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Next Lesson - Sepsis in Paediatrics
Core
In 1796, Edward Jenner injected fluid from a cowpox blister into a child, protecting them from smallpox and beginning the scientific advancements that now protect hundreds of millions from deadly diseases today. There are multiple different classifications of vaccines which all broadly have the same goal of producing long-term antibodies in the blood that can target a specific pathogen (disease-causing organism, such as a bacteria or virus) and prevent an infection from taking hold. See relevant immunology article for the full mechanism 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 without the possibility of infection. They lead to a long-lasting immunity with few doses. Examples include the MMR vaccine against measles, mumps, and rubella.
Inactivated vaccines contain pathogens that have been grown and then killed. Since they are not live, the vaccines are much more stable meaning they are more stable for transport and do not require refrigeration. They do not provide as long a lasting immune response as the live vaccines and so booster shots are required more regularly. The influenza vaccine is the most common example of this type of vaccine. Since the virus mutates so often this short-term immunity provides adequate cover for that winter's strain.
Toxoid vaccines contain toxins released by the pathogen that have been inactivated using formalin. They induce an immune response against the toxin, rather than the pathogen itself. Examples of this includes the Tetanus and Diphtheria vaccine.
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 Hepatitis B vaccine.
Conjugate vaccines are created when an antigen from the pathogen is linked to a polysaccharide unit, creating a greater immune response than if the antigen alone was used. An example of this is the Pneumococcal vaccine.
Vaccines have to go through a rigorous process of evaluation and testing in laboratories before moving on to first animal, then tissue trials, and finally human clinical trials, proving to be safe and effective before they are allowed to progress 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 National Institute of Biological Standards and Control oversees all production of and safety of vaccines in the UK. They provide and enforce the regulations for development, manufacturing, distribution, and monitoring of all vaccines in the UK. The Joint Committee on Vaccination and Immunisations advises the UK government on vaccine policies and which ones should be implemented nationally.
Vaccines are the most cost-effective method of saving a life, with every dollar invested in them, 16 dollars are saved in terms of avoiding healthcare costs[1] (made up of hospital treatment, health worker wages, ambulance cost) and avoiding lost wages (through either a patient becoming ill, or having to take time off to look after their children). They have eradicated smallpox, have contained polio to only 3 countries, 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 compared to that of a high-income country with 80% of those deaths occurring in Sub-Saharan Africa and Central and Southern Asia alone[2], and there are around 1.5 million vaccine-preventable deaths each year[3] as either governments or patients simply cannot afford the vaccine. Rotavirus diarrhoea and pneumococcal disease alone make up a quarter of these deaths[4]. By preventing children from becoming ill, collectively their cognitive skills, physical strength, and school performance are always improved in comparison to their peers who did suffer from these preventable illnesses.
Vaccines are not just about the individual protection they offer, but are also that of the community. 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 causes the pathogen to die out, as it cannot find a host without immunity.
Herd immunity protects patients who are unable to have the vaccine. This is commonly due to immune defects – if the patient is unable to produce antibodies against pathogens the vaccine will not give them immunity. These defects can be inherited (genetic conditions), or acquired (through iatrogenic immunosuppression).
The percentage of the population that needs to be immunised for herd immunity to develop depends on how transmissible the disease is, for example measles needs the WHO recommended 95% vaccine uptake for eradication to occur[5].
Pneumococcal vaccines have led to a vast reduction in the number of infections and correspondingly the number of antibiotics that are used to treat the infections. As a result of this, a marked slowing in the rate of pneumococcal antibiotic resistance[6] has been shown meaning that we can keep using these antibiotics for longer and in those patients where vaccines are not an option.
