Childhood vaccinations: the core schedule

Newborn · Vaccines · Reviewed 18 June 2026 · All articles

Vaccines are one of the most powerful tools in child health. The World Health Organisation estimates that immunisation prevents between 3.5 and 5 million deaths every year across all age groups, and a large share of those lives saved are children under five. Understanding when vaccines are given, what they protect against, and why the timing is designed the way it is can help parents feel confident at each appointment rather than anxious.

This guide draws on recommendations from the WHO, the NHS, the CDC, and the American Academy of Pediatrics (AAP). Individual countries adapt these core recommendations into their own national schedules, so the exact timing and combination of doses your child receives may vary slightly. Always follow the schedule provided by your doctor or healthcare service. This article is informational only and does not replace medical advice.

Why vaccine timing matters

Vaccine schedules are not arbitrary. Researchers and public health bodies spend years studying the optimal age at which each vaccine produces the strongest immune response and at which children face the greatest disease risk. Several principles guide the design of every core schedule.

First, maternal immunity fades. Babies are born with antibodies passed across the placenta during pregnancy. This passive protection is valuable, but it is temporary. For most diseases, maternal antibodies drop to non-protective levels within a few months. The schedule is designed to begin building the baby's own immunity before that window closes.

Second, some pathogens are most dangerous in infancy. Pertussis (whooping cough) can be fatal in very young babies before they have completed their primary course. This is why the first dose of a pertussis-containing vaccine is given at around six to eight weeks of age in most national schedules. Similarly, Haemophilus influenzae type b (Hib) disease, which can cause meningitis and epiglottitis, is most severe in children under two.

Third, some vaccines require multiple doses to build lasting immunity. A single dose of the hepatitis B vaccine does not produce a reliably durable antibody response. Three doses, spaced weeks apart, are required to prime and then consolidate the immune memory needed for long-term protection. The CDC and WHO both specify three-dose series for this reason.

Fourth, booster doses are necessary because immunity can wane over time. The diphtheria, tetanus, and pertussis (DTP) vaccines given in infancy are followed by boosters in toddlerhood and again at school age in many countries to maintain herd-level protection throughout the community.

Core vaccines in the first year of life

While exact scheduling varies by country, there is substantial global consensus on which vaccines belong in the first twelve months. The following reflect the WHO's recommended vaccination schedule and are present in some form in the UK, US, European, and many other national programmes.

Hepatitis B (HepB). The WHO recommends that the first dose be given within 24 hours of birth wherever possible, particularly in settings with a higher prevalence of chronic hepatitis B infection. This birth dose is then followed by two or three further doses as part of combination vaccines. Hepatitis B can be transmitted from mother to baby during birth and can lead to chronic liver disease or liver cancer decades later. Early vaccination interrupts this route of transmission.

DTaP or DTP (diphtheria, tetanus, pertussis). This combination is given as a series starting at around six to eight weeks of age, with subsequent doses at two-month intervals during infancy. The acellular pertussis formulation (DTaP) used in many high-income countries is associated with fewer injection-site reactions than the whole-cell version (DTwP) while providing equivalent protection against three potentially severe bacterial diseases.

Hib (Haemophilus influenzae type b). Hib bacteria were the leading cause of bacterial meningitis in young children before the introduction of the Hib vaccine. The WHO recommends three primary doses in infancy, often combined into a hexavalent vaccine alongside DTP, hepatitis B, and inactivated polio vaccine (IPV). Since widespread adoption of Hib vaccination, invasive Hib disease has fallen by more than 90 percent in countries with high coverage.

IPV (inactivated polio vaccine). Polio can cause permanent paralysis, but global eradication is within reach thanks to sustained vaccination programmes. IPV is given as part of the primary infant series in countries that have eliminated wild poliovirus. Oral polio vaccine (OPV) is still used in some settings and is central to the global eradication effort.

Pneumococcal conjugate vaccine (PCV). Streptococcus pneumoniae bacteria cause pneumonia, meningitis, and blood infections. The conjugate vaccine generates a strong immune response even in very young infants and is recommended by both the NHS and the CDC. Two or three primary doses in infancy, followed by a booster in the second year of life, provide long-term protection.

Rotavirus vaccine. Rotavirus is the most common cause of severe diarrhoea and vomiting in infants worldwide. Before vaccination was available, it was responsible for hundreds of thousands of deaths per year in low-income settings. The oral rotavirus vaccine is given from around six weeks of age. It cannot be given after 32 weeks because the small theoretical risk of intussusception (a bowel problem) increases if the vaccine is given in older infants.

