The study recently published in the prestigious journal JAMA, and the press release accompanying it, show the implications that a decline in vaccination coverage for several key diseases, particularly measles, would have.

Using mathematical models, the authors establish the possible scenarios that the US could face in the event of a decline in vaccination coverage, as well as the overwhelming increase in the number of cases, outbreaks, associated complications and deaths from diseases that had already been eliminated. The ability to quantify the impact of declining vaccination coverage is the key value of the study, as it provides clear scientific arguments to be presented to health decision-makers, healthcare professionals and parents, who are ultimately the ones who decide whether or not to vaccinate their children.

The message conveyed is extremely important, even more so in the current situation in the United States, where not only anti-vaccine sentiment among the population could jeopardise the elimination of measles, but the government itself is questioning the effectiveness of vaccines.

Does the press release accurately reflect the study?
"Perfectly. It summarises the type of epidemiological model used and the significance of the results in terms of public health. It also clearly states that they have used a conservative model with all the limitations of a heterogeneous population such as that of the United States."

Is the study of good quality? Are the conclusions supported by solid data?
"I am not familiar with the epidemiological method used, but I assume that in a prestigious journal such as JAMA it has been reviewed by expert statisticians and epidemiologists."

How does this work fit in with existing evidence?
"It fits with the epidemiological evidence of measles outbreaks occurring not only in the US but also in other countries."

Have the authors taken confounding factors into account? Are there any important limitations to consider?
"The limitations are clearly specified and consistent in the final section of the discussion."

What are the implications for the real world?
"It has clear implications as soon as a decline in vaccination rates and certain gaps in childhood vaccination are detected. This is a very relevant study, and the epidemiological model used demonstrates the evolution we will see if this decline in vaccination continues. A conservative model was used, with a measles virus replication rate of 12, when it is actually higher (around 20). This model shows that in 20 years, measles will become endemic again, which is a real tragedy.

The other three viruses (polio, diphtheria and rubella) do not behave in the same way, as their replication rate is lower than that of measles.

As the authors themselves point out, we do not know how vaccine fatigue will evolve after COVID-19, but this drop in vaccination rates and herd immunity protecting against these viral infections is very worrying.

The conclusion is clear: if vaccination rates fall, measles will become endemic (not only in the US, but in other countries as well). It does not appear that the same could happen with other pathogens included in the study.

There are currently outbreaks of measles, but vaccination coverage of over 95% is needed to prevent it from becoming a problem, as it is an extremely contagious virus. Vaccination is the best weapon for preventing serious diseases. It should not be forgotten that measles can cause encephalitis and death; it is not a trivial infection as many people believe.