Childhood Immunisations

1. What is a Vaccine?
   
   • Types of Vaccines
   • Vaccine Safety
2. The Benefits of Vaccines
3. The UK Vaccination Schedule
   
   • Side Effects of Vaccinations
   • Specific Additional Vaccinations
4. Barriers Against Vaccinations
   
   • The MMR Scandal (1998)
5. Resources
6. Quiz

• Vaccines are one of the most effective tools that medicine has against disease.
• They reduce infection rates and deaths, and can help to reduce antibiotic resistance (when bacteria are no longer killed by antibiotics). They have eradicated smallpox (a severe viral disease that killed millions of people) from the world. Wild polio (a viral infection that can cause paralysis) is now endemic (still spreading continuously) only in parts of Afghanistan and Pakistan.
• There are multiple different types of vaccines which are all regulated to ensure that they are safe to use.
• The UK has a thorough recommended vaccination schedule throughout childhood and into later life.
• Sadly, vaccine uptake is not as high as needed. This has led to outbreaks (sudden rises in cases) of infection, and measles is again endemic in the UK. One cause is the MMR scandal, whose false claims have since been disproven.

What is a Vaccine?

In 1796, Edward Jenner inoculated an 8-year-old boy, James Phipps, with material from cowpox sores on the hands of a dairymaid. Cowpox is a mild infection, related to smallpox, that people could catch from cows. Later that year, Jenner inoculated the boy with material from a smallpox sore, and the boy did not develop the disease. This began the scientific advances that now protect hundreds of millions of people from deadly diseases. There are several types of vaccine. They all broadly aim to produce long-term antibodies in the blood that target a specific pathogen (disease-causing organism, such as a bacterium or virus) and prevent an infection from taking hold. See relevant immunology article for the full mechanism of vaccines.

Types of Vaccines

Live Attenuated vaccines contain pathogens that are alive, but weakened (think of a bee with its stinger removed). The body responds to these weakened pathogens as it would against the full-strength pathogen, producing antibodies with a very low risk of causing disease in healthy individuals. They lead to a long-lasting immunity with few doses. However, live vaccines can cause severe infection in people with some types of severe immunosuppression (a very weakened immune system), so these people should not be given them. Examples of live vaccines include the MMR vaccine against measles, mumps (a viral infection that causes painful swelling of the salivary glands) and rubella (German measles, which can harm an unborn baby). Since January 2026, young children have been offered the MMRV vaccine instead, which also protects against varicella (chickenpox, a common viral infection that causes an itchy, blistering rash).

Inactivated vaccines contain pathogens that have been grown and then killed. Since they are not live, the vaccines are generally more stable for transport, although many still require refrigeration to maintain effectiveness. They do not provide as long a lasting immune response as the live vaccines, so booster doses (repeat doses that top up immunity) are needed more often. An example is the inactivated polio vaccine, which is part of the 6-in-1 vaccine (one injection that protects against six diseases) given to babies. The flu vaccine given to adults aged 65 and over is also inactivated. Flu viruses change often, so each year the WHO recommends which strains (types) of flu virus the vaccines should contain, and the vaccine is updated every year. Children aged 2 to 17 are usually offered a live attenuated nasal spray flu vaccine instead.

Toxoid vaccines contain toxins (poisons) released by the pathogen that have been inactivated using formalin (a solution of the chemical formaldehyde). They induce an immune response against the toxin, rather than the pathogen itself. Examples include the tetanus and diphtheria vaccines. Tetanus is a disease in which a bacterial toxin causes painful muscle spasms. Diphtheria is a bacterial infection, usually of the throat, whose toxin can damage the heart and nerves.

Subunit vaccines include only the part of the pathogen that is antigenic (i.e. the part that the immune system recognises). They are difficult to produce as it is hard to isolate one antigen, but the vaccine has a lower likelihood of adverse reactions because there is less of the pathogen. An example of this is the recombinant (made using genetically engineered cells) hepatitis B vaccine.

Conjugate vaccines link a polysaccharide antigen from the pathogen to a carrier protein. This improves the immune response and supports immunological memory (the ability to respond quickly if the same pathogen is met again), including in young children who respond poorly to unconjugated polysaccharides. An example is the pneumococcal conjugate vaccine. It protects against Streptococcus pneumoniae (the pneumococcus), a bacterium that commonly causes pneumonia, meningitis and sepsis.

