Immunization schedules vary by country due to local epidemiology of vaccine-preventable diseases as well as financial resources. Schedules also differ greatly between developed countries and underdeveloped countries.  In order to achieve high immunization coverage for a population it is pertinent to administer vaccines early in a child's life, specifically before a child is at risk of exposure to the disease.  High immunization coverage grants herd immunity to the population, which reduces the risk of infection for the population as a whole regardless of a single persons' immunization status.

For Individual Vaccination Fact Sheets, please visit:  http://www.immunize.org/vis/

Table 3: Immunization schedule recommended by the WHO for infants in developing countries

*OPV-1 is recommended at birth in endemic countries. In non-endemic countries OPV-1 should be given at approximately 6, 10, 14 and 18 weeks (Childinfo, 2010).

**Two doses of the Rotarix vaccine are necessary.  If the RotaTeq vaccine is used then a  third dose is necessary (Childinfo, 2010).

***Immunization against yellow fever is recommended in countries at risk for outbreaks (WHO, 2006; Childinfo, 2010).

The Expanded Program for Immunization (EPI)

In 1974 the WHO, UNICEF, and other international partners formed the Expanded Program for Immunization (EPI). EPI was created in response to the success of smallpox eradication and sought to increase childhood vaccination coverage from where it stood at program initiation, which was 5%. EPI introduced two new vaccines, poliomyelitis and measles, to the already routine immunizations of smallpox, BCG, diphtheria, tetanus, and pertussis (DPT). The program also developed widely used training materials for health workers and system managers. Today almost every country in the world has adopted the principle of a national immunization program. Through EPI, global immunization rates for six vaccine preventable diseases have increased to 79% today (UNICEF, 2010).

EPI encourages the use of complementary vertical and horizontal approaches to maximize service delivery. Vertical approaches refer to mass campaigns while horizontal approaches use primary health care facilities and outreach endeavors (Makela, 1994). Strategies to immunize children through EPI include routine vaccinations at fixed clinics or health posts, outreach and mobile clinics, and mass immunization campaigns (MIC) (Cutts, 2000). The potential efficacy of each strategy is largely situational. For example, mass immunization campaigns may be more appropriate in rural areas or areas affected by chronic conflict. In these cases, it may be unrealistic to build and maintain fixed health facilities, and as a result, access may be impeded. Although more expensive and difficult to sustain, MIC in refugee situations and during epidemics is an essential intervention to stop the spread of disease and save lives. This method has proven successful in the eradication of smallpox and the elimination of polio in the Americas (Cutts, 2000).

EPI is an important component of the Integrated Management of Childhood Illnesses (IMCI) program, which is based on the theory that children in the developing world receive more complete, quality care when service delivery combines both curative and preventive measures. Additionally, IMCI strives to strengthen the overall health system. Though this is a lofty goal, its success may translate to improvements in vaccination programs and health outcomes for children. According to IMCI, every time a child visits a health care facility, it is an opportunity to administer vaccines, as well as to inform caretakers of the value of immunization (WHO, IMCI, 2005). It has been shown that administering vaccines while a child has a minor illness does not compromise vaccine efficacy or harm the child (Makela, 1994).

Component of Effective Vaccination Programs

Five components are essential to any effective vaccination program:

1) It is important to ensure the supply and quality of vaccines through production and procurement.

2) Logistical support must be provided to ensure transport and provision of supplies as well as waste management.

3) Communication of the program to advocate and mobilize the population as well as regular programming components.

4) Active surveillance of the program to include routine reporting, case investigation and diagnostics is essential.

5) Service delivery including policy strategy and guideline development, planning and coordination at various levels, budgeting, training, supervision, and monitoring. Access is also an issue under the realm of service delivery. Access may be negatively affected by many factors including cost, distance, lacking infrastructure, health seeking behavior, or the situation of complex humanitarian emergencies (Onyango, 2005).

Monitoring and Evaluation

Effective immunization programs require routine monitoring and evaluation using key indicators to assess the impact and performance of an immunization program. Indicators collected include: the number of vaccinated children (and/or women), percentage of eligible population covered by vaccination, and incidence of the vaccine preventable disease.

Coverage data is collected at various levels of health systems in each participating country, and is then regularly reported to their own national ministry of health and to the WHO. Typically an Immunization Record Card is used to record the immunization status of each child registered at a particular health care facility. From these records, the necessary data can be ascertained, and the coverage indicators calculated. Surveys taken at national and sub-national levels are also used to collect data. There population-based methods of data collection are used for validating data obtained from those routine health information systems.

The WHO recommends two methods for determining overall population estimates of immunization coverage: EPI cluster sampling and the Lot Quality Assessment Sampling (LQAS). The cluster method, which is relatively inexpensive, involves collecting vaccination information from 7 children of a certain age, in 30 clusters of households. The LQAS method is a type of stratified sample (WHO, 2005). 

While coverage is an important indicator it is only one factor of a successful immunization program. The WHO also recommends monitoring the following aspects of immunization programs: planning, financing, surveillance, human resources, logistics and cold chain, vaccine supply, social mobilization and links with the community, outreach activities, and safety. A minimal set of core indicators should be collected in all national programs. This common set of indicators permits cross-country comparisons. Individual countries should select additional criteria that are relevant and appropriate for improving their specific programs (WHO, 2005).

Cost-Effective Program Strategies

Cost-effectiveness of immunization programs is related to delivery strategies as well as to the scale of vaccine production. The greater the number of fully immunized children per strategy per year, the lower the cost per child immunized. To increase output levels, program managers can:

• Increase the demand for services through health education and promotional activities;
• Reduce the number of missed opportunities for immunizations (for example, ensuring that families who have traveled long distances receive services, thereby avoiding the necessity to reschedule vaccination clinics, or expanding services in settings where children present themselves such as schools and during routine health care services);
• Ensure sufficient and regular supplies of essential vaccines and equipment; and
• Provide incentives to workers to increase motivation and productivity (Brenzel & Craquel, 1994).

Though cost of the vaccinations is an important consideration for governments, quality must be the primary concern. While many companies create vaccines, a fact which may drive down prices, few products actually meet international standards of both safety and efficacy. As a result, procurement of vaccinations must be completed by trained and knowledgeable teams or individuals (WHO, 2006).

Funding Vaccinations and the Global Alliance for Vaccines and Immunizations

While EPI made spectacular gains, coverage varied widely between regions and countries, and by 1998 global immunization rates had actually fallen (Cutts, 2000). In 2000, the Global Alliance for Vaccines and Immunizations (GAVI) was founded as a public-private partnership to expand and improve access to sustainable immunization services and to accelerate the introduction of new vaccines in developing countries. GAVI is a coalition of global leaders including the WHO and World Bank, UN organizations, national governments, foundations, NGOs such as UNICEF, research institutions and the pharmaceutical industry. 

They established the Vaccine Fund to make funding available for current immunization programs and to promote the introduction of new and underutilized vaccines. The Vaccine Fund focuses its resources to support the poorest countries (countries below $1,000 GNI/capita). In September 2005, the Bill and Melinda Gates Foundation pledged $750 million in support, along with European government contributions (GAVI, 2005).  This alliance has led to the development of Advanced Market Commitment (AMC). 

The AMC is a pilot project devised to assure pharmaceutical companies that if large quantities of vaccines are developed there will be a market for them to sell these vaccines in poorer countries. The focus right now is to ensure that enough pneumococcal vaccines will reach the countries that have the greatest need. Full project funding was raised by 2009.  Pharmaceutical companies are working to develop the vaccines needed that will meet WHO standards and join the new innovative plan.  Under the AMC 10 year contracts $7 will be paid per injection for the first 20% of vaccines provided then the price will decrease to $3.50 for the remainder of the contract (GAVI, 2009).

To learn more about GAVI and AMC, please visit: http://www.rockhopper.tv/GAVI/#

Cold Chain: Ensuring Quality Vaccines

The "cold chain” is a term used to describe a system for keeping and distributing vaccines in good condition. All vaccines must be stored at appropriate temperatures (2°C and 8°C) from the moment they leave the manufacturer, through shipping and storage, until they are administered ("PATH: Cold chain,” 2010). Exposure to inappropriate temperatures causes a reduction in the potency of a vaccine, rendering it ineffective. The cold chain is a continuous, uninterrupted network of refrigerators, freezers and cold boxes, organized and maintained by teams of people around the world to maintain vaccines at the specific temperature necessary to retain that vaccine's antigenic strength. 

Stock management procedures have been established so that vaccines are not stored longer than necessary at any one level of the cold chain. Keeping complete and accurate records is essential to maintaining the quality of vaccines. A stock control system comprises three steps: checking and recording details of vaccine consignments when they arrive at a storage point, checking details and conditions of vaccine stocks during the time they are kept in storage, and checking and recording details of vaccines consignments when they leave the storage point for distribution to regions, provinces, districts and, finally, patients (WHO, Vaccines-Cold Chain, 2005).

Cold Chain Monitoring

Numerous factors can impact the stability of a cold chain, including but not limited to: availability of electricity, transportation issues, government regulations, lack of training and supervision, and infrastructure collapse from wars. The following are methods to ensure quality of the cold chain:

• Upon arrival to a health clinic, vaccines are stored in refrigerators and temperatures recorded on a chart. The temperatures are monitored and recorded twice daily to ensure maintenance of a safe temperature.

• Vaccine vial monitor (VVM): The vaccine vial monitor consists of a temperature sensitive label placed on each vial that registers cumulative heat exposure for that vial. GAVI resolved that all vaccines purchased by the Vaccine Fund after 2003 will include VVM (Immunization Focus, July 2003, GAVI newsletter). 

• Freeze watch: During the freeze watch, a vial with a red liquid that bursts and stains a white placard if exposed to temp below zero for > 1 hour is packed with DTP, TT (freezing pt -6.5 C) and HB (freezing pt -0.5C) (WHO, Vaccines-cold chain, 2005).