Immunization is an essential component of the human right to health, and is the responsibility of individuals, communities and governments. It is estimated that vaccination prevents 2.5 million deaths each year. Children immunized and protected from the threat of diseases preventable by vaccination have the opportunity to develop and more likely to reach their full potential. These advantages are further reinforced by vaccination of adolescents and adults. As part of an intervention plan to prevent and control diseases, vaccines and immunization are an essential investment in the future of a country and even of the world (13).
Vaccination is one of the most beneficial strategies in public health. Scientific, technological and social advances offer great opportunities to expand basic vaccination schedules. (3).
Maximizing the impact of vaccination on public health requires a number of conditions. Among these factors are the need to generate more preventive awareness among the population, the imperative to ensure political support for the healthcare sector in terms of allocation of financial resources for the introduction of new vaccines, and the need to counteract the effect of the anti-vaccine groups (3).
By 2010 WHO established the general goals of the decade 2011–2020: 1. To get a polio-free world 2.- To meet vaccination coverage targets in all countries, regions and communities, 3.- To develop and introduce new and improved vaccines and technologies 4.- To overcome the number 4 Millennium Development Goal on reducing child mortality. If these specific immunization goals were achieved, hundreds of millions of cases and millions of future deaths would be avoided by the end of 2020, and thousands of millions of dollars of productivity would be earn, and immunization would help to achieve the target of the 4th Millennium Development Goal by reducing child mortality (13).
In May 2017, Health Ministers of 194 countries adopted a new resolution to strengthen vaccination in order to achieve the objectives of the Global Vaccine Action Plan. In this resolution, countries are encouraged to show leadership and more robust governance over national immunization programs, to strengthen monitoring and surveillance in order to ensure the use of updated data to guide strategic decisions, to optimize program’s performance and impact of immunization. In addition, it is recommended to expand immunization services beyond infancy, to mobilize internal funds and to strengthen international cooperation to achieve the objectives of the Global Vaccine Action Plan (3).
It is estimated that in 2016, 19.5 million infants worldwide were outside the scope of routine immunization services, like the third dose of the triple bacterian (DTP3). About 60% of them live in 10 countries: Angola, Brazil, Ethiopia, India, Indonesia, Iraq, Nigeria, Pakistan, Democratic Republic of Congo and South Africa (3).
Monitoring data at the national level is critical to assist countries prioritizing and tailoring vaccination strategies and operational plans to fill immunization gaps, and to get people all the shots which can save their lives (3).
According to the latest Pan American Health Organization (PAHO) report on immunization coverage in Venezuela, 2017 vaccination coverage was 100% for BCG, 66% for DTP (3rd dose), 79% for polio (3rd dose), 95% for MMR, and 18% for rotavirus (14, 15).
In the present study it was observed a low coverage for all vaccines in 2019 — a situation already evidenced by WHO in 2017—. An average decrease in vaccine coverage of 21.5% from 2015 to 2019 was verified. The smallest decline in coverage was for the BCG vaccine which only decreased by 6.3%. On the contrary, a significant decline in coverage in the years evaluated was found for the other vaccines, being the more important coverage decline for the rotavirus vaccine (52.2%) followed by influenza, where the drop was 21.1%. These deficits are exacerbated when they are analyzed by age group. The worst case is for children under one year old: coverage for rotavirus dropped 69.2%, and influenza vaccine reaches 0% coverage in the studied population. The coverage drop was less marked for children aged 1 to 6 years, although there was also a significant drop in rotavirus and influenza vaccination rate. In children older than 6 years, significant differences were found in terms of vaccination coverage, except for the case of BCG and Pentavalent vaccine.
Even though pneumococcal vaccine was included in 2013 in the EPI in Venezuela, and began to be implemented in May 2014, a very low coverage of this vaccine is observed. Only 16% of patients had access to full immunization schedule, and a coverage drop of 16.1% is found between 2015 and 2019. This drop is more accentuated for the group of children under 1 year old: in this age group coverage was only 3.5% in 2019.
The scenario just described contrasts with studies in other countries in the region, where it is evidenced lower coverage for children older than 6 years old. For instance, in 2016 Carme Saperas Pérez (7) evaluated vaccination coverage by age group in a municipality of Apartado, Colombia, evidencing correct coverage of hepatitis B and BCG in newborns, with figures ca. 100%. However, as age increases, declining immunization coverage is observed, being for pentavalent in children older than 1 year of 90.7%, 90.15% polio, MMR 88.86%, yellow fever figures critical booster vaccination coverage of DTP and MMR at 5 years of age, which differs from our study, where better vaccination coverage was observed in children aged 12 months to 6 years and in critical figures in children under 12 months old. (7)
In its report of 2017, the Roundtable for Poverty Reduction (Peru) assessed vaccination coverage for full compliance with the basic vaccination schedule in children under 3 years. They found an increase in the overall vaccination coverage from 55.7% in 2014, to 69.4% in 2015 (up 13 percentage points increment) for children under 1 year old —where timely vaccination is a reflection of the quality of care—. The increase in coverage continues in 2016, reaching levels of 74.0% (up 5 percentage points). In the first half of 2017 75.5% coverage (16) was reached.
Decline in vaccination coverage is influenced by several factors, one of the most important being vaccine availability. According to Venezuela’s 2017 EPI report, produced and published by PAHO / WHO, vaccine shortages in Venezuela have increased from 2012 to 2017, with shortages reported in 2012 for hepatitis B and polio vaccines, while in 2017 shortages of pneumococcal conjugate, DTP, yellow fever, hepatitis B, Hib, Influenza, IPV, oral polio and rotavirus vaccines are reported (15). This would explain the decrease in compliance with the recommended immunization schemes observed in the present work, when comparing data of 2015 and 2019.
Low vaccination coverage have caused the rise in previously eradicated diseases as measles and diphtheria. In Venezuela, between epidemiological week 26th of 2017 and the 52th of 2018, 9,116 suspected cases of measles were reported (1,307 in 2017 and 7809 in 2018) of which 6,202 were confirmed (727 in 2017 and 5,475 in 2018). The cumulative incidence rate in the country from 2017 to 2019 is 19.6 cases per 100,000 inhabitants (17); despite this epidemic, it was observed a decline in coverage against measles in the years studied, dropping to 61% coverage for 2019.
There is also an epidemic of diphtheria in Venezuela that started in July 2016 and which is still active in March 2019. 2,512 suspected cases of diphtheria have been registered up to the 2nd epidemiological week of the year 2019, of which 1,559 were confirmed, with 270 deaths (18). However, a decrease in diphtheria’s vaccine coverage was evidenced in the present study. We found a decrease in pentavalent coverage of 80.2% for 2015 and 59.9% for 2019, this decrease being more pronounced in children under 1 year old, for whom coverage for 2019 was 30.6%.
Immunizations represent, after clean, safe water, the most effective way of preventing infectious diseases, one of the most outstanding public health achievements in child health. Hence, the importance of knowing their application cannot be overestimated; systematic vaccinations, particularly at ages in greater risk, will dramatically decrease the incidence of infectious diseases.
The main limitation of the study was to obtain from parents the information on the immunization schedule that many of them did not know the information and lost the vaccination record of their children.