MenB and MenC/MenACWY (meningococcal vaccines). Meningococcal bacteria cause bacterial meningitis and septicaemia, which can be rapidly fatal. Different serogroups predominate in different regions, and national schedules reflect local epidemiology. The NHS, for example, includes meningococcal B vaccine from eight weeks of age because serogroup B is the commonest cause of bacterial meningitis in the UK.

Vaccines introduced in the second year of life

The period from twelve to twenty-four months is another active phase on most national schedules. Several vaccines cannot be given before twelve months because the immune response is unreliable in very young infants, or because maternal antibodies interfere with the vaccine's effectiveness.

MMR (measles, mumps, rubella). The first dose of MMR is given at around twelve months in most countries. A second dose follows at around three to five years. Two doses provide immunity in approximately 97 percent of recipients against measles, which the WHO describes as one of the most contagious infectious diseases known to science. Measles can cause severe complications including pneumonia and encephalitis, and outbreaks occur wherever vaccination coverage falls below the threshold needed for herd immunity.

Varicella (chickenpox). The varicella vaccine is recommended by the AAP and CDC at twelve to fifteen months, with a second dose at four to six years. It is not yet universally included in European national schedules, though many countries have introduced it. Chickenpox is usually mild but can cause serious complications in neonates, pregnant women, immunocompromised individuals, and occasionally in healthy children.

Hepatitis A. The CDC recommends two doses of hepatitis A vaccine starting at twelve months. Hepatitis A spreads through contaminated food and water and can cause prolonged illness. Vaccination has dramatically reduced hepatitis A incidence in countries with universal childhood programmes.

Booster doses. Most children receive boosters of DTP, Hib, polio, and pneumococcal vaccine during their second year. These boost the antibody levels established by the infant primary series and extend protection through the toddler years when social contact and disease exposure increase.

Common side effects and what to expect

The vast majority of vaccine reactions are mild, short-lived, and are signs that the immune system is responding. According to the NHS and CDC, common side effects include soreness or redness at the injection site, mild fever, irritability, and brief fussiness. These typically resolve within one to two days.

Mild fever after vaccination does not require treatment unless your baby is uncomfortable. If you do want to use a pain reliever, follow your pharmacist's or doctor's guidance on age-appropriate dosing of paracetamol (acetaminophen). The NHS specifically advises that ibuprofen should not be given to babies under three months of age.

Serious allergic reactions to vaccines are extremely rare. The NHS estimates the frequency at approximately one in a million doses. Vaccination appointments are designed to allow observation for a short period afterwards so that any early signs of a reaction can be managed immediately by trained healthcare staff.

If your baby develops a high fever (above 38 degrees Celsius in a baby under three months, or above 39 degrees Celsius in an older infant), seems unusually pale or limp, or you are worried for any reason after a vaccination, contact your doctor or seek medical attention promptly. Trust your instincts as a parent.

Frequently asked questions

Why do babies need so many vaccines in the first year?

Babies are born with some passive immunity from their mother, but this wanes within a few months. Their own immune systems are still maturing. The first year of life is when children are most vulnerable to certain serious infections, so health authorities schedule vaccines early to build protection before exposure risk becomes highest.

Is it safe to give multiple vaccines at the same visit?

Yes. According to the WHO and AAP, giving several vaccines at the same appointment is safe and does not overwhelm a baby's immune system. Combination vaccines, such as the hexavalent vaccine covering six diseases in one injection, have been specifically developed to reduce the number of injections while maintaining full protection.

What should I do if my baby misses a scheduled vaccine?

Contact your family doctor or paediatrician as soon as you notice the gap. Most national schedules include catch-up guidance, and missing a dose does not usually mean restarting a series from scratch. The sooner the missed dose is given, the sooner protection is restored. Your doctor can calculate the correct interval.

Can my baby have vaccines if they have a mild cold?

In most cases, yes. NHS and CDC guidance states that a minor illness such as a mild cold or low-grade fever is not a reason to postpone vaccination. If your baby has a higher fever or a more serious illness, discuss the timing with your doctor, who may recommend waiting a short period before vaccinating.

Do vaccines cause the diseases they protect against?

No. Inactivated and subunit vaccines contain killed or partial components of a pathogen and cannot cause the disease. Live-attenuated vaccines use a weakened form of the virus; they very rarely cause a mild, short-lived reaction in healthy children, but this is not the same as the disease itself. The WHO and AAP both confirm that the protective benefits of vaccination far outweigh these small risks.

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