Are vaccines safe? Yes, vaccines are safe, they have a high degree of safety, efficacy and quality, with years of experience and millions of vaccines administered worldwide. Therefore, all children and adults must comply with the vaccination schedules recommended for their age and health status. No vaccine is completely free from causing adverse events. However, the risks of serious complications from vaccines are much lower than those of the diseases they protect against. What are the most common adverse reactions to vaccines? Generally, vaccine reactions or side effects are mild and self-limiting, which means that they disappear without treatment. Some of these side effects are: Pain, edema (swelling) and / or redness (redness) at the injection site; Slight increase in temperature / mild-moderate fever, which usually resolves in 24-48 hours; Headache and / or muscle. For these adverse reactions: If your child has a fever , give them an antipyretic at an appropriate dosage for their age and weight. If they have pain, redness, swelling, and heat at the injection site, apply ice several times a day (for short periods and never in direct contact with the skin). In very rare cases, more serious side reactions may occur, such as anaphylaxis. However, vaccination services are trained to control these reactions. As a preventive measure, it is advisable to remain in the service where the vaccination is carried out within 30 minutes after the administration of any vaccine. Specific reactions to some vaccines Hepatitis B vaccine Frequent reactions (1 in 10 vaccinated): fever and local reactions (pain, redness and slight swelling at the injection site); Rare reactions: fatigue / prostration, joint and / or muscle pain, headache, nausea, dizziness. DTPa / Hib / VIP (Penta) and DTPa / VIP (Tetra) - Vaccine against diphtheria, tetanus, whooping cough, invasive disease by Haemophilus influenzae b and polio Frequent reactions: fever, irritability, drowsiness, local reactions (more frequent in the 4 th and 5 th doses); Rare reactions: high fever (1 in 16,000 vaccinated), seizures (1 in 14,000 vaccinated), persistent crying for more than 3 hours (1 in 1,000 vaccinated), vomiting; Very rare reactions: severe allergy (1 in 1,000,000 vaccinated), abnormal movements (hypotonic / hyporeactive episodes). Td - Tetanus and diphtheria vaccine Frequent reactions: mild fever and local reactions (pain, redness and slight swelling at the injection site), hard and painful lump at the injection site, which persists for a few weeks; Rare reactions: headache, muscle and / or joint pain, severe allergy (1 in 1,000,000 vaccinated). MenC - Vaccine against meningitis C Frequent reactions: mild fever and local reactions (pain, redness and slight swelling at the injection site); Rare reactions: Less than 2 years: irritability, unusual / persistent crying and changes in sleep pattern, nausea, vomiting, abdominal pain, diarrhea, loss of appetite; Over 2 years: headache, muscle pain (limbs); Adolescents / adults: muscle and / or joint pain. VASPR - Vaccine against measles, epidemic mumps and rubella Frequent reactions: Less than 2 years: high fever (> 39ºC), rash (small red spots / spots on the skin) between 5 to 12 days after vaccination, local reactions (pain, redness and slight swelling at the injection site); Adolescents / adults: joint pain / arthritis, 1 to 3 weeks after vaccination. Rare reactions: irritability, loss of appetite, unusual / persistent crying, nausea, vomiting, diarrhea, runny nose, altered sleep pattern; Very rare reactions: severe allergy (1 in 1,000,000 vaccinated), transient thrombocytopenia (decreased blood platelets) (1 in 30,000 vaccinated). HPV - Vaccine against human papilloma virus Frequent reactions: local reactions (pain, redness and swelling at the injection site), headache, dizziness; Rare reactions: fever > 38.8ºC, short-term fainting with or without convulsive movements (after the vaccine is administered, especially in adolescents); vigilance is recommended, in a sitting or lying position, for 15 to 30 minutes, to prevent the risk of falling. Vaccine against serogroup B meningococcus Frequent reactions: Less than 10 years old: fever, irritability, unusual crying, eating disorders, drowsiness, headache, diarrhea, vomiting, skin rash (most frequent between 12-23 months of age, being uncommon after booster), joint pain, local reactions (pain, redness of the skin, swelling and induration at the injection site); Over 10 years and adults: headache, nausea, malaise, muscle and / or joint pain and local reactions (pain at the injection site, resulting in the inability to perform day-to-day activities); Rare reactions: high fever (> 40ºC), convulsions (including febrile seizures), dry skin, pallor and / or short-term fainting with or without convulsive movements (after the vaccine is administered, especially in adolescents); vigilance is recommended, in a sitting or lying position, for 15 to 30 minutes, to prevent the risk of falling. Very rare reactions: severe allergy, Kawasaki disease (fever for more than 5 days associated with rash on the trunk and sometimes followed by flaking of the skin on the fingers / toes, swollen lymph nodes in the neck, red eyes, lips, red throat and tongue). ROTA - Vaccine against rotavirus Frequent reactions: fever, diarrhea, vomiting, runny nose; Rare reactions: wheezing, severe allergy and intestinal invagination (intestinal obstruction in which a segment is trapped inside another adjacent segment, whose symptoms may include usually severe abdominal pain, persistent vomiting, blood in the stool and bloating). BCG - Vaccine against tuberculosis (currently this vaccine is made only at risk groups) BCG vaccination: It does not cause fever; A small red nodule appears at the injection site which, after 2 to 4 weeks, becomes a small wound; This wound heals after 2 to 5 months, leaving a superficial scar about 5 mm in diameter; Disinfectants, ointments or dressings should not be applied to the reaction site. Adverse reactions: Frequent reactions: regional lymphadenitis, that is, an increase in the volume of ganglia located close to the administration site; Rare reactions: suppurative lymphadenitis (1 in 2000 vaccinated), that is, an increase in volume and a purulent collection of ganglia located near the site of administration. Do you know what a vaccine is? A vaccine is a preparation of antigens (particles foreign to our organism), which when administered to a person causes a specific protective immune response to one or more infectious agents. Vaccine antigens can be whole, killed or attenuated bacteria or viruses, or fragments of these microorganisms. The antigens chosen for the vaccines are immunogenic, that is, they trigger an immune reaction and do not cause the disease. Remember The vaccines used today are effective and safe, and are subject to a strict quality control; No common adverse reaction is more serious than the vaccine target disease. Author : Marta Cabral Learn more about the National Vaccination Program . Meet the Pediatrics team of 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.
