Back in December of last year, I mentioned in a post that one of the complications of the SARS-CoV-2 pandemic was a decline in childhood vaccine rates:
During the peak of the pandemic, when people were trying to stay home and avoid COVID-19, millions of children got behind on their routine immunizations. This was, and is, a worldwide phenomenon. The WHO recently estimated that 40 million children missed a dose of the measles vaccine in 2021 alone, putting them and potentially millions more around them at risk of developing this potentially deadly disease.
At the time, an outbreak of measles was occurring in Central Ohio that ultimately ended in February after 85 children were diagnosed. 36 of these children required hospitalization and all cases occurred in kids who were not fully vaccinated, either because they were too young or because of their parent’s decision to refuse the lifesaving intervention. Thankfully nobody died, although measles carries with it an unfortunate possibility of death even years after the initial infection has resolved.
Measles infection is associated with suppression of the immune system that can last for years, which increases the risk of subsequent infection with other potentially deadly pathogens. This is an excellent example of a vaccine having benefits far beyond simply preventing acute complications of infection by the targeted virus or bacteria, others being the reduction in cases of diabetes linked to the rotavirus vaccine and the prevention of cancer by the HPV and Hepatitis B vaccines.
Measles infection, particularly during infancy, is also a cause of subacute sclerosing panencephalitis, a thankfully uncommon disease that is as nasty as it sounds:
Acute encephalitis occurs when the immune system reacts to measles virus that has found its way into the central nervous system. But the immune system doesn’t always respond aggressively. In some cases, a mutation occurs in the virus which renders it unable to produce certain proteins that would have served as a signal flare. In addition, particularly in children less than 2 years of age, an immature immune system simply fails to respond.
Regardless of the specific reason, measles virus is allowed to remain in neural tissue relatively unchecked and it slowly proliferates under the radar as the years go by. Eventually, usually in the ballpark of 6 to 8 years later, the progressive inflammatory process becomes clinically apparent. Death is almost certain and occurs within 1 to 3 years of diagnosis in most cases, although there are case reports of more rapid progression as well as the occasional patient who survives.
In January, I followed up with a bit more discussion of the unfortunate decline in vaccination rates among kindergarten children in the United States. Data from 2021-2022 revealed a further decline from the previous year, which was already moving in the wrong direction:
The specific vaccines included in the CDC data were the MMR vaccine (93.5%), DTaP (diptheria, tetanus, pertussis, 93.1%), polio vaccine (93.5%), and varicella (chickenpox) vaccine (92.8%). I imagine for many folks 93% seems like a pretty good number, and it would be for Mrs. Peebles’ Biology II class. Unfortunately, for highly infectious diseases like measles we really need to be a bit closer to 100% in order to maintain herd immunity and protect vulnerable people, particularly those who are at high risk of severe disease.
When it comes to vaccine rates, there is significant variation between and within states, largely because of because of the three Ps of healthcare disparity: politics, poverty, and prejudice. Sticking with measles, for example, New York was a clear winner with an MMR vaccination rate of 98%. Great job, you coastal liberal elites. Rhode Island came in second with just over 97%. Let’s all raise a coffee milk toast to all those anti-virus Ocean Staters.
On the other end of the data are states like Alaska (78%), Wisconsin (82.6%), and Georgia (83%). Overall, only 13 of the 49 (what’s your deal, Montana?) states included in the data met the CDC goal of 95% of eligible kindergartners having received both doses of the MMR vaccine. So is most states, and almost certainly even in parts of the others, there are communities that are fully primed for a major outbreak of this horrible disease.
Now a bit of good news (but don’t get too excited)
There appears to have been a bit of a post-pandemic rebound in worldwide childhood vaccinations in 2022, though not in every country and we still have a ways to go overall. Historically the UN has focused on diphtheria, tetanus, and pertussis (DTP) vaccines as a marker of general uptake in communities. With this in mind, the UN recently announced that 20.5 million children missed at least one dose in 2022, which is an improvement of 4 million children compared to the year before. In 2019, roughly 18 million children missed a DTP dose, making it clear that the pandemic only exacerbated an already worrisome reality.
I picked out a few interesting numbers reported by the UN this month to share, but there is a lot more. Please check out this detailed discussion of the report.
- The number of children who received zero vaccine doses in 2022 improved from 18.1 million to 14.3 million. It was 12.9 million in 2019.
- Children getting their first dose of measles vaccine increased from 81% to 83% in 2022, but even the pre-pandemic level of 86% is terrible and we need to do better.
- 21% of eligible girls got their first HPV vaccine in 2022, up from 16%. Also terrible.
- Less than half (48%) of eligible at risk children got a yellow fever vaccine. We are shooting for 80%, so not great.
- Global coverage with 3 Hib vaccine doses was 76%, with significant variation between regions. 93% of kids in the WHO European Region were fully vaccinated compared to 32% in the Western Pacific Region. Hib meningitis is a nightmare (1 in 20 die, 1 in 5 suffer permanent brain damage/deafness despite proper treatment) and, again, we need to do much better.
If you are concerned that this improvement in vaccine rates was mostly only seen in certain countries, perhaps those with more available resources, you are intelligent, compassionate, and probably pretty good-looking to boot. The above linked article from UN News points out how numbers in aggregate can be misleading:
The early stages of recovery in immunisation rates have not occurred equally. Progress in well-resourced countries with large infant populations such as India and Indonesia, masks slower recovery rates, or even continued declines, in middle and low-income countries.
The UN adds that 34 of the 73 countries that had significant decreases in childhood immunization numbers during the first two years of the pandemic were worse off or saw no improvement in 2022. Of the countries that did improve, only 15 got back to pre-pandemic rates. And truly unfortunately, because it is such an infectious and dangerous disease, measles vaccination continues to lag behind even in some countries that are otherwise doing better overall. More than 33 million children missed a measles dose last year, leaving many communities at risk of outbreaks.
An international effort is currently underway to remedy these gaps in vaccine coverage. Calling this push “The Big Catch-Up“, the WHO, UNICEF, Gavi, The Bill & Melinda Gates Foundation, and others are working with governments to get missed doses to kids all over the world. It’s going to take a lot of money, of course, to make this happen, as well as widespread policy changes that improve access in low resource regions. Just as important is the need to combat anti-vaccine propaganda and reduce vaccine-hesitancy.