CONTENT ON VACCINE SAFETY
HEALTH WORKERS
Why vaccinate?
Without vaccines, we are at risk of serious illness and disability from diseases like measles, meningitis, pneumonia, tetanus and polio. Many of these diseases can be life-threatening. WHO estimates that childhood vaccines alone save over 4 million lives every year.
Although some diseases may have become uncommon, the germs that cause them continue to circulate in some or all parts of the world. In today’s world, infectious diseases can easily cross borders, and infect anyone who is not protected.
Two key reasons to get vaccinated are to protect ourselves and to protect those around us. Because not everyone can be vaccinated – including very young babies, those who are seriously ill or have certain allergies – they depend on others being vaccinated to ensure they are also safe from vaccine-preventable diseases.
Development of a vaccine
Most vaccines have been in use for decades, with millions of people receiving them safely every year. As with all medicines, every vaccine must go through extensive and rigorous testing to ensure it is safe before it can be introduced in a country’s vaccine programme.
Each vaccine under development must first undergo screenings and evaluations to determine which antigen should be used to invoke an immune response. This preclinical phase is done without testing on humans. An experimental vaccine is first tested in animals to evaluate its safety and potential to prevent disease.
If the vaccine triggers an immune response, it is then tested in human clinical trials in three phases.
When the results of all these clinical trials are available, a series of steps is required, including reviews of efficacy and safety for regulatory and public health policy approvals. Officials in each country closely review the study data and decide whether to authorize the vaccine for use. A vaccine must be proven to be safe and effective across a broad population before it will be approved and introduced into a national immunization programme. The bar for vaccine safety and efficacy is extremely high, recognizing that vaccines are given to people who are otherwise healthy and specifically free from the illness.
Further monitoring takes place in an ongoing way after the vaccine is introduced. There are systems to monitor the safety and effectiveness of all vaccines. This enables scientists to keep track of vaccine impact and safety even as they are used in a large number of people, over a long time frame. These data are used to adjust the policies for vaccine use to optimize their impact, and they also allow the vaccine to be safely tracked throughout its use.
Once a vaccine is in use, it must be continuously monitored to make sure it continues to be safe.
https://www.who.int/news-room/feature-stories/detail/how-are-vaccines-developed
Herd immunity
‘Herd immunity’, also known as ‘population immunity’, is the indirect protection from an infectious disease that happens when a population is immune either through vaccination or immunity developed through previous infection. WHO supports achieving ‘herd immunity’ through vaccination, not by allowing a disease to spread through any segment of the population, as this would result in unnecessary cases and deaths.
Usefulness of vaccines
Vaccination is the most important thing we can do to protect ourselves and our children against ill health. WHO estimates that childhood vaccines alone save over 4 million lives every year.
Since vaccines were introduced in the world, diseases like smallpox, polio and tetanus that used to kill or disable millions of people are either gone or seen very rarely.
Other diseases like measles and diphtheria have been reduced by up to 99.9% since their vaccines were introduced.
However, if people stop having vaccines, it’s possible for infectious diseases to quickly spread again.
https://www.nhs.uk/conditions/vaccinations/why-vaccination-is-safe-and-important/
Effectiveness of vaccines
Vaccine effectiveness is a measure of how well vaccines work in the real world. Clinical trials include a wide range of people – a broad age range, both sexes, different ethnicities and those with known medical conditions – but they cannot be a perfect representation of the whole population. The efficacy seen in clinical trials applies to specific outcomes in a clinical trial . Effectiveness is measured by observing how well the vaccines work to protect communities as a whole. Effectiveness in the real world can differ from the efficacy measured in a trial, because we can’t predict exactly how effective vaccination will be for a much bigger and more variable population getting vaccinated in more real life conditions.
WHO estimates that childhood vaccines alone save over 4 million lives every year.
Since vaccines were introduced in the world, diseases like smallpox, polio and tetanus that used to kill or disable millions of people are either gone or seen very rarely.
