A graph a day: 30th April 2025
The US is at a tipping point for the return of measles and possibly other vaccine-preventable diseases. Other countries might follow if the vaccination levels drop below the herd immunity threshold.
Measles and vaccination are such broad subjects, and well covered in the new book, How vaccines work, as well as in many other publications, like one of my favourites, Vaccine Nation published over a decade ago.
The measles vaccination campaign is indeed one of the success stories of modern medicine and public health. The population health had been improving since the end of the 19th Century, leading to the decline in the rate of death due to measles. By the 1940s, with the advent of novel treatments and eventually antibiotics, the probability of death due to measles became about 0.01%.
However, the number of cases was steady throughout this time until the government, concerned about the health of the nation, started a massive vaccination campaign in the early 1960s.
Given that the population was already close to herd immunity, due to the immunity caused by past infections, the campaign brought a spectacularly fast decline in the number of cases, followed by a drop in the number of deaths.
A similar picture emerged in the UK (my graph based on the UK government data). The number of deaths went down remarkably, even before the vaccination was introduced in 1967. The number of cases declined very quickly in 1970s, but it was the introduction of the second dose recommendation that brought it almost to zero by 1990.
The UK measles mortality rate (deaths per case) was going down in the 1940s and 1950s, but it stabilised in the late 1950s at about 0.02% – showing the limits to what doctors can do to save a difficult measles case and complications following the infection. Note the logarithmic scale on the graph above.
Why has the death rate gone up in the late 1990s? Firstly, we need to be very careful with the interpretation of the results, as the number of deaths is very low (1-5 per year). Most of the deaths since 2000 are either for adults (late effects of measles) or immuno-compromised children.
It is these deaths in the vulnerable population that are particularly concerning once the measles vaccination levels go below the herd immunity threshold. The resulting wave will particularly hit those whose immunity is compromised.
How does risk compare for vaccination and for measles disease?
The graph from How effective and safe are measles vaccines? at OurWorldinData.org, and retrieved from: [Online Resource], is based on the “gold-standard” in literature reviews.
It is not to diminish the side effects of the vaccine. Perhaps surprisingly, I support RFK Jr’s call for more research on the autism-vaccination link, provided it is done correctly – although see here for the rebutal.
As I mentioned before, I am a sceptical supporter of vaccination. As with other medical advances – sulfamids, antibiotics, prosthetics – they are absolute life-savers.
Since the 1970s, infant mortality has dropped from 10% to below 3% globally. It is difficult to deduce how much of it is due to vaccination and how much to other improvements. There has been fantastic progress in the general public health support, despite the advances of civilisation-related diseases like obesity or diabetes.
It is likely that 2% of this 7% drop is due to vaccination. It might sound small, but I do not think any parent would like their child to be among these 2%.
