If, like me, you were a child in the late 50’s, you were probably not terribly concerned by the recent stories about an uptick in measles cases in Canada and other rich-world countries. Health Canada reports that as of May 4^th, there have been 75 reported cases of measles in Canada this year. There were 1, 0, and 3 cases reported in 2020, 2021 and 2022 and then 13 in 2023. So that data marks a definite upturn – far more than statistical variation.

 I had measles as a child and so did pretty well everyone else in our family. Nasty, but not really a big deal, right? But then this week came the sad news that a child in Hamilton, Ontario had died from measles, the first such fatality since at least 1989, the last year for which Ontario has retained measles case monitoring.

Measles isn’t just a minor childhood inconvenience. It can be a big deal. A research article by Michael J Minia et al in Science magazine in November 2019 tells us that measles is “endemic in much of the world, affecting >7 million people annually and causing >100,000 deaths.” A hundred thousand deaths worldwide, annually! I wouldn’t have imagined anything like that amount of impact.  Measles evidently is both virulent and very contagious.  If you’re in contact with an infected person and you are not immune, the probability that you’ll get it is about 90% according to Health Canada.

The common symptoms of measles are the rash that one associates with measles, as well as fever, cough and runny nose. Less common and more severe complications include encephalitis, neurologic complications, and respiratory failures, leading to death in 0.1% to 0.3% of cases. For those fortunate enough to survive the severe measles complications, long term effects may include blindness, deafness, and “damage to the central nervous system that results in cognitive, sensory, or motor deficits that may also manifest as emotional instability and seizures in the most severe cases.”

Not only is measles a dangerous disease in its own right, it’s a sneaky back-stabbing little bitch. The Minia article I mentioned above documents an investigation of children in the Netherlands in a low- vaccine uptake community. The community agreed to have blood sample taken from healthy children. Following a measles outbreak in which 77 of those children caught measles, more blood samples were taken. Blood sample analysis showed that many of the antibodies for other diseases had disappeared – from 11% to 73% reduction. In other words, measles attacked the immune system and left the kids vulnerable to other diseases. The authors report that epidemiological evidence suggests that “In the pre-vaccine era, measles virus may have been associated with up to 50% of all childhood deaths from infectious diseases, mostly from non-measles virus infections.”

Prior to the introduction of a measles vaccine in 1963, there were fairly typically 35000 to 40000 cases per year in Canada.  With a fatality  frequency of 0.1 to 0.3 %, that means that annual deaths from measles were somewhere between 35 and 120 in Canada. The measles vaccine in 1963 morphed to a 1 dose measles mumps and rubella (MMR) vaccine in 1974 and to a 2 dose MMR protocol in 1996.  What impact did those vaccines have? Since 1995, reported measles cases are typically less than 100 and there has never been a year with greater than 1000 cases. If any of you doubt the efficacy of measles vaccines and vaccines in general, I invite you to explain that sequence of events. Why did measles all but disappear if it wasn’t because of the vaccine?

I won’t bore you with more data, but I can assure you that the same pattern can be shown for polio. And I’m willing to bet a beer that I can find similar data for any one of the dozen or so infectious diseases for which we now have vaccines.

The Minia article tells us that “after decades of decline, the number of worldwide cases of measles has increased by nearly 300% since 2018 as a result of reduced vaccinations.”  Infectious diseases specialist Dr. Allison McGeer is quoted in a CBC article (Lauren Pelley, May 18, 2024) on the Ontario fatality saying “There’s also a certain aspect of inevitability to it just because of how much ground we lost in measles vaccination around the world.” Public Health Ontario reported in March that “in Ontario, for instance, the proportion of seven-year-olds who had zero vaccine doses rose dramatically, from less than four to nearly 17 per cent, between the 2019-2020 season and 2022-2023.” 

Health Canada website has posted a schedule for recommended vaccinations for your children (or grandchildren) from birth to age 17. It lists 16 different vaccines, many of them to be administered several times and some, like the influenza vaccine to be given annually. Measles vaccines aren’t started until the 12^th month because “residual maternal antibodies may reduce the response rate to the vaccine“. The first measles dose is about 85% efficacious, while the full MMR series provides very nearly 100% protection. But until the MMR series has been received, children are at risk. In the first few years of their lives, they are really relying on herd immunity preventing them from contacting the measles virus, because of that very high infection rate among the unvaccinated.  And of course, with slightly different timelines and risk profiles, the same is true for other diseases like diptheria and polio. It seems incredible to me that, as a society, we are allowing diseases that once were thought to be eradicated to regain a foothold and threaten our babies. 