Other diseases like measles and diphtheria have been reduced by up to 99.9% since their vaccines were introduced.
https://www.who.int/news-room/feature-stories/detail/vaccine-efficacy-effectiveness-and-protection
https://www.nhs.uk/conditions/vaccinations/why-vaccination-is-safe-and-important/
Vaccine safety
- Measles-mumps-rubella and autism vaccine?There is no evidence of any link between vaccines and autism or autistic disorders. This has been demonstrated in many studies, conducted across very large populations. The 1998 study which raised concerns about a possible link between measles-mumps-rubella (MMR) vaccine and autism was later found to be seriously flawed and fraudulent. The paper was subsequently retracted by the journal that published it, and the doctor that published it lost his medical license. Unfortunately, its publication created fear that led to dropping immunization rates in some countries, and subsequent outbreaks of these diseases. We must all ensure we are taking steps to share only credible, scientific information on vaccines, and the diseases they prevent. https://www.who.int/news-room/questions-and-answers/item/vaccines-and-immunization-what-is-vaccination
- Vaccines and autism risks?There is no evidence of any link between vaccines and autism or autistic disorders. This has been demonstrated in many studies, conducted across very large populations. The 1998 study which raised concerns about a possible link between measles-mumps-rubella (MMR) vaccine and autism was later found to be seriously flawed and fraudulent. The paper was subsequently retracted by the journal that published it, and the doctor that published it lost his medical license. Unfortunately, its publication created fear that led to dropping immunization rates in some countries, and subsequent outbreaks of these diseases. We must all ensure we are taking steps to share only credible, scientific information on vaccines, and the diseases they prevent. https://www.who.int/news-room/questions-and-answers/item/vaccines-and-immunization-what-is-vaccination
Aluminum in Vaccines
Aluminum is a metal naturally found in air, food, and water. Small amounts of aluminum salts such as aluminum hydroxide and aluminum potassium sulphate are used as adjuvants in vaccines to help the body produce a stronger immune response against the microorganism in the vaccine. Adjuvants are components that are added to make the vaccine work more effectively. However, adjuvanted vaccines tend to cause more local reactions like injection site pain, swelling and systemic reactions live fever, chills compared to vaccines without adjuvants. Scientific studies have shown that the amount of aluminum contained in vaccines is low thus does not cause harm to the body. Examples of vaccines that contain aluminum adjuvants include Diphteria-Tetanus-Pertussis vaccines (DTaP), Hepatitis B vaccine (Recombivax), Hepatitis A vaccine (Havrix), and HPV (Gardasil 9) (1).
CDC. Adjuvants and vaccines. 2022. Accessed 14/3/22; Available from: https://www.cdc.gov/vaccinesafety/concerns/adjuvants.html
Vaccine Contraindications
There are two general contraindications to all vaccines which include I) Anaphylaxis reaction to a previous dose of the vaccine II) Anaphylaxis reaction to any component of the vaccine. Anaphylaxis reaction is a serious life-threatening allergic reaction that affects various parts of the body. Symptoms include difficulty in breathing, swelling of the upper airway, abdominal pain, rashes etc. (2,3)
Live vaccines e.g., Measle, Mumps and Rubella (MMR), Bacille Calmette–Guérin (BCG), varicella, yellow fever, rotavirus, and oral typhoid vaccine should not be given to people who are severely immunocompromised as this can lead to vaccine-related disease. Examples of immunocompromised individuals include people on immunosuppressive therapy (treated with corticosteroids, disease modifying anti-rheumatic drugs), solid organ or hematopoietic stem cell transplant patients, HIV patients, congenital immunodeficiency, aplastic anemia, cancer patients receiving chemotherapy or radiotherapy (4).
https://www.health.nsw.gov.au/Infectious/covid-19/vaccine/Pages/management-of-anaphylaxis.aspx
GENERAL POPULATION
Vaccines are safe. NAFDAC ensures that vaccines have passed through the necessary processes before they are approved for use therefore approved vaccines are as safe as possible. This is further confirmed by the millions of people especially children who safely take vaccines every year. Some people may experience side effects which are mostly mild and not long-lasting. Most common side effects include a mild fever, soreness and pain at the site of injection and being irritable.
Yes, vaccines work. Infectious diseases like measles, polio, chicken pox, yellow fever etc. that once disabled or killed many children, and adults are now preventable with vaccines.
