Adverse Reactions Following Vaccination in Children

Local Reactions

• Injection site reactions are the most frequently reported adverse events, occurring in 10-64% of vaccinated children, according to the Centers for Disease Control and Prevention 1
• Pain, tenderness, erythema, and induration/swelling at the injection site typically resolve within 2 days, as recommended by the Centers for Disease Control and Prevention 2, 1

Systemic Reactions

• Fever is the most common systemic reaction, beginning 6-12 hours post-vaccination and persisting 1-2 days, as reported by the Centers for Disease Control and Prevention 3, 4, 5
• Age-specific fever rates after influenza vaccination are 11.5% in children aged 1-5 years, 4.6% in children aged 6-10 years, and 5.1% in children aged 11-15 years, according to the Centers for Disease Control and Prevention 3, 4, 5
• Among high-risk children aged 6 months-4 years, fever rates can reach up to 27%, as reported by the Centers for Disease Control and Prevention 3, 5
• Irritability, decreased appetite, and altered sleep patterns are common, particularly after pneumococcal conjugate vaccine, as noted by the Centers for Disease Control and Prevention 2
• Malaise and myalgia typically resolve within 1-2 days, according to the American Academy of Pediatrics 1
• Gastrointestinal symptoms including diarrhea, vomiting, and nausea occur in >1% of vaccinated children, as reported by the Centers for Disease Control and Prevention 2

Serious Adverse Events

• Immediate hypersensitivity reactions include hives, angioedema, allergic asthma, and systemic anaphylaxis, as reported by the Centers for Disease Control and Prevention 3, 1
• Febrile seizures have been reported but are uncommon, according to the American Academy of Pediatrics 6, 4
• Guillain-Barré Syndrome was associated with the 1976 swine influenza vaccine at a rate of <10 cases per 1 million vaccinated, though this association has not been consistently demonstrated with modern vaccines, as noted by the Centers for Disease Control and Prevention 3, 1
• Bronchiolitis, gastroenteritis, and pneumonia were the most commonly reported serious adverse events after PCV13, though causality was not established, as reported by the Centers for Disease Control and Prevention 2
• Lymphadenopathy localized to the injection site region has been documented, according to the Centers for Disease Control and Prevention 2

Important Clinical Considerations

• Most respiratory or gastrointestinal symptoms occurring after vaccination represent coincidental illnesses unrelated to the vaccine, as noted by the American Academy of Pediatrics 7
• Inactivated vaccines contain no live virus and cannot cause the disease they prevent, according to the Centers for Disease Control and Prevention 7
• Healthcare professionals must report ALL clinically significant adverse events to VAERS, even without certainty of causation, as recommended by the Centers for Disease Control and Prevention 3, 5, 1
• Any adverse event resulting in hospitalization, disability, or death requires VAERS reporting, according to the American Academy of Pediatrics 5, 1
• The Institute of Medicine specifically recommends reporting potential neurologic complications including demyelinating disorders, as noted by the Centers for Disease Control and Prevention 3
• Large-scale VSD studies of 251,600 children showed no increase in clinically important medically attended events during the 2 weeks after TIV vaccination compared with control periods, as reported by the Centers for Disease Control and Prevention 6, 4
• PCV13 and PCV7 have comparable safety profiles with no statistically significant differences in serious adverse events, according to the Centers for Disease Control and Prevention 2
• Acetaminophen 10-15 mg/kg every 4-6 hours can be administered for fever or discomfort, as recommended by the American Academy of Pediatrics 5
• Prophylactic acetaminophen is NOT recommended routinely but may be considered for children with a history of seizures or family history of convulsions, according to the American Academy of Pediatrics 5

Post-Vaccination Observation Period for Pediatric Patients

Recommended Observation Period

• The American College of Pediatricians and the Advisory Committee on Immunization Practices (ACIP) recommend a 15-20 minute observation period following vaccination to monitor for syncope and immediate allergic reactions, particularly in adolescents and young adults who are at higher risk for fainting 8
• The observation period is crucial for patients who experience syncope, as they should be observed until symptoms completely resolve 8
• The Centers for Disease Control and Prevention (CDC) and ACIP emphasize that this waiting period is especially important for adolescents and young adults, who experience syncope more commonly than other age groups 8

Rationale for the Waiting Period

• The observation period serves to prevent and manage syncope, which can rarely result in serious injury from falls, and the risk is highest in the immediate post-vaccination period 8
• Keeping patients seated or lying down during observation prevents fall-related injuries 8
• Immediate anaphylactic reactions, though rare, can occur and require prompt recognition and treatment, and anaphylaxis typically develops within minutes of vaccine administration 9, 10, 11
• The observation period allows for immediate medical intervention if needed, and healthcare providers should watch for signs of syncope and immediate hypersensitivity reactions 8, 9

Special Considerations

• For multiple simultaneous vaccinations, the same 15-20 minute observation period applies regardless of the number of vaccines administered 8