The U.S. Centers for Disease Control and Prevention keeps a standing comparison. For each disease it takes the average number of cases a year in the 20th century, before vaccination, and sets it beside the number reported in the most recent year.
Drop in reported cases, 20th-century average vs. 2025
Smallpox29,005 a year → 0 in 2025
−100%
Diphtheria21,053 a year → 0 in 2025
−100%
Polio (paralytic)16,316 a year → 0 in 2025
−100%
Rubella47,745 a year → 0 in 2025
−100%
Measles530,217 a year → 1,975 in 2025
−>99%gt;99%
Mumps162,344 a year → 336 in 2025
−>99%gt;99%
Hib (under age 5)20,000 a year → 21 in 2025
−>99%gt;99%
Congenital rubella syndrome152 a year → 1 in 2025
−99%
Tetanus580 a year → 37 in 2025
−94%
Whooping cough (pertussis)200,752 a year → 28,132 in 2025
−86%
Whooping cough has fallen least, because protection from the current vaccine fades after some years; it is still down 86%.
← Swipe the table sideways to see every column →
Disease
Cases a year, 20th century
Reported cases, 2025
Decrease
Smallpox
29,005
0
100%
Diphtheria
21,053
0
100%
Polio (paralytic)
16,316
0
100%
Rubella
47,745
0
100%
Measles
530,217
1,975
more than 99%
Mumps
162,344
336
more than 99%
Hib (under age 5)
20,000
21
more than 99%
Congenital rubella syndrome
152
1
99%
Tetanus
580
37
94%
Whooping cough (pertussis)
200,752
28,132
86%
20th-century averages: Roush SW, Murphy TV et al., JAMA 2007;298(18):2155–2163. 2025 counts: CDC National Notifiable Diseases Surveillance System, provisional data through 27 Dec 2025. Hib figures are for children under five.
“But deaths were already falling”
The most widely shared anti-vaccine graph shows deaths from measles and other diseases falling for decades before the vaccines arrived, and concludes that vaccines did nothing. The first half is true. Better nursing, oxygen, intravenous fluids, antibiotics for secondary infections and better nutrition meant fewer children died of measles by the 1950s.
But they still caught it. Before 1963 nearly every child got measles, and hospitals still filled with the complications. Deaths measure how good medical care had become. Cases measure whether the disease was still spreading. Only the vaccines stopped the spread, which is why the case counts on this page collapse within a few years of each vaccine’s arrival.
Canada, 1924 to 2016: four diseases
Canada began counting reported cases of these diseases nationally in 1924. The charts below show every year of that record, as the number of reported cases for every 100,000 Canadians, so that a growing population does not distort the picture. The dashed green lines mark when each vaccine arrived. Hover over or tap any bar for that year’s count.
Reported cases are always fewer than real cases, because many mild illnesses never reached a doctor. That was especially true of measles before the vaccine, when nearly every child caught it.
Measles
Measles was not nationally reportable from 1959 to 1968, so those years are blank. National counts end in 2016; Canada reported 5,162 cases in 2025 and lost its measles elimination status that November.
BeforeFrom 1950 to 1958, Canada reported an average of 51,564 cases a year, about 349 for every 100,000 people.
AfterFrom 2000 to 2009, the average was 48 cases a year. After the 1989 outbreak, a second dose was added in 1996–97, and measles was eliminated in 1998.
Key dates
1935: Measles reached its highest recorded year, 83,127 reported cases.
1963: The first measles vaccine is licensed in Canada.
1989: A national outbreak of more than 21,000 cases.
2025: Canada loses its measles elimination status.
Polio
The national count for 1953 is 5,384 reported cases; other published histories give about 9,000 cases and nearly 500 deaths, counting differently. Canada was certified polio-free in 1994.
BeforeFrom 1950 to 1954, Canada reported an average of 2,545 cases a year. Summer epidemics closed swimming pools and filled hospital wards with children in iron lungs.
AfterFrom 1965 to 1969, the average was 2 cases a year. From 1996 to 2016, not one case was reported.
Key dates
1937: A major epidemic, centred in Ontario; 3,905 cases are reported nationally.
1953: Canada’s worst polio year.
April 1955: The Salk vaccine is declared safe and effective, and Canadian children are vaccinated with vaccine made at Connaught Laboratories in Toronto.
1962: Connaught licenses its oral polio vaccine.
Diphtheria
Diphtheria toxoid trials began in Ontario in October 1925; a Toronto study of 1926–29 found it cut cases by at least 90%.
BeforeIn 1924 Canada reported 9,057 cases, its highest ever. Diphtheria, “the strangler,” was among the leading killers of children.
AfterWithin ten years of the first toxoid programs, cases had fallen by three-quarters. From 1950 to 1954 the average was 241 a year, and from 1990 to 2016 Canada never reported more than ten in a year.
Key dates
October 1925: Toxoid trials begin in Brantford, Windsor and Hamilton.
1926–29: The Toronto school study.
1924–30s: Diphtheria deaths in the press.
Whooping cough
Whooping cough has not disappeared: protection from the vaccine fades over time. The rise in the 1990s followed the use of a whole-cell vaccine that proved less than 60% effective; a new acellular vaccine became available in 1997.
BeforeFrom 1934 to 1943, Canada reported an average of 17,909 cases a year, about 160 for every 100,000 people.
AfterThe vaccine came in 1943. In the 1970s the average was 2,224 a year, down 88%. It rose again to an average of 6,586 in the 1990s before falling.
Key dates
1934: The highest recorded year, 19,484 cases.
1943: Whooping cough vaccine introduced.
1990s: The resurgence, and the switch to the acellular vaccine.
CDC, “Vaccine-Preventable Disease Morbidity in the United States,” NCIRD Surveillance, updated 16 Mar 2026; slide “Comparison of 20th Century Annual Morbidity and Current Morbidity,” 25 Feb 2026.
Roush SW, Murphy TV, and the Vaccine-Preventable Disease Table Working Group, “Historical comparisons of morbidity and mortality for vaccine-preventable diseases in the United States,” JAMA 2007;298(18):2155–2163.
Public Health Agency of Canada, Canadian Notifiable Disease Surveillance System, annual counts and rates, 1924–2016 (open.canada.ca).
Public Health Agency of Canada, “CPHO Sunday Edition,” 2 May 2021 (polio history: 1955 Salk vaccine, 1962 oral vaccine, polio-free certification 1994).
Museum of Health Care at Kingston, “Diphtheria” (toxoid trials of October 1925; Toronto study 1926–29).
Pertussis vaccine history and the low-efficacy whole-cell vaccine: CMAJ 2006;174(4):451 (PMC1373746).
Measles in 2025: CIDRAP, “Canada loses measles elimination status after record year of outbreaks,” 10 Nov 2025.