What is a vaccine?
A vaccine is a preparation of antigens (particles foreign to the body) that is administered to an individual, eliciting a specific protective immune response from one or more infectious agents.
Vaccine antigens can be whole, killed or attenuated viruses or bacteria, or fragments of such microorganisms. The antigen chosen for a vaccine must be "immunogenic", i.e. it must trigger an immune reaction and not cause the disease.
Vaccines are considered medicines, but they differ markedly from conventional medicines.
How are vaccines produced?
The production processes of vaccines are diverse:
- weakening of the microorganism through successive cultures (e.g. the vaccine against measles, rubella and mumps)
- extraction of the parts of the micro-organism that trigger the immune response (e.g. the vaccine against meningitis C)
- weakening of the toxin that the microorganism produces (e.g. the vaccine against tetanus)
In some cases, more than one microorganism (combination vaccines) may be included in the same vaccine, as is the case with the vaccine against diphtheria, tetanus and whooping cough.
Are vaccines safe?
All vaccines authorised on the European market have a high degree of safety, efficacy and quality, and batch-by-batch certification is required before distribution, after several years of experience and millions of vaccines administered worldwide.
Therefore, serious adverse reactions proven to be associated with vaccines, as well as conditions that constitute precautions or contraindications to vaccination, are rare or very rare. All children and adults must comply with the recommended vaccination schedules for their age and state of health.
How are vaccines authorised?
For a vaccine to be used, an extensive process is required, with different phases over several years:
- Initial phase: laboratory and animal research
- Human trial phase: these usually last several years and consist of three stages, in which, in accordance with strict ethical principles, safety and efficacy, the candidate vaccines are progressively applied to a greater number of people
- Phase after introduction of the vaccine into the community: close surveillance of long-term efficacy and possible adverse reactions
Why should I get vaccinated?
Vaccines save lives. Prior to the introduction of routine vaccination of children, infectious diseases were the leading cause of death in childhood, also causing a great deal of suffering and permanent disability.
Vaccination should be understood as a right and a duty of citizens, actively participating in the decision to get vaccinated, with the awareness that they are defending their health, public health and practicing an act of citizenship.
What if I refuse to be vaccinated?
People who refuse vaccination, with all or some vaccines included in the National Vaccination Program, should express it clearly, preferably in writing, and the information will be registered and filed at the Health Unit.
Am I eligible for vaccination?
yes. Vaccination is a basic right of all citizens. With the creation of the National Vaccination Program, it was possible to reach a high percentage of citizens vaccinated against the diseases targeted by the program, achieving a control of vaccine-preventable diseases, with a huge decrease in the number of deaths and disabilities.
Do vaccines work?
Yes. The vaccine is the most effective way to prevent disease at all stages of life. They defend the body from viruses and bacteria that cause disease, or can even lead to death. Currently, due to the success of vaccination programs, most people are unaware of the seriousness of vaccine-preventable diseases, not realizing the importance and gains conferred by vaccines.
When the person is vaccinated, the body detects the substance and produces a defense, that is, a response is triggered with the formation of antibodies. It is these antibodies that remain in the body and prevent the disease from occurring in the future or, if it does, reduce its intensity. In other words, vaccination causes the immune system to respond quickly and effectively to subsequent contact with the disease.
In addition, vaccination is cost-effective, i.e. its cost largely outweighs the costs associated with treating diseases and their complications (including death).
The professional who vaccinates has the obligation to clarify in advance, in a clear way, about the vaccines that will be administered, explaining the benefits of vaccination and potential adverse reactions, as well as the risk of non-vaccination, when applicable.
What should I do if I have an apparently adverse reaction?
Adverse reactions possibly related to vaccination should be reported to the National Pharmacovigilance System:
- online at RAM Portal – Notification of Adverse Drug Reactions
or - by filling out and sending to INFARMED, I.P. or to a Regional Pharmacovigilance Unit, a specific form "Notification form for health professionals".
In case of difficulties in submitting a notification through the RAM Portal, you can contact INFARMED, through the email address: cimi@infarmed.pt, or by telephone: (+351) 21 798 73 73
.The adverse reaction should also be reported to the treating physician and the person responsible for vaccination.
Do everyone have the right to vaccination?
yes. Everyone has access to free and safe vaccination: the National Vaccination Programme allows all people to receive vaccines according to their age and in competent health services.
What about vaccines that are not included in the National Vaccination Program?
Regarding vaccines that are not included in the National Vaccination Program, ask your GP and family nurse for advice.
What should I do if I have an overdue vaccine?
If for any reason there is a delay in a vaccine, go to your health centre to check if you should have the missed vaccine, even if the recommended ages or dates have already passed.
You should always carry the Individual Health Bulletin (vaccination bulletin) with you, in order to record the vaccine administered.
Is it possible to anticipate or shorten vaccination intervals?
yes. For epidemiological or clinical reasons or not to miss vaccination opportunities, it may be necessary to anticipate the recommended age for the first dose and/or shorten the intervals between doses of the recommended vaccination schedule.
Exceptionally, for some vaccines and in high-risk situations, such as travel or outbreaks, the recommended schedules may be changed using "accelerated schedules" that may not meet the minimum age for the first dose and/or the minimum intervals between doses.
These changes require a medical prescription, including due justification.
