May 18, 2019

The Non-Specific Effects of Vaccination

With all the articles about measles and measles vaccine in the news these past few weeks, I am reminded about a topic I wrote about in 2013, the Non-Specific Effects of Vaccination. This term describes an interesting phenomenon - vaccines provide protection against a range of infections besides the infection caused by the organism from which the vaccine is made and which it is intended to prevent.

Looking specifically at the measles vaccine, in 2013 I wrote:

A 2013 African study reported that the measles vaccine cut deaths from all other infections combined by a third, mainly by protecting against pneumonia, sepsis and diarrhea. In developing countries, measles-vaccinated children have lower mortality rates from all infectious diseases.1,2 In 2005, Veirum reported that measles-vaccinated children had a 49% decreased risk of fatality from infectious disease. In pneumonia cases there was a 72% decrease risk of dying in the vaccinated children.3

The measles vaccine appears to cancel out the negative impact of diphtheria (DPT). In a randomized trial conducted from 2003 to 2009 in Guinea-Bissau, an additional dose of measles vaccine was given at 4.5 months. The children had received three DPT shots prior to starting this study. Compared to children who received measles vaccine at 9 months of age, children who received the vaccine at 4.5 months and 9 months had a 30% decrease in all-cause mortality up to 3 years of age. Less than 5% of this reduction in mortality could be explained by measles prevention.”4

Now of course the sort of vaccination studies we are quoting here are done in Third World countries where it is more common for children to die of infections and thus these changes in mortality are more dramatic. Still these data argue against the common belief that vaccines weaken a child’s immunity and somehow handicap the immune system. At least when it comes to the measles vaccine specifically.

We would be remiss to not take a moment to check for updates.

A somewhat complex but quite fascinating study was published in February 2019. These earlier studies tell us that the measles vaccine lowers mortality from infectious disease. This new study tells us that being vaccinated against tuberculosis (TB) increases this protective effect. Children who were immunized against tuberculosis using bacille Calmette-Guerin (BCG) are easy to spot. One doesn’t need medical records because the vaccine leaves a scar.

In kids, “… having a BCG scar was associated with a 41% …. lower mortality between the ages of 4.5 and 36 months.” Here’s where it gets interesting. The increased immunity against all disease was even more pronounced if the child’s mother also had a scar. “The reduction in mortality was 66% …. if the mother also had a BCG scar but only 8% …. if the mother had no BCG scar.” Thus at least with TB vaccinations, the benefit builds up over successive generations.5

There are two ways to think about these measles vaccine effects. The first and simplest way is that the “measles vaccines … enhance innate and adaptive immune responses.” But actually, it is more complicated. That’s because catching measles, the actual disease, injures the immune system leaving the child more vulnerable to infection long afterwards. The “invisible hallmarks of measles infections [are] increased vulnerability to non-measles infections in nearly all children for weeks, months, or years following acute infections. By depleting measles incidence, vaccination has had important indirect benefits to reduce non-measles mortality.”6

Some research suggests that this immune suppression lasts as long as 30 months. An interesting paper set to be published in June 2019 uses historical medical records to look at three distinct periods of time when past outbreaks of measles and whooping cough overlapped. In a period between 1904 to 1912 risk of whooping cough in those who had measles increased 85-fold. Between 1922 and 1932 whooping cough risk increased 10-fold after a measles infection. And then between 1946 and 1956, whooping cough risk increased 36-fold post measles infection.7

A study of children in the United Kingdom, published in November 2018 compared risk of infectious disease in 2,228 children who had measles against nearly 20,000 children who had not. Risk of non-measles infections persisted for the full five-years the study collected data. During the first month risk of infection was 43% higher in the measles kids but even at five years it was 15% higher.8

The scientific understanding of how vaccines act, particularly in regard to measles, certainly appears to be a work in progress with new insights coming to light on a regular basis. The public discussion on the other hand often seems to be relying on data and on perceptions that are old and outdated. It seems that being infected with measles causes lasting damage to immune function that persists far longer than ever imagined. The measles vaccine, by preventing infection, also protects against this secondary immunosuppression. Luckily, we no longer have significant infected populations so we may never have the option of tracking long term health consequences. Then again, given the current epidemic and the continuing reluctance of some people to be vaccinated, this may prove wrong and we may have enough people to track over time. Time will tell.

Our original 2012 article: The non-specific effects of vaccines

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