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The Good News of COVID-19 Vaccine for 5–11-year-olds

Column Editor: Angela Myers, MD, MPH | Director, Division of Infectious Diseases | Professor of Pediatrics, UMKC School of Medicine | Medical Editor, The Link Newsletter

Let’s first review the data that was presented at the Advisory Committee on Immunization Practices (ACIP) meeting on November 2.¹ The initial phase 2/3 study had 2,268 participants stratified 2:1 vaccine vs. placebo. The median follow-up time for these participants was 2.3 months (up to 3.3 months). The groups were equally balanced between girls and boys, 79% white, 6% Black, 7% multi-racial, 6% Asian, and 21% Latinx. Twelve percent of enrolled children were obese (a known risk factor for more severe disease), and 20% had an identified co-morbidity. Local reactions (redness, swelling, pain at the injection site) were mostly mild or moderate, short-lived, and similar to those of 16–25-year-olds. Similarly, systemic symptoms were mostly mild to moderate, and fatigue, headache, and muscle aches were most common at 39.4%, 28%, and 9.8%, respectively. Chills were seen in 9.8% and fever was uncommon at 6.5%. Data was also presented that showed no differences in local or systemic reactions based on COVID-19 seropositivity status at baseline. None of the serious adverse events (SAEs) reported after vaccination were deemed to be related to vaccine (e.g., septic arthritis, epiphyseal fracture, foreign body ingestion). There were no cases of anaphylaxis, myocarditis or pericarditis, Bell’s palsy, or appendicitis.

Now for the good part. How effective was the vaccine in the trial? The seroresponse criteria was met with a ≥4 fold increase in titer from baseline (pre-vaccine) as well as the immunobridging criteria.¹ The immunobridging criteria was defined as ≥0.8 geometric mean response (GMR) of the geometric mean titer (GMT) in 5–11-year-olds over the GMT in 16–25-year-olds with a lower bound to the confidence interval of >0.67.¹ There was essentially zero difference between the two age groups and a GMR of 10.4 (95% CI 0.93, 1.18).¹ Although the data are limited, they show that, consistent with the adult data, children who had previous infection developed higher antibody titers than those who did not have previous infection. Neutralization titers were conducted on a random subset of children with findings that the neutralization titers were comparable between the reference strain the trial used from Seattle, Washington (original Wuhan strain), and the new Delta variant strain. Vaccine efficacy was reported as 90.7% (95% CI 67.7, 98.3) for COVID-19 infection seven or more days after dose 2 with only three cases in vaccinated participants compared to 16 in unvaccinated.¹ I expect an even more pronounced difference over time, as the follow-up period is two months currently.   

A few final thoughts based on questions you might receive from patient families, and you may be wondering yourself.

1. Should my child get vaccinated if they’ve already had infection?

Vaccination is important regardless of previous infection because the data have shown that antibody response due to infection is lower, less consistent, and less cross-neutralizing for evolving variants than response to vaccine. Antibody responses are also lower in those with mild or asymptomatic infection, which is more common in children. Vaccination after infection enhances protection, provides broader cross-protection and decreases risk of subsequent infection. Finally, more than 7 million teenagers (12-15 years) have received Pfizer’s vaccine at this point, and no safety concerns have been raised about vaccination after infection.

2. I have heard that children do not get as sick with COVID-19 as adults do. Is this true? 

Yes, a lower percentage of children develop severe disease compared to adults. However, nearly 2 million children in the 5–11-year age group have been COVID-19 infected, with 8,300 hospitalizations and 94 deaths, representing 1.7% of deaths from any cause in this age range. Children in this age group also make up the largest proportion of multisystem inflammatory syndrome in children (MIS-C) cases (44%), with nine deaths (20% of MIS-C deaths overall). Additionally, 70% of hospitalized children had an underlying condition (obesity was most common), and severe cases were seen more frequently in children of color.²

3. I am worried about my child developing myocarditis from the vaccine. What is the risk of that?

Myocarditis following COVID-19 vaccine is rare and is associated with less severe laboratory abnormalities (e.g., lesser changes in troponin, white blood cells, C-reactive protein, and brain natriuretic peptide) and shorter time to return of normal heart function compared to children with MIS-C or viral associated myocarditis (<5 days for vaccine vs. 3+ weeks for infection). Additionally, health care providers' reports show that 91% of their patients had completely recovered within three months.³ The risk of myocarditis is highest in boys ages 12-29 (occurring in 40-50/million second doses)⁴ and is lower than the risk of myocarditis from COVID-19 infection (120,000/million infections) or MIS-C (670,000/million cases).

4. Should my child get vaccinated after having MIS-C? 

The benefit of vaccination outweighs the risk in children with a history of MIS-C provided it has been at least 90 days since their MIS-C diagnosis, they have fully recovered and have normal cardiac function, live in a high transmission area or have a high exposure risk, and their MIS-C occurred before any COVID-19 vaccination.³ Additional factors to be considered are the patient’s risk of severe disease (e.g., chronic conditions) and the timing of any immunomodulatory treatments for either COVID-19 or MIS-C.

5. What dose of vaccine should my child get? They are almost 12 or may turn 12 in between doses.

Vaccine doses are traditionally based on age instead of weight, which is different from many children’s medications, including common OTC medications such as acetaminophen and, of course, antibiotics. Let’s consider three scenarios:

a. 5-11 years at time of both doses. Both doses should be 10 µg (orange top vial).

b. 11 years at first dose but will be 12 on or before second dose. Preferred is 30 µg dose. BUT - per the FDA EUA Fact Sheet,⁵ for patients in this category, a second 10 µg dose is still considered valid (exact wording in box below). Per the CDC ACIP presentation, either dosage is considered adequate and not an EUA error.⁶

c. 12 years for both doses. Both doses should be 30 µg (either purple or gray top vial).  

Language from the FDA EUA Fact Sheet⁵

This last question has been the most frequent question we have received from patients, families and community providers. It is a great question. Based on the information above, it seems that physicians have the latitude to use what they have available. If new information or recommendations are published regarding this allowance, we will send out an update.

Finally, a great resource from the North American Society for Pediatric and Adolescent Gynecology was sent to me by our Chief of Gynecological Surgery. This talking-points document discusses the COVID-19 vaccine and fertility, pregnancy, and menstrual cycles, along with some resources and links. It can be accessed here: NASPAG Talking Points - COVID-19 Vaccine and Reproductive Health.

References:

1. Accessed November 3, 2021. https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2021-11-2-3/02-COVID-Gurtman-508.pdf
2. Accessed November 3, 2021. https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2021-11-2-3/03-COVID-Jefferson-508.pdf
3. Accessed November 3, 2021. https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2021-11-2-3/04-COVID-Oster-508.pdf
4. Gargano JW, Wallace M, Hadler SC, et al. Use of mRNA COVID-19 vaccine after reports of myocarditis among vaccine recipients: update from the Advisory Committee on Immunization Practices — United States, June 2021. MMWR Morb Mortal Wkly Rep. 2021;70:977-982. doi:http://dx.doi.org/10.15585/mmwr.mm7027e2
5. Accessed November 3, 2021. https://www.fda.gov/media/153717/download
6. Accessed November 3, 2021. https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2021-11-2-3/07-COVID-Woodworth-508.pdf