Vaccine Safety

Vaccines go through a rigorous process of evaluation and testing. Testing starts in laboratories, then moves on to animal studies and finally human clinical trials. At each stage, the vaccine must be shown to be safe and effective before it can move to the next step. All of this must occur before any vaccines are allowed to be distributed amongst the population where all effects are still very closely monitored by independent organisations.

The Medicines and Healthcare products Regulatory Agency (MHRA) is the UK regulator for medicines, including vaccines. It makes sure they meet standards of safety, quality and effectiveness. It also monitors their safety once they are in use, including through the Yellow Card scheme (where suspected side effects are reported). The National Institute for Biological Standards and Control (NIBSC), an expert centre of the MHRA, independently tests each batch of vaccine before it can be supplied. The Joint Committee on Vaccination and Immunisation (JCVI) advises the UK government on vaccine policies and on which vaccines should be offered nationally.

The Benefits of Vaccines

Vaccines are one of the best health investments available. Worldwide, vaccination prevents an estimated 3.5 to 5 million deaths every year. One study of 94 low- and middle-income countries estimated that, between 2011 and 2020, every US dollar spent on vaccines would save about 16 dollars^[1]. This counted only the costs of illness avoided: healthcare costs (such as hospital treatment, health worker wages and ambulance costs) and lost wages (when patients become ill, or parents take time off to look after their children). They have eradicated smallpox, have reduced the number of countries where wild polio is endemic from more than 125 in 1988 to only 2 (Afghanistan and Pakistan), and reduced incidences of many diseases all around the world.

Children in low-income countries are far more likely to die before the age of five than children in high-income countries. In 2024, more than four in five deaths in children under five worldwide occurred in sub-Saharan Africa and Southern Asia^[2]. In 2023, more than 14.5 million children worldwide did not receive any vaccines^[3]. In 2025 the WHO put this figure at 13.5 million, pointing to a lack of access to vaccination and other health services. Pneumonia and diarrhoea (loose, watery stools) together caused about a quarter of deaths in children under five in 2013^[4]. Some of these deaths are caused by infections that vaccines can prevent, such as pneumococcus and rotavirus (a virus that commonly causes gastroenteritis in babies and young children). Children who avoid these preventable illnesses often have better cognitive skills (thinking and learning), physical strength and school performance than peers who did have them.

Vaccines protect the community as well as the individual. If a high enough percentage of the population is vaccinated against a disease, a phenomenon known as herd immunity takes place. This is a condition where most of a community are vaccinated and immune, meaning that a person who is currently infectious with the disease is unlikely to come into contact with a person who is not immune. This reduces transmission, as the pathogen is less likely to find a host without immunity.

Herd immunity protects people who cannot have a vaccine or cannot respond to it, and babies who are too young to be vaccinated. Many of these people have immune defects. If a patient cannot produce antibodies against a pathogen, the vaccine will not give them immunity. These defects can be inherited (genetic conditions) or acquired, for example through iatrogenic immunosuppression (a weakened immune system caused by medical treatment, such as chemotherapy for cancer).

The percentage of the population that needs to be immunised for herd immunity to develop depends on how transmissible the disease is. For example, to achieve and maintain measles elimination (no continuous spread within a country), the WHO recommends 95% uptake of two doses of MMR vaccine by 5 years of age^[5].

Pneumococcal vaccines have led to a large reduction in the number of infections, and so in the amount of antibiotics used to treat them. They have also greatly reduced the spread of the antibiotic-resistant strains that the vaccines target^[6]. Using fewer antibiotics helps to slow resistance. This means antibiotics keep working for longer, including for patients who cannot be protected by vaccines.

Vaccination Schedule

The UK has a detailed vaccination schedule for childhood and later life. It is based on advice from the JCVI to the UK government. Vaccines often have to be given in multiple doses, with boosters given at times to help increase the specific antibody levels in the blood to ensure that there is immunity.