Should all children be vaccinated?
yes. To be able to control a disease, it is necessary that a large proportion of people are vaccinated. Eliminating measles, for example, requires at least 95% of people to be vaccinated. Every unvaccinated person is at risk of getting sick and increases the risk of transmitting the disease in the community.
Do vaccines cause pain to my child when they are given?
The discomfort caused by the injection is usually a momentary discomfort, which can be alleviated by distracting the child and avoiding the demonstration of anxiety during vaccination. If the discomfort persists, you can give yourself a light local massage or apply a little ice, without applying pressure.
And in adulthood, what vaccines should be taken?
In adulthood, vaccines against tetanus and diphtheria are recommended, depending on the number of previous doses and age.
In addition to these vaccines, it is recommended that if they were not vaccinated in childhood or if there are increased risk factors, vaccines against measles, rubella and polio.
Why are people more afraid of vaccines than of the diseases they prevent?
People may be more afraid of vaccines than of diseases because they have never seen the effects and their consequences and have not lived through situations a few decades ago, where thousands of children and adults died or were disabled by diseases such as smallpox (now eradicated by vaccination), diphtheria, whooping cough, poliomyelitis and the measles.
What interval needs to be respected between the administration of different vaccines?
The intervals between vaccine doses recommended in the National Vaccination Program allow protection against as many diseases as early as possible.
After all, how long after taking a vaccine are you protected?
The time it takes to achieve protection against the disease depends on the vaccine. Even in vaccines that require several doses, after each administration there may already be some (incomplete) protection, which usually appears 2 weeks or more after each dose.
What is the hepatitis B vaccine used for?
The HBV vaccine protects against infections caused by the hepatitis B, which is transmitted by:
- Sexual intercourse (contact with semen)
- contact with the infected person's blood or fluids (sharing unsterile needles or contact with infected blood)
- from mother to child during childbirth or in the perinatal period (vertical transmission)
What is the risk of not getting the hepatitis B vaccine?
In most children, and in about half of adults, the initial infection has no symptoms (asymptomatic). When infected, children and young people are more likely to become chronic carriers of the virus and develop severe liver disease, including liver cancer.
What is the Haemophilus influenzae b infection vaccine used for?
The Hib vaccine protects against infections caused by the bacterium Haemophilus influenzae serotype b, which is commonly found in the human nasopharynx. It is transmitted from person to person through droplets of saliva, which spread into the air when the patient sneezes or coughs.
What is the risk of not getting vaccinated against Haemophilus influenzae b infections?
The bacterium can cause serious illnesses, such as:
- pneumonia
- bacteraemia
- skin or bone infections
- meningitis
- Epiglottitis
Meningitis has a high mortality rate and often causes mental retardation, blindness or deafness. It mainly affects children under 5 years of age, who can be carriers of the bacteria without showing signs or symptoms of the disease. Infection is rare after the age of 5, so the vaccine is only given until this age.
Is a child who has had Haemophilus influenzae b infections protected or does he need to be vaccinated?
A child who had the disease at less than 24 months of age and who has recovered should be vaccinated as soon as possible. It is not necessary to vaccinate children who have had this disease over 2 years of age, but there is no problem if the child is vaccinated.
What infections does the DTaP vaccine protect me from?
The DTaP vaccine protects against infections caused by the bacteria, or toxins produced by them, from the tetanus (Clostridium tetani), diphtheria (Corynebacterium diphteriae) and whooping cough (Bordetella pertussis).
What vaccines are available against Streptococcus pneumoniae in Portugal?
Two types of vaccines against Streptococcus pneumoniae are available in Portugal:
- 13-serotype Streptococcus pneumoniae (Pn13) infection conjugate vaccine – Prevenar 13®
- 23 serotype (Pn23) polysaccharide vaccine against Streptococcus pneumoniae infections – Pneumovax 23®
Who is vaccination against Streptococcus pneumoniae recommended for?
According to standard of the Directorate-General for Health, the vaccine against Streptococcus pneumoniae infections is recommended for:
- adults over 18 years of age belonging to risk groups – free of charge
- all adults aged 65 years or older (Pneumovax 23® vaccine – Pn23 of 23 serotypes) – special regime with 69% reimbursement
Which risk groups are free of charge for the vaccine?
The Pn23 vaccine is now free for people over 18 years of age belonging to the following risk groups:
- Immunocompetent:
- chronic respiratory insufficiency
- chronic respiratory failure in an LTOT (Long-Term Oxygen Therapy) program
- severe chronic respiratory failure (Pa O2 <70mmHg) and FEV1 <50%
- chronic respiratory insufficiency
- immunocompromised (or at increased risk of bacterial meningitis):
- CSF fistulas
- Cochlear implants (candidates and carriers)
- Asplenia and complement deficit
- anatomical or functional asplenia
- Hyposplenism
- sickle cell disease
- Other hemoglobinopathies with splenic dysfunction
- congenital complement deficiency
- Complement inhibitor therapy
- primary immunodeficiencies
- <a href="https://www.sns24.gov.pt/tema/doencas-infecciosas/vih/" target="_blank" rel="noopener">HIV infection, with CD4+ T lymphocytes<500 cells/mm3)
- transplant candidates (on the active waiting list) and transplant recipients
- medullary or peripheral stem cells
- Solid organs
- active neoplastic disease
- Leukemias
- Lymphomas
- Multiple myeloma
- other malignant tumors
- nephrotic syndrome
Source: Directorate-General for Health (DGS)