In the UK there is a very thorough vaccination schedule dictated by the advisory bodies that should be followed throughout childhood and when patients are older. 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 vaccination schedule for the UK
Table created by Thomas Burnell, edited by Tom Bradley. Information sourced from https://www.nhs.uk/conditions/vaccinations/nhs-vaccinations-and-when-to-have-them/
The common side effects of vaccines include feeling slightly unwell for a couple of days, and a sore arm around the injection site. This may present in children with 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. This can include emphasising that giving many vaccines at once (for example the 6-in-1 vaccine) will not overload the immune system but will reduce the amount of vaccinations needing to be given, reassurance that all vaccines have been tested rigorously, and that no ingredient in vaccines is harmful in such 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 about attendance to the Emergency Department if any symptoms of allergy present.
There are some specific circumstances where patients need extra vaccines on top of the universal set.
The influenza vaccine is offered every year to patients suffering with any chronic diseases (for example, asthma or diabetes), those who are immunosuppressed, those who have splenic dysfunction or suffer from asplenia.
Patients who have chronic kidney disease and splenic dysfunction are also offered the pneumococcal vaccination every 5 years in comparison to the standard one-off immunisation.
At-risk individuals such as health care workers, or carers of elderly or disabled people will be offered the influenza vaccine to protect themselves and those they care for. Health care workers in the UK are also encouraged to have had the MMR, BCG (preventing TB), Hepatitis B and Tetanus vaccines to help prevent the spread of these diseases to the unwell in the healthcare environment.
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 they have taken effect and to cover the cost.
If vaccines are missed, delayed or simply not given to children, they can be given at a later stage in life if requested by the patient.
The Barriers Against Vaccinations
Vaccines save lives, they are cheap, easily accessible, safe and they work. So why is it so difficult to get people to be vaccinated?
For some patients who are extremely needle-phobic or those who have had allergic reactions to vaccines or medications, it is understandable why they may dislike the thought of a vaccine. This can be worked through with reassurance, counselling, and safety precautions put in place ensuring that the same reaction would not occur. However, these groups make up a mere fraction of the number of people who will not accept a vaccine.
This phenomenon is termed Vaccine hesitancy, defined as a delay in acceptance or refusal of vaccines despite the availability of vaccination services.
Much of the outcry stems from a now discredited and disproven study conducted by British doctor Andrew Wakefield in 1996, who attempted to demonstrate that the MMR vaccine caused autism. Celebrities of that time such as Jenny McCarthy who campaigned against the vaccine used this controversial study as their evidence and brought the matter into the public eye.
The study was published in The Lancet, a generally reputable medical journal but was immediately discredited due to multiple factors: the very small sample size of 12 children and the fact that these children were specifically selected for this study (rather than selecting children at random) meant that the study was invalid. The data collected was based upon the parent’s observation and beliefs surrounding what may have caused the developmental issues in their children, rather than a clinical diagnosis made by a healthcare professional, and there were also financial conflicts of interest that contributed to the invalidation of this study.
Importantly, there was a financial conflict of interest between a lawyer who was funding the research, and was also working on a lawsuit against the vaccine companies for the parents who believed that the vaccine had given their children autism.
Multiple accredited studies testing a far greater number of children have found no link between the MMR vaccine and autism. Since the disprovement of his study, Wakefield was struck off the British Medical register, meaning he is no longer able to practice as a doctor in the UK.
Sadly, as a result of these media campaigns, a fear of vaccines was instilled in parents around the world leading to a drop in the uptake of vaccinations and a loss of herd immunity[7]. From this, outbreaks of measles have started to break out across the world and are becoming more frequent.
Discussions with concerned parents about the MMR vaccine happen daily and it is up to the medical practitioner to listen to these patients and help them to understand why they are afraid, why we give vaccines, how they work, what the benefits are, and why it is safe for their child to have in a non-judgemental manner. Remember, a judgemental approach may encourage parents to double down and refuse to vaccinate full stop.
[1] https://www.vaccinestoday.eu/stories/vaccines-save-lives-and-money/
[2] https://www.who.int/news-room/fact-sheets/detail/children-reducing-mortality
[4] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4663461/
[6] https://www.ijidonline.com/article/S1201-9712(19)30397-2/fulltext
Edited by: Dr. Maddie Swannack
Reviewed by: Dr. Thomas Burnell
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