January 22, 2025
Healio reports on a recently published 10-year study into childhood vaccine guideline adherence. It found nearly 1 in 6 children in the United States received at least one vaccine outside the guidelines set forth by the CDC’s Advisory Committee on Immunization Practices. The most common vaccine that experienced invalid doses was the three-dose rotavirus vaccine. Study authors noted vaccinating outside of the guidelines raises concerns about inadequate protection and safety.
Of the 161,187 children included in the study, 15.4% had at least one invalid vaccine dose over the study period. The most common invalid doses were seen with rotavirus, Haemophilus influenzae type b, hepatitis A, and hepatitis B. The authors note these were either given at too young of age, too soon relative to previous dose, or given at too old of age in the case of rotavirus.
ACIP recommends a repeated dose of any vaccine administered too early to complete the series. The portion of children completing their series increased from 29.5% in 2011 to 52.9% in 2020. Authors note this as an unexpected and positive finding.
The factors for invalid dosage are cited as having seen three or more providers, children moving between states, and receiving doses from a hospital-owned clinic compared to private clinics. An accompanying editorial noted possible next steps to reduce vaccine administration errors and educating providers about resources available to assist and guide them to prevent errors such as those stemming from different products targeting the same disease having different schedules.
The study included children aged 19 to 35 months and the recommended vaccines for this group. The vaccines included four doses of DTaP and pneumococcal conjugate, three or four doses (depending on type) for Haemophilus influenzae type b, three doses for hepatitis B and polio, two or three doses (depending on type) of rotavirus, two shots for hepatitis A and seasonal influenza, and the first dose of MMR and varicella.
Data came from the National Immunization Survey-Child survey of vaccine history between 2011 and 2020. Parents were asked about their children’s vaccine timing. Percentages were weighted due to decreased response rate between 2018 and 2020 compared to 2011 and 2017. This was attributed to switching to cell phones only from landlines and cell phones, in the respective time frames.
PIDS member and ACIP liaison, Alexandra Yonts, commented on the article. “Of the children who received vaccine doses earlier than recommended per the ACIP schedule, less than half received an additional valid dose after the minimum interval/age to complete the series. Of highest concern, only 13.6% of children who received their third HepB dose too early appropriately completed the series with an additional dose after age 164 days. The implications of this are unknown and potentially leave these children at increased risk for Hepatitis B infection and sequelae, as immunogenicity studies have demonstrated a need for a dose after six months of life for durable antibody production. The authors also highlight that of the small percentage (0.1%) of children given an MMR vaccine before 12 months of age, only 39.7% received a valid dose after 12 months of age, placing these young children at increased risk in light of increasing measles outbreaks in the community.
“Based on the results of this study, it is my opinion that simplification or harmonization of combination vaccine dosing across products and an automated, universal vaccine record are needed to decrease the number of invalid vaccine doses given in the future and achieve optimal protection for our youngest patients from vaccine preventable diseases.”