The worldwide decline in vaccinations isn’t limited to measles either. I’m going to switch tracks a little here, and talk about vaccines for diptheria, pertussis and tetanus (DPT) instead of measles. I need to do that because the WHO uses the DPT vaccine coverage as a metric for overall vaccination program health. 

An article published online in the US National Library of Medicine web-site says “in July 2022, WHO and UNICEF sounded the alarm around the largest sustained decline in childhood vaccinations in three decades, with 25 million children missing out on one or more doses of the vaccine against diphtheria, tetanus, and pertussis. Coverage now stands at its lowest level since 2008.” The target for the DPT vaccine is 95% of children receiving three doses with the target known as DPT3. 

The Covid pandemic has had a significant impact on vaccine coverage – “In 2021, only 63 countries’ DTP3 coverage rates exceeded 95%, with 112 countries experiencing losses in DPT3 uptake in the period 2019 to 2021.” The pandemic disrupted public health organizations and made the delivery of vaccines more difficult. It also introduced a heightened level of vaccine hesitancy into the community based largely on the spread of misinformation about the Covid vaccines, coupled with negative reaction to Covid vaccine mandates. However, we can’t blame the decline entirely on the pandemic. The decline started well before the pandemic.  A net 26 countries dropped below the 95% DPT3 target in the period from 2011 to 2019.

In the United States, the Centre for Disease Control (CDC) published survey data showing that pediatric vaccination rates have shown an annual decrease of 1% in vaccinated children, dropping from 95% in 2019 to 94% in 2020, and further decreasing to 93% in 2021 for measles-mumps-rubella (MMR), diphtheria-tetanus-pertussis (DTP), polio, and varicella vaccines. These numbers reflect national averages, with some areas of the country being far worse than others.

         You might think that a drop from 95% to 93% isn’t all that significant. You might be right. But you might be wrong too. 

I’ve been struck between the similarity between how herd immunity works and how nuclear fission reactor control works. In a nuclear reactor, each fission produces approximately 2.4 free neutrons. If exactly one of those neutrons causes another fission, then power stays the same. If fewer than 1.000 neutrons cause a new fission, then power declines and will eventually fall to near zero. If greater than 1, then power takes off and possibly goes out of control. 

In disease spread, we are the uranium atoms and the virus is the neutron. The infected person passes the virus on to others. If they are vulnerable (unvaccinated) they probably (90%ish) become infected and pass it on to their contacts. Whether the spread of infection is declining or increasing is thus strongly linked to the probability that the infected person’s contacts are vulnerable.  Vulnerability, of course, is linked to the fraction of the population that has been vaccinated or who have previously had measles. WHO has set a herd immunity target at 95% vaccination. One assumes that there is some safety margin in that number, but clearly there is a tipping point – a vaccine coverage rate below which the population at a whole is at risk of a serious disease outbreak. So, staying above that target is a significant public health imperative. 

And that leads us to ask what the hell’s going on with immunization efforts? I’ve looked at the survey data about why vaccination levels are on decline. Reasons given include the following:

• Religion
• Autism conspiracy theory
• Faulty risk assessment
• Inconvenience
• “freedom” 
• Distrust of institutions/Science
• Economics of underdeveloped countries

I must delay an exploration of those reasons to my next installment of CurleyCues, because this article will get uncomfortably long if I don’t.

In the meantime, I want to urge you to speak out against the anti-vax crowd at any and every opportunity. I hope that the poor parents of that child in Hamilton didn’t wilfully withhold vaccination because they bought into some of the stupidity that is being offered. What a terrible burden that would be for them to carry. But it would be nearly as painful to realize that your child died because society turned its back on vaccinations and threw away the protection that we’ve been afforded, wouldn’t it? But that’s what’s happening when other people are refusing their vaccinations – they are putting other people at risk. I’m not cool with that. 

Next time I’ll try to look at all the things that stop people from staying up to date on their vaccinations. I warn you in advance that I’m not sympathetic to most of those positions!