very little to stop infection.

This is where many charts are confusing. They often show death rates, not how many people actually got sick. Deaths went down over time because care improved, even while large numbers of people were still being infected. Before vaccines, nearly every child got measles, polio caused tens of thousands of cases each year in the U.S., and smallpox kept causing outbreaks around the world.

When vaccines were introduced, case numbers dropped sharply, not just deaths. Looking only at death charts hides this difference and makes it seem like vaccines were not needed, when they were actually the turning point.

Measles is one of the most contagious diseases ever known. It spreads through the air and can stay in a room for up to two hours after a sick person has left. If one person has measles, an unvaccinated person has a 90% chance of getting sick.

Before the measles vaccine in 1964:

• Nearly all children got measles by age 15
• 500–600 children died each year in the United States

Two doses of the MMR vaccine prevent about 98% of measles cases. Vaccination has prevented tens of millions of deaths worldwide. Good nutrition and vitamin A can help someone recover, but they do not stop measles from spreading.

Polio is caused by a virus, not chemicals like DDT. Scientists have isolated the poliovirus many times and shown that it causes paralysis.

Before vaccines:

• The U.S. had about 57,000 polio cases in 1952
• Over 21,000 of those cases caused paralysis

Polio spreads through tiny amounts of fecal matter (poop), often without anyone knowing. Before modern sanitation, most children were exposed to polio as babies, when they were protected by antibodies from their mothers. They usually had mild illness and became immune.

When sanitation improved in the early 1900s, children were exposed later in life, after that protection was gone. This led to larger and more severe outbreaks, even though overall health improved. Sanitation changed who got polio, but it did not stop the virus. Vaccination did.

We still vaccinate for polio today because the virus still exists in parts of the world and can return through travel, as shown by the U.S. polio case in 2022.

Smallpox spread through the air, not dirty water. Even as sanitation improved, smallpox continued to cause deadly outbreaks for centuries. Smallpox was eradicated through a global vaccination campaign. Since eradication in 1980, there have been zero natural cases anywhere in the world. No sanitation effort has ever achieved this for an airborne disease.