Table - The routine vaccination schedule in England (as of October 2026)

Key: the 6-in-1 vaccine protects against diphtheria, tetanus, whooping cough (pertussis, a bacterial infection that causes long bouts of coughing), polio, Hib and hepatitis B. Hib is Haemophilus influenzae type b, a bacterium that can cause meningitis. MenB and MenACWY protect against meningococcal bacteria (groups B, and A, C, W and Y), which cause meningitis and sepsis. MMRV protects against measles, mumps, rubella and varicella. HPV is human papillomavirus, which can cause cancers such as cervical cancer. Shingles is a painful rash caused when the chickenpox virus becomes active again. RSV is respiratory syncytial virus, a common cause of chest infections. Children born before 2025 may follow a slightly different schedule (for example, MMR rather than MMRV). Some groups at higher risk are offered extra vaccines (see below).

Table updated in October 2026 from the original by Dr. Thomas Burnell, edited by Dr. Tom Bradley. Information sourced from https://www.nhs.uk/conditions/vaccinations/nhs-vaccinations-and-when-to-have-them/ and the UKHSA complete routine immunisation schedule

Side Effects of Vaccination

The common side effects of vaccines include feeling slightly unwell for a couple of days, and a sore arm around the injection site. In children, side effects may also include a fever, vomiting, abnormal crying, irritability and a loss of appetite (source).

It is important to address any concerns that parents or patients themselves may have about vaccination. Explain that giving several vaccines at once (for example the 6-in-1 vaccine) does not overload the immune system, and it means fewer injections. Reassure them that all vaccines have been tested rigorously. Vaccines contain no harmful ingredients: only ingredients needed to make them safer and more effective, in very small amounts (source).

Some vaccinations contain allergens such as eggs. It is therefore important to double-check with parents and patients about allergies, and to give appropriate safety netting advice, including seeking urgent medical help if there are features of anaphylaxis such as breathing difficulty, facial swelling or collapse.

Specific Additional Vaccines

There are some specific circumstances where patients need extra vaccines on top of the universal set.
The influenza vaccine is offered every year to the age groups shown in the schedule above. It is also offered every year to people in defined clinical risk groups, rather than to everyone with a long-term condition. These include people with:

• chronic respiratory disease, including asthma that needs continuous or repeated steroid treatment or has led to a hospital admission
• diabetes
• chronic heart, kidney, liver or neurological disease
• a weakened immune system (immunosuppression)
• splenic dysfunction (a spleen that does not work properly) or asplenia (no spleen).

Patients with splenic dysfunction, asplenia or some types of chronic kidney disease are offered the pneumococcal vaccination with 5-yearly boosters, because their antibody levels are likely to fall quickly. The kidney group covers chronic kidney disease stages 4 and 5, nephrotic syndrome (a kidney condition in which a lot of protein leaks into the urine), and people on dialysis (treatment that filters the blood when the kidneys fail) or with a kidney transplant. Other clinical risk groups are usually offered a one-off pneumococcal vaccination, and repeat doses are not recommended. People with asplenia or splenic dysfunction are also offered the meningococcal vaccines, MenACWY and MenB.

Healthcare and social care workers in direct contact with patients, and some carers, are offered the influenza vaccine every year to protect themselves and those they care for. Carers are eligible if they receive carer's allowance, or if they are the main carer of an elderly or disabled person whose welfare may be at risk if the carer falls ill. Healthcare workers in the UK should also be up to date with their routine vaccines, such as MMR, tetanus, diphtheria and polio. MMR is especially important because staff could pass measles or rubella to vulnerable patients. Depending on their role, healthcare workers may also need the hepatitis B vaccine (if they may have contact with patients' blood), the BCG vaccine against tuberculosis (TB) (if they may have close contact with infectious patients), and the varicella (chickenpox) vaccine if they are not immune.

Patients who are travelling outside of the UK will often need specific vaccinations depending upon where they are travelling to. It is the responsibility of the patient to organise these vaccines in enough time before their trip, so that the vaccines have taken effect. Some travel vaccines are free on the NHS, such as those against typhoid (a bacterial infection spread through contaminated food or water) and hepatitis A. Others must be paid for, such as those against rabies (a viral infection spread by animal bites or scratches) and yellow fever (a viral infection spread by mosquitoes).

If children miss vaccines or have them late, most vaccines can still be given later as catch-up doses, so parents or patients should contact their GP surgery. Some vaccines have strict age limits. For example, the first dose of rotavirus vaccine must be given before 15 weeks of age, and the second dose before 24 weeks.

Preview the Child Immunisations quiz