Polio: An unfortunate reminder of the decline in routine vaccinations

Yesterday, an unvaccinated, young adult was diagnosed with polio in New York and developed paralysis. They had no history of travel. This case follows a U.K. warning last month after London found several wastewater samples of the polio virus. Both instances suggest local community spread.

While the U.S. and many other countries use vaccines with an inactive virus, some countries use a lower cost vaccine with a weakened live virus. In some cases, the weakened virus can mutate and people can shed the contagious virus in their feces for several weeks (this is called a vaccine-derived polio case). It’s possible that a traveler lands in the U.S. with polio (the last documented case was in 2013), and it’s not unusual for London wastewater to pick up polio a few times a year. But it is very concerning that we see local community spread after we eliminated the virus in the 1970s.

This news doesn’t change anything if you or your children are fully vaccinated. You’re protected. (If you are unvaccinated, this should be a wake up call.) On a population-level, this is a sign of just how hard it is to eradicate a virus. It also highlights a larger theme bubbling to the surface in public health: a decline in routine vaccinations.

Unfortunate trend

Over the past few years, we’ve seen a local and global decline in routine vaccinations. Last week, the WHO reported global coverage of diphtheria-tetanus-pertussis (DTP3) vaccine among infants dropped from 86% in 2019 to 81% in 2021. Global estimates of coverage with a polio vaccine similarly decreased. This followed a November 2021 WHO health warning citing the largest increase in children unvaccinated for measles in 20 years. (During 2020, more than 22 million infants missed their first dose of measles vaccine—3 million more than in 2019.)

Individual countries are also sounding the alarm. The U.K. issued a measles health warning in February 2022, as only 85.5% of children were vaccinated. (Measles needs about 95% vaccinated to reach herd immunity.) In the U.S. during the 2020-2021 school year, 94% of kindergartners had all required vaccines, which is high, but a drop below the target of 95%. The overall U.S. polio vaccine coverage is 92%—below the target set by the WHO to control the virus.

The decline in routine vaccinations in recent years has been largely attributed to two things.

Access to care during the pandemic

At the beginning of the pandemic, disruptions in pediatric healthcare significantly impacted routine vaccinations among children. A JAMA study found the rates of weekly vaccinations across all pediatric age groups declined substantially during the early months of the pandemic, with the most drastic effect among children aged 4-6 years old. Racial disparities also emerged: Asian children were most up-to-date with vaccinations while African American/Black children had the lowest rate. Vaccines gradually returned to pre-pandemic levels for some age groups, but not all.

Another study published in Pediatrics found that, despite rates of specific immunizations, like measles, recovering to pre-pandemic levels, total rates of up-to-date vaccinations remained lower compared to pre-pandemic rates.

Vaccine hesitancy

There’s no doubt the pandemic exposed the intricacies of vaccines to the public. But it also exposed significant COVID-19 vaccine hesitancy among parents. It’s okay to have questions about the vaccines, as long as we can get evidence-based information to people in need. Many fear COVID-19 vaccine hesitancy will spill over to other routine vaccines and feed the already growing anti-vax movement. As Dr. Peter Hotez said in an interview: “[Anti-vaccine activists are] not going to stop at Covid vaccines. Their goal is to discredit all childhood vaccinations. This is going to become another battleground—trying to prevent childhood vaccinations from reaching baseline.” 

A study published last week in JAMA assessed trends in parents’ confidence in childhood vaccines during the COVID-19 pandemic. They found parents’ concerns about safety and side effects for routine childhood vaccines increased between April 2020 and March 2022. Similarly, results from a February 2022 YouGov poll were not great: When asked whether parents should be required to have their children vaccinated against specific diseases, 71% said yes to MMR, 55% said yes to other infectious diseases, and 48% said yes to COVID.

Bottom line

With a decline in vaccinations during the pandemic and increase in vaccine hesitancy, we should expect cases of diseases that have been largely silent, like polio, to now pop up. We are going backwards. We cannot lose decades-long progress towards eliminating vaccine-preventable diseases.

Love, YLE and Sara Stephens, MPH

---

Sara Stephens is a third year PhD student at the University of Texas Health Science Center, School of Public Health, with an interest in childhood vaccines. She significantly contributed to the research and writing of this newsletter article.

“Your Local Epidemiologist (YLE)” is written by Dr. Katelyn Jetelina, MPH PhD—an epidemiologist, biostatistician, wife, and mom of two little girls. During the day she works at a nonpartisan health policy think tank, and at night she writes this newsletter. Her main goal is to “translate” the ever-evolving public health science so that people will be well equipped to make evidence-based decisions. This newsletter is free thanks to the generous support of fellow YLE community members. To support the effort, please subscribe here: