Vaccination schedule: how WHO and countries decide

A family doctor sees a mother who has just moved from Germany with a four-month-old baby. The booklet brought from there has vaccines, ages and intervals that do not match the schedule of the new country. The mother asks which of the two is right. The honest answer is that both can be, because each schedule results from a decision made by a committee that looked at the same science and at a different reality.

The vaccination schedule looks like a fixed table, but it is the product of a process. It starts with the assessment of the evidence on each vaccine, goes through global recommendations from the World Health Organization and ends in national committees that weigh the burden of disease, cost, logistics and local acceptance (Schaefer, 2026).

This text shows who decides, with what method, why schedules change from one country to another and what that means for the clinician who receives patients vaccinated elsewhere.

Key points

• The Strategic Advisory Group of Experts on Immunization (SAGE) has advised WHO since 1999 and publishes the basis of the global recommendations (Marti, 2024).
• Each country adapts these recommendations through a national technical advisory group, known by the acronym NITAG (Henaff, 2025).
• The efficacy and safety of a vaccine hold anywhere; the burden of disease, the cost and the capacity of the system change from country to country (Schaefer, 2026).
• The committees use the GRADE method and a structured framework that goes from evidence to recommendation (Oliver, 2024).
• The same dengue vaccine received different guidance for travelers from 18 advisory bodies in 17 countries (McGuinness, 2026).
• Different schedules can be equally correct; what matters in clinical practice is completing the schedule of the country where the person lives.

Summary

• What a vaccination schedule is and who decides it
• SAGE and the global recommendations from WHO
• The national technical groups (NITAGs)
• From data to recommendation: GRADE and the framework from evidence to decision
• Why the same evidence generates different schedules
• Cost, value, cooperation and changes in the schedule
• What this changes in clinical practice
• How NEXO helps train this reasoning
• Frequently asked questions
• Take-home messages

What a vaccination schedule is and who decides it

A vaccination schedule defines which vaccines are offered, at what age, with what intervals and for which risk groups. It includes childhood, but also adolescents, pregnant women, adults and older adults. In many countries, adult schedules are far less standardized than childhood ones and vary more between neighbors (Benedyk-Lorens, 2026).

The decision involves three layers. In the first, the regulatory agency approves the product based on efficacy, safety and manufacturing quality. In the second, WHO, advised by SAGE, publishes recommendations for global use. In the third, each country's technical committee recommends to the government how to incorporate the vaccine into the public program (Marti, 2024).

Regulatory approval answers whether the vaccine works and is safe under the conditions studied. The public health recommendation answers another question: is it worth offering it to an entire population, to whom, when and at what opportunity cost. That is why the recommendation can be more restricted than the package insert, or even go beyond it, when there is new evidence that has not yet reached the registration (Marti, 2024).

Mandatory vaccination is another layer, a political one. In the European Union and the European Economic Area, only 9 countries make any vaccination mandatory; the others work with recommendation and free offer (Benedyk-Lorens, 2026). The legal obligation changes little in the technical content of the schedule, but it changes the way it reaches families.

Why the schedule matters so much

Immunization programs are among the public health interventions with the greatest impact. The WHO Expanded Programme on Immunization, created in 1974, would have prevented about 154 million deaths in five decades, according to estimates cited in the SAGE review (Marti, 2024). This gain depends on decisions well made and maintained over time.

When vaccination falls, diseases return. Measles reappears first in crisis contexts, as shown in the text on measles when vaccination stops, and diphtheria resurges in outbreaks in several countries, as in the text on what happens when vaccination falls.

SAGE and the WHO global recommendations

SAGE was created in November 1999 as the WHO's main advisory group for vaccines and immunization. It brings together independent experts from various regions and disciplines, who declare conflicts of interest before each participation (Marti, 2024).

The technical work is prepared by thematic working groups, which review the literature, commission systematic reviews and modeling, and bring a proposal to the plenary meetings. The approved recommendations become the WHO position papers. By the 2024 revision, the WHO had published 78 of these documents on 27 vaccines (Marti, 2024).

Recommendations that go beyond the package insert

SAGE recommends based on the available evidence, even when it goes beyond what the product registration says. In 2022, it began accepting single-dose schedules of the human papillomavirus vaccine for certain ages, a recommendation outside the package insert at the time (Marti, 2024).

The fractional yellow fever vaccine is another example. In outbreak situations with vaccine shortages, SAGE allowed the use of a fraction of the usual volume to protect more people with the existing stock (Marti, 2024). The logic is public health: protect more people with what is available, accepting some uncertainty about the duration of protection.

Recommendations that change with new data

The first dengue vaccine shows that a recommendation can be revised. The 2016 position paper was changed in 2018, when new data showed a risk of severe dengue in vaccinated people without prior infection. The recommendation began to require serological screening before vaccination (Marti, 2024).

This type of revision illustrates a central idea in health decision-making: the balance between benefits and harms changes when the evidence changes, and the recommendation must follow.

From global to regional

SAGE recommendations are designed for the whole world, and therefore need to be adapted. Regional advisory groups, such as the European ETAGE, translate the global guidance to the reality of their regions before it reaches countries (Marti, 2024).

National technical groups (NITAGs)

NITAGs are committees of experts that advise each country's ministry of health on vaccines. The ACIP in the United States, STIKO in Germany and the JCVI in the United Kingdom are among the oldest and best known (Schaefer, 2026).

STIKO, for example, has between 16 and 22 members, follows a standardized operating procedure and uses an evidence-to-decision framework for each recommendation (Schaefer, 2026). The ACIP holds three regular public meetings per year and votes on recommendations that are then adopted by the Centers for Disease Control and Prevention (Oliver, 2024).

What makes a committee functional

The WHO monitors NITAGs through six process criteria: legal or administrative basis, formal terms of reference, at least five areas of expertise among the members, at least one meeting per year, agenda and documents distributed one week before meetings, and mandatory declaration of conflicts of interest (Henaff, 2025). These data are collected through the joint reporting form that countries send to the WHO and UNICEF.

Among countries with a NITAG, the proportion of committees meeting the six criteria rose from 33 out of 100 in 2012 to 77 out of 100 in 2023, with large differences between WHO regions (Henaff, 2025). The Immunization Agenda 2030 included strengthening NITAGs among its priorities.

Technical support and maturity assessment

Having a committee on paper is different from having a committee that produces good recommendations. The SIVAC initiative, started in 2008, supported the creation and strengthening of committees in 43 countries (Howard, 2018). A study in six countries, Armenia, Ghana, Indonesia, Nigeria, Senegal and Uganda, showed that NITAGs helped give transparency and legitimacy to decisions, but depended on technical secretariats with stable staff and funding (Howard, 2018).

The global NITAG network was born from this effort. At the May 2016 meeting, 35 participants from 26 countries discussed how to sustain the committees and exchange evidence assessments among them (Adjagba, 2017). The NISH platform, from 2021, gathers resources for this exchange (Henaff, 2025).

To measure quality beyond the six formal criteria, a maturity assessment tool with 7 indicators was created, covering everything from the committee's structure to the integration of recommendations into policy (Dryer, 2024). It lets the committee itself identify where it needs to improve.

From data to recommendation: GRADE and the evidence-to-decision framework

SAGE adopted the GRADE method in April 2007 to assess the certainty of evidence (Marti, 2024). GRADE classifies the body of studies for each outcome as high, moderate, low or very low certainty, considering risk of bias, inconsistency, indirect evidence, imprecision and publication bias.

The certainty of the evidence is only one part of the decision. The text on strength of recommendation and level of evidence explains why a strong recommendation can rest on moderate evidence and a weak recommendation can exist even with good-quality studies.

The domains of the framework

The evidence-to-recommendation framework organizes the discussion into domains. In the model used by ACIP, they are: the public health problem, benefits and harms, the values of the target population, resource use, acceptability, feasibility and equity (Oliver, 2024). Each domain receives an explicit judgment, recorded in a public document.

The result is a strong or conditional recommendation at SAGE (Marti, 2024). At ACIP, the possible votes are recommend, recommend with shared clinical decision-making or do not recommend (Oliver, 2024). The shared decision-making option brings public policy closer to the clinic, as discussed in the text on shared decision-making with the patient.

Tools for smaller committees

Building a framework like this requires systematic reviews, models and trained staff. To support committees with few resources, an evidence-to-recommendation kit was developed along with an online course, used by committees in more than 30 countries (Hadler, 2024). The idea is that each committee can reuse global reviews and focus on local data.

The quality of reviews also varies

The weak point of many frameworks is the systematic review that feeds them. An assessment of 120 reviews on vaccination interventions, using the AMSTAR 2 tool, classified 110 of them as critically low confidence (Pilic, 2026). The authors suggest that committees assess the methodological quality of reviews before using them, instead of accepting the systematic review label as a guarantee.

Why the same evidence leads to different schedules

The clearest explanation comes from an analysis of national recommendations in Europe. The authors separate two types of evidence. Context-independent evidence includes efficacy, immunogenicity and safety, which hold in any country. Context-dependent evidence includes local epidemiology, cost-effectiveness, logistics, acceptance and health system priorities (Schaefer, 2026).

Two countries with the same meta-analysis on a vaccine can reach different conclusions because the disease has a different incidence, because the negotiated price is different or because the health system has more or less capacity to give the vaccine at the right age. The authors' summary is direct: same clinical evidence, different conclusions (Schaefer, 2026).

Epidemiology changes the decision

The local incidence of a disease changes the absolute benefit of the vaccine. This reasoning is the same as that of the base rate in diagnosis: the same test yields different results in populations with different prevalences, and the same vaccine prevents more cases where the disease is more common.

Dengue is a clear example. A survey of 18 advisory bodies in 17 countries, 12 of them without endemic dengue, compared guidance on the TAK-003 vaccine for travelers. Eligibility criteria, indications and how to administer it varied, and the guidance was generally more restrictive than the label, although some bodies were less restrictive (McGuinness, 2026). The traveler's risk depends on the destination, the duration of the trip and prior infection, as discussed in the text on geography and the probability of disease in the traveler.

The available product and the history of the program

Pertussis shows how the history of each program matters. WHO advises that countries using whole-cell vaccine in the primary schedule keep that vaccine, because of its longer-lasting protection; the acellular vaccine causes far fewer reactions, but protection drops sooner (Fal, 2026). Poland is the only country in the European Union and the European Economic Area that still uses whole cells in the infant primary schedule (Fal, 2026) The Polish debate about a possible switch involves duration of protection, trust, cost and supply security (Fal, 2026).

Respiratory syncytial virus offers another recent example. With a maternal vaccine and monoclonal antibodies available, STIKO recommended in 2024 the long-acting antibody for all infants in their first season and did not recommend the maternal vaccine (Schaefer, 2026). Other countries chose differently, as the text on three products and three strategies shows.

Examples of decisions and what weighed in each one

The table gathers examples described in the sources. It shows that the design of each schedule results from an explicit judgment about context, and not only from a reading of efficacy.

Decision	Who decided	Common evidence	Context factor that weighed
Remove meningococcal C vaccine from infants and offer MenACWY to adolescents (2025)	STIKO, Germany	Efficacy of conjugate vaccines	Change in epidemiology by serogroup and age (Schaefer, 2026)
Long-acting antibody against RSV for infants, without maternal vaccine (2024)	STIKO, Germany	Trials of both products	Coverage of all infants and logistics (Schaefer, 2026)
Zoster vaccine from age 60 (2018)	STIKO, Germany	Efficacy of the recombinant vaccine	Disease burden by age and cost (Schaefer, 2026)
Rotavirus from 6 weeks of age (2013)	STIKO, Germany	Efficacy and safety	Age window and risk of intussusception (Schaefer, 2026)
Dengue with prior serological screening (2018)	SAGE, WHO	Long-term data from the first vaccine	Risk in seronegative people (Marti, 2024)
TAK-003 for travelers, generally with stricter rules than the label	18 bodies in 17 countries	Same clinical trial	Destination, traveler profile, prior infection (McGuinness, 2026)
Keep whole cells against pertussis in infants	Poland	Duration of protection of each vaccine	History of the program (Fal, 2026)
Covid-19 vaccines with 24 votes in 35 meetings (2020 to 2023)	ACIP, United States	Data that changed every month	Variants, supply and risk groups (Oliver, 2024)

The German examples appear in detail because the European analysis describes them step by step. They serve to show the method; another country's choice, with another epidemiology, can be different and equally defensible (Schaefer, 2026).

Cost, value, cooperation and changes in the schedule

Resource use is one of the domains of the framework, and perhaps the one that most separates rich countries from low- and middle-income countries. The same vaccine can be cost-effective in one system and unviable in another, depending on price, budget and the other priorities in dispute.

WHO proposed assessing the full value of vaccines, known as FVVA. It broadens the analysis beyond cost per case avoided and includes wider economic and social effects, such as productivity, equity, reduced antimicrobial resistance and health security (Hutubessy, 2023). The goal is to give governments and funders a more complete basis for deciding to invest in a vaccine.

This view is similar to that of quaternary prevention: a preventive intervention also has costs, adverse effects and opportunity cost, and the decision must measure this honestly.

Cooperation without losing the national decision

In Europe, the European Centre for Disease Prevention and Control can issue non-binding recommendations on vaccines since 2022. Collaboration between European NITAGs has existed since 2018, and joint clinical assessment of health technologies should include vaccines from 2030 (Schaefer, 2026).

The authors of the European analysis argue for dividing the work on context-independent evidence, such as efficacy and safety reviews, and keeping the judgment of context-dependent evidence in each country's hands (Schaefer, 2026). This avoids redoing the same review in several places without taking from committees the decision that only they can make.

When the schedule changes

Calendars change for several reasons: a new vaccine arrives, the epidemiology changes, a safety data point appears, the price falls or the program gains the capacity to administer a more complex vaccine. Every change goes through the same evaluation process, with the advantage that the committee already knows the local context.

The covid-19 pandemic tested this process to the extreme. Between 2020 and 2023, ACIP held 35 meetings and 24 votes on covid-19 vaccines, with data that changed with the variants and with product supply (Oliver, 2024). The structured framework allowed recommendations to be reviewed quickly without abandoning transparency.

Crisis situations also test a country's capacity to decide without relying only on WHO. The recent experience with pandemics, discussed in what recent history teaches, showed the value of having decision processes defined before the emergency, with transparency rules already known (Oliver, 2024).

What this changes in clinical practice

For the clinician, understanding the process helps in three frequent situations. The first is the patient who arrives from another country with a different schedule. The general rule is to use what was administered, without starting over, and complete according to the calendar of the country where the person now lives. Differences between calendars rarely mean that one of them is wrong.

The second situation is the patient who reads about a foreign recommendation and asks why it does not apply here. The answer involves context-dependent evidence: the disease may have a different frequency, the product may not be available or the local committee may have made a different balance between cost and benefit (Schaefer, 2026). Explaining this increases confidence in the calendar instead of reducing it.

The third is the patient with several chronic conditions, who receives guidance from various specialties. The text on when guidelines add up shows how to prioritize. In vaccination, indications by risk group are usually reviewed in consultations such as COPD follow-up, described in initial treatment and follow-up.

Dealing with uncertainty

Some recommendations are conditional because the evidence is still limited or because the balance depends on each person's values. In these cases, the clinical conversation weighs more. The strategies for deciding without certainty also apply here: make explicit what is known, what remains unknown and what happens with each choice.

Knowing where each recommendation comes from also helps to recognize when it changes. A calendar is a living document, revised every year in many countries, and the clinician who follows the national committee's decisions anticipates patients' questions.

How NEXO helps train this reasoning

In NEXO, the case of the day is fictional, with a real clinical presentation and up to six progressive clues, and you propose the diagnosis by searching for the ICD-10 code. Many cases of vaccine-preventable diseases depend on asking about vaccination history and the patient's country of origin.

The limits of use of the game are described on the NEXO Economy page. If you research teaching of clinical reasoning, the page for Researchers explains how to get in touch. Professionals who write or review cases find information in Curator and in Creators, and institutions can learn about the proposal on the partnerships page. To train searching for the code, see how the ICD-10 code is built.

Frequently asked questions

Who decides a country's vaccination calendar?

The government, based on the recommendation of a national technical advisory group, the NITAG. This committee adapts WHO global guidance to the local reality (Henaff, 2025).

What is SAGE?

It is the group of independent experts that has advised WHO on vaccines since 1999. Its recommendations give rise to WHO position papers (Marti, 2024).

Why is my country's calendar different from another's?

Because vaccine efficacy is the same, but disease frequency, cost, logistics and acceptance change. Each committee weighs these factors for its context (Schaefer, 2026).

Can a recommendation differ from the package insert?

It can. SAGE has already recommended schedules outside the label, such as the single-dose HPV regimen in 2022, and many bodies were more restrictive than the label in their guidance to travellers on the TAK-003 dengue vaccine (Marti, 2024; McGuinness, 2026).

What method do the committees use to decide?

Most use GRADE to assess the certainty of the evidence and a structured framework that includes benefits, harms, values, resources, acceptability, feasibility and equity (Oliver, 2024).

What should be done with a patient vaccinated in another country?

Build on the vaccines already given and complete the schedule according to the calendar of the country where the person lives, consulting the local rules on intervals and on catching up on delays.

Do systematic reviews guarantee good recommendations?

They guarantee little on their own. In an assessment of 120 reviews on vaccination, 110 had critically low confidence by the AMSTAR 2 tool (Pilic, 2026).

Take-home messages

• The vaccination schedule is the product of a decision process, not a fixed table.
• SAGE advises WHO, and each country decides through its national technical committee.
• Efficacy and safety hold everywhere; disease burden, cost and logistics change from country to country.
• GRADE and the evidence-to-recommendation framework make the judgment explicit and auditable.
• Recommendations can be more restrictive or broader than the label, and they change with new data.
• Different schedules can be equally correct; in clinical practice, the schedule of the country where the person lives is completed.
• The quality of the reviews that feed the decision must be assessed, not presumed.

Play the case of the day on NEXO.

References

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