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Vaccination in humanitarian emergencies

  • Page updated onMarch 15, 2025
Vaccination in humanitarian emergencies
Photo: Bruno Abarca

Vaccines are essential tools for the prevention and control of infectious diseases. Vaccines have been available for many feco-oral, respiratory or sexually transmitted diseases for years. In addition, new vaccines have continued to be launched, such as those for malaria, Ebola or COVID-19. Other new vaccines are in the process of research and development.

However, in humanitarian emergencies access to vaccines and the ability to use them effectively is reduced. This is in addition to the increased transmission of infectious diseases that also occurs in these contexts. Both, together, result in a worrisome increase in preventable morbidity and mortality. This problem, combined with the other difficulties in ensuring access to essential services in crisis settings, makes it necessary to adapt strategies and programs of vaccination in humanitarian emergencies.

The stagnation in global progress in vaccination

Vaccines have saved more lives than any other medical innovation

The first vaccine against smallpox -a disease that has already been eradicated-, developed by Edward Jenner in 1796, has been followed by many others. Thus, in the first half of the 20th century, others were developed, such as that against yellow fever in 1938. This earned Max Theiler a Nobel Prize. Advances continued in the second half of this century. In fact, in this period appeared, for example, those of polio between 1954 and 1960 and that of measles in 1963. Since 1986, we have even had the recombinant vaccine against hepatitis B, developed by genetic engineering. These developments continued into the 21st century, with the vaccine against papilloma virus in 2006. This was followed by a new (and better) vaccine against meningitis A in 2010, and the most recent vaccines against ebola, malaria and COVID-19.

It is estimated that since 1974 vaccines have prevented 154 million deaths worldwide, including 146 million in children under five years of age. Thus, they have been responsible for 40% of the reduction in under-five mortality in this period. This reduction has reached 52% in Africa.

Vaccines have been incorporated into routine vaccination programs

The different countries have made great efforts to establish their immunization programs. Alongside them, in addition, there have been global health initiatives such as the Expanded Programme on Immunization of 1974 or the Children's Vaccine Initiative of 1991. Gavi (The Vaccine Alliance) was also created in 2000, as well as the Global Vaccine Action Plan 2011-2020, and the current Immunization Agenda 2030 in following years.

In the first vaccination programs, there were 6 vaccines: tuberculosis, diphtheria, tetanus, pertussis, polio and measles. From that number we have come to have 13 universally recommended vaccines. These include the above plus papilloma, hepatitis B, varicella, pneumococcus, Haemophilus influenzae type B, rotavirus and COVID-19. In addition, there are other 17 more recommended depending on the context, such as those for yellow fever, cholera and meningitis.

All this led to achieving, in the 1990s, global childhood vaccine coverages close to 80%, and great optimism.

Still, millions of children are not adequately vaccinated

Despite progress, it is estimated that, each year, 7 million newborns fail to receive the full package of essential vaccines they need. What's more, another 13 million children do not receive a single dose.

Today we barely have an overall coverage of 83% for the third dose of diphtheria, tetanus and pertussis (DTP3). Similarly, we barely achieved coverage of 74% for the second dose of measles, or 65% for the third dose of pneumococcus, for example. None of the vaccines introduced in recent years have reached the coverage of the older vaccines. This is despite the fact that some of them have been on the vaccine schedules for more than 10 years.

In addition, there are wide differences between countries. DTP3 coverage barely reaches 73% in Africa, and 60% of children who have never received any DTP doses in 2023 live in just ten countries. These are Afghanistan, Angola, DRC, Ethiopia, India, Indonesia, Nigeria, Pakistan, Sudan, and Yemen.

Within the same country, there are also differences between rural and urban areas. Likewise, in countries such as India or Afghanistan, vaccination coverage in girls seems to be lower than in boys. In any case, the greatest difference exists according to the wealth and educational level of the parents. In fact, poorer households are always more exposed and vulnerable. For example, studies suggest that there are 27% fewer fully vaccinated children if mothers have had no formal education. A similar difference exists between the poorest quintile of the population and the richest quintile.

Achieving the "last mile" in vaccination coverage is a major challenge

Today, progress has stalled. In fact, we are still far from the 90% target for coverage for essential childhood vaccines. These include 3 doses of diphtheria, tetanus, pertussis, and pneumococcus, 2 doses of measles, and 1 against papillomavirus.

Reaching that "last mile" from 80% to 90% is of course difficult. In any case, it is further complicated where healthcare systems are weak and have failed to adapt to new demographic patterns. The problem also increases when contradictory information or misinformation contributes to reducing the population's trust in the health authorities. In addition, we cannot ignore the impact of the increase in the number and duration of complex humanitarian crises and conflicts, which pose additional challenges.

Along with the above, since 2020, there has been a setback. This is, in large part, attributable to the indirect effect of the COVID-19 pandemic. Indeed, it is believed to be the result, in part, of redirecting numerous child health resources to epidemic control, Of course, the effect of restrictions and fear of infection on access to health services strained by the crisis has also weighed heavily. In addition, there were many doubts about the safety of a rapidly developed vaccine against a disease that many perceived to be of little seriousness. These doubts have affected public confidence in other vaccines.

Vaccination in humanitarian emergencies requires adaptation of strategies and programs

Vaccination campaigns may be necessary in emergencies

Logistical and security challenges are even greater in a humanitarian crisis. These can increase difficulties in the provision of health services or population access to such services, thus reducing vaccination coverage. It is therefore necessary to consider alternatives to health service provision and routine vaccination programs.

One of the most common strategies of vaccination in humanitarian emergencies is to develop mass campaigns in health units or in the community. This is done outside routine vaccination services, which may or may not be operational. The campaigns target expanded age groups, covering only some priority vaccines, and sometimes with reduced schedules. This solution, which in normal situations could be inadequate, is often the most indicated in complex crises. In these circumstances the ideal is far from realistic.

Humanitarian action must, of course, seek to protect and, as soon as possible, assist in the recovery of the local health system. However, restoring routine vaccination services may take a long time. In the meantime, actions must be adapted to the urgent needs of the population. Nigeria is a good example of the success of such an approach. This country had routine polio vaccination coverages around 60%. However, emergency vaccination campaigns promoted by the Global Polio Eradication Initiative succeeded in protecting the country from wild poliovirus circulation.

Campaigns of vaccination in humanitarian emergencies should prioritize only certain antigens

To decide which vaccines are a priority, it is recommended to establish a working group led by the Ministry of Health. In its absence, leadership can come from the health cluster. This group of expert individuals should:

  1. First assess the epidemiological risks of the different diseases.
  2. Then analyze the different vaccines available and the possibility of offering them effectively.
  3. Finally, study other considerations. These include possible barriers and facilitators, as well as viable alternatives to the initial plan. At this stage, the other humanitarian needs competing for scarce resources should also be analyzed.

Analyzing epidemiological risks helps to identify priorities

The first step requires determining the level of risk of each vaccine-preventable disease, due to general and specific risk factors. It makes no sense to prioritize a vaccine for a pathogen that, in a given context, does not pose a health risk.

The analysis should prioritize the potential mortality resulting from the transmission of a disease. In addition, it should assess the pressure on curative health services and the long-term effects of the disease. These include, for example, papillomavirus cervical cancer or vertical transmission of hepatitis B in childbirth. It may also consider the potential setback in global advances in the elimination or eradication of a disease.

The second step is to evaluate the available vaccines

At this stage it is key to analyze the characteristics of the vaccines and the feasibility of their use.

It is necessary to analyze the potential availability of sufficient doses and the recommended administration schedule. In some cases, the possibility of using reduced or even fractionated doses should also be considered. Sometimes it is unrealistic to expect to apply a complete vaccination schedule if the population is on the move or if availability is reduced. The use of a reduced pattern or a fractionated dose tends to generate less durable immunity than usual. However, it may be sufficient to reduce the risk in the most critical period.

The feasibility of vaccination in a given context also depends on other factors. Examples include its presentation (single or multiple doses), its composition, the type of vaccine (attenuated or inactivated), or the cost. In some cases, a determining factor may be the sensitivity of the vaccine to temperatures. The cold chain can be a challenge in remote areas with poor infrastructure. The time it takes for vaccines to generate a protective immune response against pathogens is also a determining factor. Attenuated vaccines can provide sufficient protection with only one or two doses in as little as two weeks. However, inactivated vaccines require more doses, spaced several weeks apart, to provide a similar level of protection. Similarly, depending on the time of year or seasonal risk of certain diseases, some vaccines may be prioritized and others postponed.

Possible vaccination strategies should also be evaluated

Aspects such as the difficulty of accessing certain geographic areas and populations may be determining factors. It should also be analyzed whether it would be more appropriate to use a fixed post strategy (in health centers, schools, churches, mosques or markets) or mobile teams. This is important, for example, for nomadic populations without access to a fixed vaccination post. Sometimes it may be necessary to combine both approaches. At other times, however, it may also be feasible to try to re-establish routine vaccination services from the outset. In addition, it should be assessed whether there are sufficient personnel and material resources, such as means of transportation, fuel, or refrigerators, to cover the target population.

A key factor is whether it is possible to ensure adequate information and awareness of the population about vaccines in the limited time available. For this, social mobilization is key. It is important to employ multiple channels, from the media to traditional and religious leaders to community and community health workers. In addition, it is essential to understand the population's doubts and perceptions about the risk of infection and their view of vaccines. In this way, messages and the way they are communicated can be properly tailored.

Despite the importance of this dialogue, in emergencies and due in part to logistical difficulties, difficult decisions sometimes have to be made. In some cases informed consent may be limited to verbal consent. Even in extraordinary cases of severe public health emergencies, authorities may determine that vaccination is mandatory. Both can generate significant ethical dilemmas.

In the third step, other considerations and possible dilemmas are discussed

The third and final step in decision-making on vaccination in humanitarian emergencies is based on the analysis of ethical and political considerations. Safety aspects, other concurrent needs to be considered, and contextual factors that may pose barriers to vaccination must be evaluated.

From an ethical point of view, it is often not easy to decide that the vaccination campaign should leave certain lower-risk groups unprotected. After all, they have the same rights. Nor is it easy to balance the importance of community involvement in decision making with the need for rapid action. In addition, the insecurity of the population and health personnel in conflict zones is always an aspect to consider and manage.

Finally, we cannot forget the ongoing humanitarian dilemma of having to prioritize some interventions or populations over others. The reason is clear: there are never enough resources for everything. Sometimes, starting a vaccination campaign against a pathogen can consume resources that could be used for other health problems. Likewise, opting for some vaccines and not others will benefit some people and harm (or not benefit) others.

Not all decisions about vaccination in humanitarian emergencies are made according to technical criteria

Although the three decision-making steps seem logical, reality rarely allows them to be followed completely. In most crises a very small number of diseases are prioritized in vaccination campaigns (such as measles or polio). This is despite the high risk of papilloma due to high rates of sexual and gender-based violence, or the high risk of rotavirus due to poor water, sanitation and hygiene conditions. Even when a panel of experts has offered a consistent recommendation, authorities often make decisions based on other criteria.

Global initiatives for access to vaccines

Many initiatives try to cope with the high cost of vaccines

The high cost of vaccines is, of course, a major constraint. In the face of this, some global initiatives have emerged, such as Gavi (the Vaccine Alliance), the Humanitarian Mechanism, or COVAX.

Gavi is a public-private partnership created to provide more than 20 different vaccines at affordable prices to low- and middle-income countries. The Humanitarian Mechanism, however, is a collaboration between MSF, Save the Children, UNICEF and WHO. This alliance of humanitarian actors tries to negotiate reduced prices for vaccines such as pneumococcal vaccines with big pharma. Without discounts, their use by humanitarian organizations in emergencies may be impossible. Finally, COVAX was an initiative developed between 2020 and 2023 for the response to the COVID-19 pandemic. It sought to facilitate access to vaccines against this disease for low- and middle-income countries.

A global stockpile of vaccines is available for use in epidemics

Sometimes the challenge of lack of access to a sufficient number of vaccines in a country occurs, not for prevention, but for epidemic control. This is because in many fragile contexts there are insufficient vaccines for control of large infectious outbreaks.

For this reason, in 1997 WHO, UNICEF, IFRC and MSF founded the International Coordination Group on Vaccine Provision. Since then, this body has been improving its governance and accountability. It has also managed to consolidate its funding with the support of Gavi (The Vaccine Alliance). This mechanism today maintains a global emergency stockpile of meningitis, yellow fever, cholera and Ebola vaccines. This stockpile can be distributed immediately in the event of major epidemics. To date, it has distributed more than 250 million doses.

International Coordination Group for Vaccine Supply

This group, however, depends in turn on collaboration with pharmaceutical companies for the manufacture of vaccines. It also depends on UNICEF for the distribution of doses.

In addition, it collaborates with national governments (and their partners) on vaccination interventions. This includes the detection and confirmation of outbreaks, the dispatch of requests and the management of incoming vaccines. The latter starts with customs procedures for entry into the country. It continues with the maintenance of their cold chain during storage and transport domestically, and ends with the development of vaccination campaigns.

Infectious diseases

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