When a disease-causing organism (pathogen) infects the body, our body’s defenses, called the immune system, are triggered to produce antibodies that attack the pathogen to destroy or overcome it. Each antibody recognizes a part of a pathogen called an antigen, it will only recognize and fight a specific antigen. The immune system will also produce cells that remember the antigen the next time the person is exposed to it and so respond faster to produce antibodies to protect against the disease. Vaccines contain weakened or inactive parts of a particular organism (antigen) that trigger an immune response within the body. This weakened version will not cause the disease in the person receiving the vaccine, but it will prompt their immune system to respond much as it would have on its first reaction to the actual pathogen. For further reading https://www.who.int/news-room/feature-stories/detail/how-do-vaccines-work?adgroupsurvey={adgroupsurvey}&gclid=Cj0KCQjwkt6aBhDKARIsAAyeLJ0YSspL8vKDd6mOWS3tU1OBLo5BAHqcEUwuErenb_6yuFAnuosh2UkaAjXXEALw_wcB
Vaccines contain weakened or inactive parts of a particular organism (antigen) that triggers an immune response within the body. Newer vaccines contain the blueprint for producing antigens rather than the antigen itself. Vaccines may also contain multiple other ingredients called excipients. These may be added to vaccines to enhance the immune response (Eg. aluminium salts), to act as preservatives (e.g. thiomersal, phenol derivatives). Some excipients known as stabilizers are added to maintain the stability and effectiveness of vaccines during storage.
Vaccines are manufactured in countries that have vaccine manufacturing companies that have capacity to provide the stringent conditions under which vaccines can be developed. In addition, these countries have National Regulatory Authorities(NRA) that have attained a certain level of maturity to provide necessary oversight for the vaccine manufacturing process. The WHO plays an oversight role in assessing both the manufacturing companies and the NRAs for this function. List of vaccine producing countries can be seen here https://www.who.int/initiatives/who-listed-authority-reg-authorities/list-of-vaccine-prod-countries) Currently, the African Vaccine manufacturing initiative is working to promote the establishment of sustainable human vaccine manufacturing capacity in Africa (read more at https://www.avmi-africa.org/)
Some preservative chemicals (e.g. thiomersal, phenol derivatives) are added to subunit or killed vaccines to inactivate viruses, detoxify bacterial toxins, and prevent serious secondary infections in multi-dose vials as a result of bacterial or fungal contamination.
Stabilizers such as Magnesium Chloride (MgCl2), Magnesium Sulphate (MgSO4), lactose- sorbitol and sorbitol gelatine are used to help the vaccine maintain its effectiveness during storage.
Every day, the body is exposed to and fights off various pathogens. These pathogens have parts called antigens that trigger the immune system to produce antibodies that fight off the infection.
Vaccines contain weakened or inactive parts of a particular organism which act as antigens to trigger the body’s immune system in much the same way as occurs naturally. Therefore, even if a person takes several vaccines in one day, they will not overload the immune system.
Vaccines do not make us sick. Vaccines typically contain weakened or killed forms of the disease causing organism or its other component which stimulate an immune response without causing disease. People may experience side effects to vaccines that may be mistaken for symptoms of a disease.
Vaccines are generally safe. Some people may experience mild side effects which are treatable and resolve within a short period. Rarely people may experience severe reactions such as severe allergic reactions. The medical teams at vaccination facilities are trained to recognize and treat these kinds of reactions when they occur.
Most vaccine-induced reactions are non- serious and transient, most frequently being mild fever (<38o C), soreness and pain at the injection site. Severe and serious adverse events are extremely rare and may include, high fever, convulsions, sepsis, abscess, and anaphylactic reactions. Vaccines are continually monitored for safety, to detect rare adverse events.
NAFDAC has deployed diverse platforms for reporting of Adverse Drug Reactions as well as Adverse Event Following Immunisation (AEFI). ADRS and AEFI can be reported using the following:
- Med Safety App
- E-reporting portal (https://primaryreporting.who-umc.org/NG). Can also be accessed from the NAFDAC website
- NAFDAC offices nationwide.
- By email to Pharmacovigilance@nafdac.gov.ng
In addition, AEFI may be reported at the vaccination facilities. The National Primary Healthcare development Agency has deployed the DHIS2 tool for facility based reporting.
Some people have had concerns that Autism Spectrum Disorder (ASD) might be linked to the vaccines children receive, but studies have shown that there is no link between receiving vaccines and developing ASD. The National Academy of Medicine, formerly known as Institute of Medicine, reviewed the safety of 8 vaccines to children and adults. The review found that with rare exceptions, these vaccines are very safe.
Source: Adverse Effects of Vaccines: Evidence and Causality external icon
A CDC study published in 2013 added to the research showing that vaccines do not cause ASD. The study focused on the number of antigens given during the first two years of life. Antigens are substances in vaccines that cause the body’s immune system to produce disease-fighting antibodies. The results showed that the total amount of antigen from vaccines received was the same between children with ASD and those that did not have ASD.
