This study adds to the growing pool of literature concerning vaccination trends before and during an Ebola outbreak, and is the first from the DRC, a country that has experienced the most EVD outbreaks since its discovery in 1976. There was a significant decrease in the number of vaccine doses administered monthly for all antigens received during the Ebola outbreak (August-October 2018) as compared with the pre Ebola period (May-July 2018). Our results corroborate those found in several other countries affected by EVD [11, 16].
Additionally, there was an overall reduction in the number of children vaccinated during the “Ebola period”, which is consistent with the notion of reduced health services use secondary to community perception of increased risk of contracting Ebola. This, coupled with the ‘no touch’ policy in which health workers were ordered not to practise invasive procedures, might have contributed to the reduction in the number of vaccines provided, as most vaccines (except polio vaccine) require an injection into either the upper arm or thigh. The priority of Ebola response and control, coupled with constraints in logistical support to ensure vaccine delivery and timely reporting, may also have played a role in the decline in vaccination coverage among health facilities in the areas most affected by Ebola.
Furthermore, rumors surrounding the current Ebola outbreak (some local residents suspect a man-made Ebola outbreak by those military groups that have been killing civilians) - in an area ravaged by two decades of insecurity due to armed conflicts and extreme violence – might have spread the fear among the eastern Congo population [17, 18]. This fact might have also contributed to reducing vaccines uptake in affected areas.
In regards to child vaccination in the context of EVD outbreak, another study reported that numbers of BCG, pentavalent, and measles vaccine doses administered remained relatively stable, with some decreases. Our study reveals a sudden shrink in vaccines uptake in two of the four surveyed Health Zones, whereas a total absence of vaccine uptake (for all vaccine types) was observed in Mabalako Health zone where the epicenter of the EVD epidemic is located, in the three month-period (from August to October 2018) following the declaration of the outbreak.
In the context of the ongoing Ebola outbreak in DRC, a look at data on child immunization activity during a similar period (August-October) in 2017 showed that routine vaccination was implemented regularly in Mabalako Health Zone, with OPV reaching over 1,000 doses delivered (1,416 doses in August, 1,191 in September, and 1,248 in October 2017). Thus, the ongoing eastern Congo EVD outbreak caused large losses in vaccination outputs, leaving young children at significant risk for infection with life-threatening illnesses, as well as potentially putting adults at risk through the breakdown of community-level herd immunity .
Epidemics of measles are often an early result of interruptions in the delivery of public health services. Historically, measles outbreaks have followed humanitarian crises, such as war , natural disasters and political crises . Measles is one of the most transmissible infections, and immunization rates tend to be lower due, in part, to the age at which measles vaccine must be administered .
Based on surveys from health care providers, it was assumed that a 75% reduction in vaccination rates has been observed after the west African Ebola outbreak, with the projection that the number of children between 9 months and 5 years of age not vaccinated against measles would increase by an average of almost 20 000 every month, reaching more than 1 million unvaccinated children by 18 month . Similar reductions in the rate of vaccination would increase the number of children not receiving a pentavalent vaccine, BCG and oral polio vaccine.
The setbacks in vaccination rates observed in Ebola-affected area have the potential to erode the substantial gains in the control of these diseases made in recent decades, and a large population of children susceptible to poliovirus infection could threaten the Global Polio Eradication Initiative, should wild poliovirus be re-introduced. However, childhood vaccine-preventable diseases (VPDs) are an area where there is a clear, relatively inexpensive, and one-time intervention that could erase the impact of Ebola related health care disruptions.
Coordinated campaigns across Ebola affected Health Zones should include targeting children who were most likely to have missed one or more critical routine vaccinations to prevent the occurrence of VPDs [22- 24] such as Measles during the Ebola epidemic. More importantly, a campaign should target children aged 6 months to 5 years (typical of the age range targeted by follow-up supplementary immunization activities (SIAs), perhaps extending the lower age range and administering childhood vaccines other than measles vaccine to the youngest children. Planning for such an immunization campaign should begin imperatively in order to reduce the risk of disease outbreaks in children population.
Nonetheless, the present study has some limitation. The assessment of vaccination coverage was limited to the health zone that was the first to be affected and three other Health Zones located quite close to the epicenter. This was based on the assumption that health zones near the epicenter would be the most affected at the early phase of the Ebola outbreak. On the other hand, the reduced number of vaccinations could have been caused by other factors such as underreporting of routine immunization due to EVD outbreak in the area. However, after interviewing the Health Zone managers, neither such an issue nor a shortage in hospital personnel was noted.