Respiratory Diseases Roundup

Vaccine Gaps, Myocarditis Risks, and GI Impacts of COVID-19

Miranda Manier, BA

Key Highlights:

  • Global childhood vaccine coverage has declined in recent years, with over 15 million children unvaccinated in 2023.
  • The FDA finalized enhanced myocarditis warnings for Pfizer and Moderna COVID-19 vaccines.
  • Prevalence of irritable bowel syndrome and chronic idiopathic constipation rose significantly in the United States during the COVID-19 pandemic.

Childhood Immunization Progress Stalls Globally1

An analysis from the Global Burden of Disease Study shows that while worldwide vaccine coverage for routine childhood immunizations nearly doubled between 1980 and 2023, progress has stagnated since 2010 and declined during the COVID-19 pandemic. Coverage for key vaccines—such as the first and third doses of the diphtheria, tetanus, and pertussis vaccine; measles-containing vaccine; oral poliovirus vaccine; and Bacillus Calmette-Guérin vaccine—dropped notably in several countries, including many high-income nations. At the pandemic’s peak in 2021, the number of infants who received no vaccines at all (termed "zero-dose children") reached 18.6 million. By 2023, over half of the 15.7 million zero-dose children were located in eight countries, including Nigeria, India, and Brazil. Although newer vaccines like those for pneumococcal disease and rotavirus saw continued expansion, their growth slowed due to pandemic disruptions. Forecasts to 2030 suggest that only the third dose of the diphtheria, tetanus, and pertussis vaccine may reach the World Health Organization's 90% global coverage target—and only in the most optimistic scenario. The findings call for urgent, equity-focused strategies to reach underserved populations and restore routine immunization services.

FDA Finalizes Heart Risk Warnings for mRNA COVID-19 Vaccines2

The FDA has updated safety labeling for Pfizer’s Comirnaty and Moderna’s Spikevax COVID-19 vaccines to provide more detailed information about the risks of myocarditis and pericarditis. Based on commercial health insurance data, the incidence of these cardiac side effects is approximately 8 cases per million doses in individuals aged 6 months to 64 years, and approximately 27 cases per million in males aged 12 to 24 years. These conditions can result in persistent abnormal findings on cardiac magnetic resonance imaging, although the long-term significance of these findings remains unclear. The FDA noted that these updates are part of an ongoing commitment to vaccine safety monitoring. Both Pfizer and Moderna are required to continue long-term studies on potential heart effects in individuals diagnosed with myocarditis after vaccination. While myocarditis remains a rare adverse event, health authorities continue to emphasize the favorable risk-benefit balance of COVID-19 vaccination, especially for preventing severe outcomes related to SARS-CoV-2 infection.

Irritable Bowel Syndrome Increased During the COVID-19 Pandemic3

A large cross-sectional study of more than 160,000 U.S. adults found that the prevalence of irritable bowel syndrome and chronic idiopathic constipation increased significantly between May 2020 and May 2022. Using the Rome IV diagnostic criteria for disorders of gut-brain interaction, researchers observed that irritable bowel syndrome prevalence rose from 6.1% to 11.0%, while chronic idiopathic constipation increased from 6.0% to 6.4%. Among subtypes, mixed irritable bowel syndrome had the highest growth, followed by irritable bowel syndrome with constipation and with diarrhea. Other gastrointestinal disorders such as functional dyspepsia and bloating did not show significant changes. The authors hypothesized that both the enteropathic properties of SARS-CoV-2 and heightened psychological stress during the pandemic may have disrupted gut-brain signaling. The findings highlight the need for continued investigation into the physiological and behavioral impacts of the pandemic on gastrointestinal health.

References:

  1. GBD 2023 Vaccine Coverage Collaborators. Global, regional, and national trends in routine childhood vaccination coverage from 1980 to 2023 with forecasts to 2030: a systematic analysis for the Global Burden of Disease Study 2023. Lancet. 2025:S0140-6736(25)01037-2. doi:10.1016/S0140-6736(25)01037-2
  2. Walter M. FDA finalizes new heart warnings for COVID-19 vaccines. Cardiovascular Business. Published June 26, 2025. Accessed June 30, 2025. https://cardiovascularbusiness.com/topics/healthcare-management/healthcare-policy/fda-finalizes-new-heart-warnings-covid-19-vaccines
  3. Almario CV, Choi SY, Chey WD, Spiegel BMR. Trends in prevalence of Rome IV disorders of gut-brain interaction during the COVID-19 pandemic: results from a nationally representative sample of over 160,000 people in the US. Neurogastroenterol Motil. 2025:e70020. doi:10.1111/nmo.70020