On October 29, 2021, the FDA authorized the use of a 10mcg dose of Pfizer-BioNTech COVID-19 mRNA vaccine in children 5 through 11 years of age. The vaccine was authorized to be administered intramuscularly as a two-dose series, three weeks apart.
The authorization of the vaccine was based on two cohort studies, involving 3,100 children who received the vaccine, and 1,538 children who received a placebo. Only 1,444 vaccine recipients were monitored for safety at least two months after the second vaccine dose.
In the Cohort 1 study (C4591007) 1,518 children between the ages of 5 and 12 years received a vaccine dose, however, only 1,444 (95.1 percent) were followed for safety concerns at least two months after the second vaccine dose. The most frequently reported adverse events among Cohort 1 study participants included injection site pain (71 percent), fatigue (39.4 percent), and headache (28 percent). Most occurred after the second dose, and generally within two days of vaccination. Lymphadenopathy (swelling of the lymph nodes) was the most common unsolicited adverse event among children who received the vaccine (N=13 or 0.9 percent). Fourteen children who received the vaccine experienced a hypersensitivity reaction, compared to four children in the placebo group. These events primarily included dermatitis and rash.
The Cohort 2 study involved 1,591 children who received the vaccine and 778 children who received the placebo. At the time of the data cutoff (Oct. 8, 2021), this population had only been monitored for 2.4 weeks post dose two. According to the FDA, data collection was ongoing. Among the 3,109 vaccine recipients in both Cohort studies, four serious adverse events occurred; however, all were considered by the trial investigators to be unrelated to vaccination. These included an upper limb fracture, an infection of the knee, a foreign body ingestion, and an epiphyseal fracture. One vaccine recipient, a six-year-old female, developed Henoch-Schonlein purpura 21 days post dose one but this adverse event was reported to be non-serious. No deaths occurred among any study participants.
Additional unsolicited adverse events reported among vaccine recipients included swelling under the skin triggered by an allergic response (angioedema), administration site disorders, swelling of the face, skin and subcutaneous tissue disorders, urticaria, arthritis, musculoskeletal and connective tissue disorders, synovitis, eye disorder, conjunctivitis, injection site rash, skin and subcutaneous disorder, dermatitis, rash, and eczema. No cases of myocarditis or pericarditis were reported among study participants; however, there were 12 cases where chest pain was reported. Six cases occurred among those receiving the vaccine, and six among placebo recipients.
There were no participants in Cohort 1 that withdrew from the clinical trial due to an adverse event; however, one participant in the Cohort 2 study withdrew following dose one due to fever and worsening of neutropenia (this individual had a prior diagnosis of benign transient neutropenia).
Vulvar ulcers in adolescent girls between 12-16 years of age were also reported after the second dose of Pfizer-BioNTech COVID-19 vaccine. An April 2022 published case study found an association between the vaccine and genital ulcers, with symptoms presenting within 24 hours of vaccination. Additional reports of genital ulcers following vaccination have been reported in VAERS.
