COVID-19 Vaccine in Young Children (Ages 5-11)

COVID-19 Vaccine in Young Children (Ages 5-11)

Mel Herbert 

• The US FDA has approved the Pfizer-BioNTech (Comirnaty) vaccine for administration to children ages 5-11 years.
  • The approval and CDC recommendation are based on an ongoing study of 4700 children in the US, Finland, Poland, and Spain.
  • The mRNA dose is one-third of the adult dose (ie, 10µg mRNA vs 30µg in those > 12 years old)
  • The regimen consists of 2 vaccine administrations, separated by least 3 weeks (ie, the same as the adult regimen)
  • The vaccine uses a new buffer, the TRIS buffer used in other FDA-approved vaccines. This makes it more stable at higher temperatures.
  • There is no data yet on co-administration with the flu vaccine in children.
    • In adults, this is considered safe and combined formulations are coming.
• Why 10 mcg?
  • A cohort study that looked at 265 children that received the lower dose and compared them to older patients (over age 12) that received the higher dose found a similar immune response.
• An analysis performed 7 days after the second dose found:
  • 3 cases of COVID-19 occurred among 1305 vaccinated children.
  • 16 cases occurred among 663 placebo patients.
  • The reported efficacy was 90.7%.
  • There were no deaths in either group.
  • The data are very similar to those in adults and children > 12 years.
  • Side effects
    • Arm pain (lasting longer, 1-2 days after the second dose).
    • Mild to moderate headache was common.
    • Myocarditis
      • Myocarditis was not reported in the current series.
      • It has been more commonly reported with the Moderna vaccine.
      • FDA modeling shows that the risk of hospitalization with vaccine-related myocarditis is much less than the risk of hospitalization with COVID-19 infection.
• Epidemiology
  • There have been 146 deaths in the US of children ages 5-11 (total population of about 28 million) and 8,300 hospital admissions.
  • As of Oct 10, 2021, there have been 1.9 million cases of COVID-19 in the US confirmed by testing, however, serological data indicate a far greater penetration of the virus, with 38% of children demonstrating SARS-CoV-2 antibodies in September 2021.
  • Unvaccinated children who acquire COVID-19 have a lower antibody response than those that receive the vaccine, but the protection following natural infection appears to hold for at least 6 months.
  • The CDC estimates that one case of MIS-C occurs for every 3,200 pediatric COVID-19 cases.
    • 60-70% require ICU care
    • 1-2% mortality
• Data on the Moderna (mRNA-1273) vaccine for children aged 5-11 years old is pending and expected to be reviewed in January.

References:

FDA Notice: https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/comirnaty-and-pfizer-biontech-covid-19-vaccine

TWIV Updates: https://www.microbe.tv/twiv/twiv-823/

CDC: Mortality and Morbidity data on children 5-11: https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2021-11-2-3/03-COVID-Jefferson-508.pdf

UCDavis Flu vs Covid data in Children: https://health.ucdavis.edu/health-news/newsroom/experts-answer-parents-questions-about-covid-19-vaccine-for-kids-ages-5-11/2021/11