Babies receive multiple vaccines when they are between 2 to 4 months old. This age range is also the peak age for sudden infant death syndrome (SIDS). The timing of the 2 month and 4-month shots and SIDS has led some people to question whether they might be related. However, studies have found that vaccines do not cause and are not linked to SIDS. Multiple research studies and safety reviews have looked at possible links between vaccines and SIDS. The evidence accumulated over many years do not show any links between childhood immunization and SIDS.
https://www.cdc.gov/vaccinesafety/concerns/sids.html
https://www.cdc.gov/vaccinesafety/concerns/autism.html
When someone is vaccinated, they are very likely to be protected against the targeted disease. But not everyone can be vaccinated. People with underlying health conditions that weaken their immune systems (such as cancer or HIV) or who have severe allergies to some vaccine components may not be able to get vaccinated with certain vaccines. These people can still be protected if they live in and amongst others who are vaccinated. When a lot of people in a community are vaccinated the pathogen has a hard time circulating because most of the people it encounters are immune. So the more others are vaccinated, the less likely people who are unable to vaccinate will be exposed to the harmful pathogens. This is called herd immunity.
Vaccinating not only protects yourself, but also protects those in the community who are unable to be vaccinated. If you are able to, get vaccinated.
Immunization schedule is safe and effective at protecting your child. It’s based on how your child’s immune system responds to vaccines at various ages, and how likely your child is to be exposed to a particular disease.
Delaying vaccines could leave your child vulnerable to disease when she’s most likely to have serious complications.
Young babies are at highest risk of serious disease complications. For example, for you, whooping cough may mean a lingering cough for several weeks, but it can be very serious—even deadly—for babies less than a year old. If you delay vaccinations, your baby could be exposed to diseases like whooping cough when she is most likely to have serious complications.
https://www.cdc.gov/vaccinesafety/concerns/multiple-vaccines-immunity.html
For some vaccines, the active ingredient is grown in laboratories on cultures that contain human cells. Some viruses, such as chickenpox (varicella), grow much better in human cells. After they are grown, the viruses are purified several times to remove the cell culture material. This makes it unlikely that any human material remains in the final vaccine.
https://www.who.int/news-room/questions-and-answers/item/vaccines-and-immunization-vaccine-safety
Scientific evidence shows that giving several vaccines at the same time has no negative effect. Children are exposed to several hundred foreign substances that trigger an immune response every day. The simple act of eating food introduces new germs into the body, and numerous bacteria live in the mouth and nose.
When a combined vaccination is possible (e.g. for diphtheria, pertussis and tetanus), this means fewer injections and reduces discomfort for the child. It also means that your child is getting the right vaccine at the right time, to avoid the risk of contracting a potentially deadly disease.
Giving a child several vaccines during the same visit offers two advantages.
First, children should be given their vaccines as quickly as possible to give them protection during the vulnerable early months of their lives. Second, giving several shots at the same time means fewer office visits. This saves parents time and money, and can be less traumatic for the child.
https://www.cdc.gov/vaccinesafety/concerns/multiple-vaccines-immunity.html
Vaccination is safe and side effects from a vaccine are usually minor and temporary, such as a sore arm or mild fever. More serious side effects are possible, but extremely rare.
Any licensed vaccine is rigorously tested across multiple phases of trials before it is approved for use, and regularly reassessed once it is introduced. Scientists are also constantly monitoring information from several sources for any sign that a vaccine may cause health risks.
Remember, you are far more likely to be seriously injured by a vaccine-preventable disease than by a vaccine. For example, tetanus can cause extreme pain, muscle spasms (lockjaw) and blood clots, measles can cause encephalitis (an infection of the brain) and blindness. Many vaccine-preventable diseases can even result in death. The benefits of vaccination greatly outweigh the risks, and many more illnesses and deaths would occur without vaccines.
https://www.cdc.gov/vaccinesafety/concerns/multiple-vaccines-immunity.html
No, they are not dangerous. An adjuvant is an ingredient used in some vaccines that helps create a stronger immune response in people receiving the vaccine. Aluminium salts, such as aluminium hydroxide, aluminium phosphate, and aluminium potassium sulphate have been used safely in vaccines for more than 70 years. Preservative is used in vaccine to prevent contamination.
Yes, vaccine is a type of medicine that trains the body’s immune system to fight a disease it has not come in contact with before. Vaccines are designed to prevent disease but there are some vaccines that are used to treat cancer.
