Defining ‘zero-dose’ children and their significance
The term ‘zero-dose children’ is used to describe children who have not received a single dose of a specific vaccine of interest or to describe children who have not received any vaccine at all. The percentage of ‘zero-dose’ children for diphtheria, tetanus, and pertussis-containing (DTP) vaccines is commonly used as a proxy for lack of access to routine immunization services. According to WHO/UNICEF estimates, more than 14 million children worldwide were ‘zero-dose’ for DTP in 2022, with 9.1% of these cases occurring in the Eastern Mediterranean Region (EMR). This is a decrease compared to the 18.1 million children globally in 2021 (1). In 2022, about 20.5 million infants did not receive essential vaccines (2). This marks a decrease from the peak of 25 million children reported as ‘zero-dose’ for DTP in 2021, the highest number since 2009. Additionally, there was an increase of 5 million completely unvaccinated children in 2021 compared to the onset of the COVID-19 pandemic in 2019 (1).

‘Zero-dose’ children face heightened susceptibility to vaccine-preventable diseases, leaving them with little or no protection against severe illness, disability, or death caused by these infections. Beyond individual risk, these children also pose a significant public health concern, as their vulnerability increases the likelihood of disease transmission within communities, particularly to other unvaccinated or under-immunized children. This dual risk underscores the importance of identifying and reaching ‘zero-dose’ populations to strengthen routine immunization coverage and interrupt preventable disease outbreaks.

Regional burden: immunization coverage in the EMR
In 2023, there were approximately 2.85 million ‘zero-dose’ children in the EMR, a significant increase from the previous year’s estimate. This rise reflects a broader regional decline in immunization coverage due to factors including socioeconomic challenges, political instability, and disruptions caused by the COVID-19 pandemic. Specifically, DTP1 coverage in the EMR fell to 85%, and DTP3 coverage dropped to 79%, leaving nearly 4 million children vulnerable to vaccine-preventable diseases (3). An estimated 80% of these ‘zero-dose’ children live in Gavi-eligible countries, including Afghanistan, Pakistan, Somalia, Sudan, and Yemen (4). These countries encompass a diversity of settings with anticipated variability in the drivers of ‘zero-dose’ and under-immunized children, which are complex, interrelated, and highly contextualized (5) ‘Zero-dose’ children in Pakistan alone constitute around 14% of the total ‘zero-dose’ in EMR (3).