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Home » Babies are safer in the Age of MMR Vaccine than Age of Measles

Babies are safer in the Age of MMR Vaccine than Age of Measles

A recent recurrent claim in the anti-vaccine group is that the MMR vaccine puts babies at higher risk than they were before vaccines when measles outbreaks were large and frequent. The claim is that because vaccinated mothers transfer less immunity than mothers who had wild measles to their babies, babies are less well protected, and hence more at risk. This matters, because rates of complications are higher in babies than others. 

The anti-vaccine claim is incorrect and deeply morally problematic. It’s incorrect because the difference in immunity between vaccinated mothers and mothers who had measles is real, but not huge; and because even if babies of vaccinated mothers are more likely to get measles if exposed, babies were much more likely to be exposed before vaccines.

It’s morally troubling because it assumes that it is acceptable – even desirable – to sacrifice girls to measles so that the survivors will serve to protect their future babies. Embedded in this assumption is a view that girls matter less, or that girls’ importance is in their role as future mothers, not individuals.

MMR vaccine
Photo by Thiago Cerqueira on Unsplashk.

Immunity is slightly longer in mothers who had measles

There is evidence that mothers who had measles provide stronger protection to babies, and that protection lasts longer – but not much longer. Babies generally lose this protection by six months, whether the mothers were vaccinated or had measles:

At 6 months of age, more than 99% of infants of vaccinated women and 95% of infants of naturally immune women had lost maternal antibodies according to the model.

Or this:

The estimated duration of protection by maternal antibodies among infants in the general population, most of whom were born to vaccinated mothers, was short: 3.3 months for measles, 2.7 months for mumps, 3.9 months for rubella, and 3.4 months for varicella. The duration of protection against measles was 2 months longer for infants born in the orthodox communities, most of whom had unvaccinated mothers.

In other words, both natural immunity and vaccinating offers some protection to babies against measles. Natural immunity in the mom does offer better protection – for about two months more. Babies are generally not immune for the whole first year, regardless of whether their mother got sick from measles and recovered or got vaccinated and did not get sick.

Babies more likely to contract measles before MMR vaccine

While babies who lived in the pre-MMR vaccine era were protected for a little longer than babies in the post-MMR vaccine era, they were not safer from measles. That’s because the chances of an unprotected baby in the United States to be exposed to measles were much higher before vaccines.

One of the peak years for measles in the United States has been 2019. There have been, as of August 1, 2019, 1,182 cases.

Before vaccines?

In the decade before 1963 when a vaccine became available, nearly all children got measles by the time they were 15 years of age. It is estimated 3 to 4 million people in the United States were infected each year.

If we go by reported cases, before vaccines there was an average of 400,000-500,000 reported cases of measles each year. 

Let’s assume babies are twice as likely to get measles, if exposed, in the MMR vaccine era than before vaccines. Before vaccines, it seems that the rate in infants was around 5% – actually 5-10%, but let’s be conservative. If we assume that after vaccines it’s twice as much, it’s 10%. 10% out of 2019 1,182 cases would make 118 cases in babies.

If we assume that 5% out of 400,000, the lowest reported number in the pre-MMR vaccine era, is 20,000. Even 1% would be 4,000. That means that thousands of babies likely got measles before the start of MMR vaccinations.

Now, obviously, the chances of a baby to be exposed today are not randomly and equally distributed – they will be higher in communities with low vaccines rates. But in the past, when there was no vaccine, the chances would be randomly distributed – babies anywhere were at risk of measles. Saying babies were safer in the pre-vaccine era then is incorrect.

I have not found a lot of data on measles cases by age before vaccines, but what I found strongly supports the point that more babies got measles before MMR than after. In 1908-1912, in Washington DC alone, there were over 450 infant measles cases. In one place. 

That’s across several years, but it’s one location. In 1938 there were over 400 reported infant deaths in the United States from measles – that is deaths, not cases, suggesting thousands of cases.  The estimate, again, is that 5-10% of measles cases were in infants

Factually, then, trying to claim babies were safer from measles before the MMR vaccine than after is simply and flatly wrong. Babies are safer in a world of no, or almost no, measles than in a world full of measles. So is everyone else.

Photo by The Honest Company on Unsplash.

The moral issue

Further, note that what the claim that having mothers with natural immunity to measles is better assumes. Measles is a serious disease.

In recent times in developed countries, the rate of death from measles (in Europe and the United States ) was about 1:1000. That is not the only harm – measles can cause pneumonia, encephalitis, deafness, and blindness. And the rates of those complications are not low. 

So, people saying it’s better for moms to have natural measles are saying it is a better world if girls get measles in childhood; they are willingly accepting, in fact, saying it’s better when 1:1000 of these girls die, 1:1000 gets encephalitis, some are blinded, some are left deaf, about 1:20 gets pneumonia because the girls who survive can then serve to protect the next generation of babies – when we can prevent measles with vaccines.

This choice downplays the value of girls and treats them as most important as a womb and mother for the next generation. It is jarring and troubling. And really, are we only protecting babies to infect them as young girls?

I expect the people making the argument have not taken it that far and have not considered this aspect. In part, anti-vaccine activists do not acknowledge the rates of measles’ complications. But for the rest of us, an argument that rests on accepting deaths of little girls to use the survivors to protect future babies, when we have other protection, should be morally unacceptable. Girls deserve better.


This article is by Dorit Rubinstein Reiss, Professor of Law at the University of California Hastings College of the Law (San Francisco, CA), who is a frequent contributor to this and many other blogs, providing in-depth, and intellectually stimulating, articles about vaccines, medical issues, social policy, and the law. 

Professor Reiss writes extensively in law journals about the social and legal policies of vaccination. Additionally, Reiss is also a member of the Parent Advisory Board of Voices for Vaccines, a parent-led organization that supports and advocates for on-time vaccination and the reduction of vaccine-preventable disease.

Dorit Rubinstein Reiss

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