14 March 2019 Author : Ana Castro Vaccination is crucial! Vaccines have been given in Portugal since the early 19th century, but it was only in 1965, when the National Vaccination Programme (PNV) was established that health gains became really significant. Since then, millions of children and adults have been vaccinated under the PNV, which is free for everyone . There can be no doubt that vaccination against the main diseases is crucial to child survival. The overall number of deaths in children under the age of five has been gradually decreasing since the introduction of regular vaccination schemes. This means children get a better start in life, which is crucial in ensuring they grow up healthy and achieve their full potential. What are vaccines? A vaccine is a substance produced from an infectious disease-causing agent or one that is chemically similar to that agent. When a person is vaccinated, their immune system reacts as if it had been infected by the agent and then produces antibodies (defences) to the disease. Some vaccines provide total protection . In this case, a person who has been vaccinated does not catch the disease , even if they come into contact with the infectious agent. Others are unable to prevent a disease but can protect against its most severe forms . However, it should be borne in mind that the risk inherent in taking the vaccine will always be less than the risk of the disease. What kinds of vaccines are there? There are basically three types of vaccine : Inactivated vaccines : where pathogens are killed by chemical agents. Their main advantage is the agent’s total inability to infect (multiply in a person’s system). In other words, these vaccines do not cause a disease, but provide protection against it. Most of the PNV and extra-PNV are of this type; Live or attenuated vaccines : where a pathogen obtained from an infected individual or animal is attenuated to make it less virulent. The pathogen maintains the ability to multiply in the body of the vaccinated individual (not causing disease) and induces an appropriate immune response. A single dose is usually enough to produce immunity for life. Examples of these vaccines are: BCG (tuberculosis vaccine); Rotavirus vaccine; Chickenpox vaccine; The measles, mumps, and rubella (MMR) vaccine. Recombinant vaccines : produced by modern molecular biology and genetic engineering techniques. The antigen is produced by other micro-organisms (e.g. yeasts). Examples of these vaccines include: Hepatitis B vaccine; Human papillomavirus (HPV) vaccine. When should we be vaccinated? Except in very special circumstances, the PNV should be followed to the letter . Most vaccines require more than one dose. There are a number of other vaccines that are not part of this scheme, but are equally important. They are recommended , particularly in children. Parents should therefore seek advice from their paediatrician or family doctor. Most vaccines can be given simultaneously as they do not interfere with each other’s immune response. What are the side effects of vaccines? The most common , least serious adverse reactions occur at the injection site and are: Pain; Oedema; Erythema; Redness. They occur in up to 50% of vaccines administered , depending on the type. They are more common after inactivated vaccines . The most widespread reactions are: Fever; Malaise; Fatigue; Irritability; Sleep disturbances; Muscle pain; Headache; Dizziness; Nausea; Loss of appetite. These symptoms are common and non-specific and are more frequent after attenuated vaccines . There are also potentially more dangerous allergic reactions . Fortunately, such reactions are rare and occur in fewer than one in every half million doses. They may be related to any component of the vaccine and usually appear shortly after administration. Always remember that any vaccine-preventable disease is always more severe than the risk of having an adverse reaction to the vaccination. Are there any contraindications to vaccines? Vaccines available under the PNV or on a medical prescription are generally safe . Therefore, the contraindications are: A severe allergic reaction to a previous dose of the vaccine or any of its ingredients; Severe immunodeficiency, for live vaccines only (BCG, measles, rubella, mumps, chickenpox and rotavirus); Pregnancy, only for live vaccines. In children suffering from a severe acute disease , it is advisable to delay vaccination until there is a clinical improvement . If there was a mild allergic reaction to a vaccine, it may be advisable to administer the next dose in hospital. The following are not contraindications: In a previous vaccination: Fever; Pain or swelling at the injection site; Irritability; Drowsiness; A simple febrile seizure (in children aged from six months to five years); Vomiting; Diarrhoea; Pain in the limbs. Mild acute illness ("cold" or diarrhoea), with or without fever; Medications (unless they are immunosuppressants); A chronic disease (of the skin, heart, lungs, kidneys, liver or non-evolving neurological disease); A family member who has had a severe reaction to the same vaccine. If in doubt, ask your paediatrician or family doctor . Children must be vaccinated under approved schemes in the recommended doses and at the right intervals in each country. Vaccines are our best weapon for fighting infections . At the hospitals and clinics in the Hospital da Luz network, there are paediatric specialists who monitor the health of children and young people. Meet the pediatrics team from Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
