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The United Nations Children’s Fund has reported that approximately 2.7 million children younger than 1 year in Latin America have incomplete vaccination schedules. Even more concerning is the high number of “zero-dose” children — those who have never been taken to a vaccination center at all. Due to the risks this population faces, experts from the Latin American Society of Pediatric Infectious Diseases are calling for increased regional attention in an article published in the journal F1000Research.

“This article is relevant because discussions around vaccination often focus solely on coverage, which may appear high, while overlooking a significant proportion of children who haven’t received a single vaccine. This creates a serious risk for them, which is why it’s essential to identify and prioritize them for vaccination,” said María Ávila Agüero, MD, pediatric infectious disease specialist, article author, former Minister of Health of Costa Rica, and current head of Infectious Diseases at Carlos Sáenz Herrera National Children’s Hospital in San José, Costa Rica.

Operationally, zero-dose children are defined as those who have never received even a first dose of a vaccine containing diphtheria, tetanus, and pertussis components. The article includes a series of recommendations for improving outreach to this population, based on discussions from a symposium organized by the medical society in late 2023 in Costa Rica.

Latin America lacks precise data on zero-dose populations, though between 2021 and 2022, the Americas saw a 14% reduction in their number — from 1.85 million to 1.31 million. Globally, Mexico and Brazil were among the 20 countries with the highest number of zero-dose children during that period.

In 2023, regional coverage for the first dose of the diphtheria, tetanus, and pertussis vaccine reached 89%. However, there are wide disparities between countries: From 65% in Venezuela to 99% in the Dominican Republic, Chile, Cuba, Costa Rica, and others.

COVID Disrupted Vaccine Programs

“The COVID-19 pandemic changed everything, as resources were redirected to control it, which affected other programs — including vaccination and health education,” Ávila Agüero noted. “Although recovery is underway, it’s uneven and depends heavily on the strength of each country’s health ministry and public policies.”

Aurora Bautista Márquez, MD, a pediatrician with extensive public health experience and former head of the Comprehensive Child Development Division at the Mexican Social Security Institute, who did not contribute to the article, commented: “This article is both interesting and important because it reminds us of a persistent and concerning issue in the region.”

“There is a constant risk of the reemergence or outbreak of vaccine-preventable diseases,” she emphasized.

She also agreed that the pandemic significantly affected vaccination coverage: “At the start of the pandemic, basic vaccination coverage among children under 5 dropped sharply, as many parents avoided taking their children to health centers for fear of SARS-CoV-2 infection.” With the rollout of COVID vaccines, attendance at vaccination centers improved, and so did coverage rates.

“I find the data in this article very helpful, as they allow us to understand the scale of the problem in each country,” added Bautista Márquez.

How to Reach Zero-Dose Children

The article stressed the importance of identifying and characterizing the issue in each country. Understanding who the zero-dose children are, where they live, and why they haven’t been reached is essential. With these insights, countries can tailor approaches and implement effective, sustainable interventions.

In some areas, vaccine supply shortages complicate efforts. In others, access is hindered by distrust, poverty, low socioeconomic status, discrimination, or religious beliefs.

To address the problem, the authors prioritized the need for better nominal electronic vaccination records across the region. These digital tools allow for tracking vaccine data, optimizing supply distribution, and facilitating the rollout of timely, effective strategies.

Bautista Márquez agreed: “In my opinion, the most cost-effective strategy is undoubtedly the creation of nominal systems to accurately track the vaccination status of children.”

Another major point raised was the need to strengthen communication about the benefits of vaccination. Public trust in vaccines — damaged during the COVID pandemic — is a key factor in acceptance. To rebuild that trust, the article calls for evidence-based information campaigns involving community leaders, religious groups, healthcare providers, and other stakeholders.

“Involvement of healthcare workers in shaping public perception of vaccination and education about vaccines play a major role and can help prevent vaccine hesitancy,” the study authors wrote.

On this point, Ávila Agüero urged Latin American physicians not to miss any opportunity to vaccinate. She emphasized the importance of reviewing vaccination cards, approaching families with empathy and respect, addressing concerns, and not minimizing fears. Bautista Márquez added that healthcare professionals must also be well-informed about vaccine contraindications, as a lack of knowledge can lead to many missed opportunities.

Political Will Is Essential

Tackling inequities and ensuring that vaccination programs are equitable and reach all children — regardless of socioeconomic status, ethnicity, or geography — is a pressing task for policymakers in the region.

Vaccines must be readily available and accessible to all children, including those in remote or underserved areas and among migrant populations. The article highlights solutions such as mobile vaccination units, extended clinic hours, and outreach programs that target marginalized communities.

Bautista Márquez noted that while many of the strategies discussed are already being implemented, basic issues — like untimely vaccine supply — have resulted in many children in Mexico being unvaccinated or incompletely vaccinated. “We shouldn’t wait for outbreaks of vaccine-preventable diseases. That’s unacceptable. Measures must be taken to prevent vaccine shortages. Investment is also needed in training and information systems to better track childhood immunization schedules across the region,” she said.

Ávila Agüero underscored the importance of political will in Latin America to mobilize resources and ensure equitable access to vaccination services. “The article expresses concern but also support for the region’s health ministries. It issues a call to action at a time of heightened epidemiological risk,” she concluded.

All authors, along with Bautista Márquez and Ávila Agüero, declared having no relevant financial conflicts of interest.

This story was translated from Medscape’s Spanish edition.