Pfizer COVID-19 Vaccine For Kids : What You Need To Know!

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Here is what you need to know about the Pfizer COVID-19 vaccine for 5-11 year old kids!


Pfizer Vaccine For 5-11 Yo Kids : What You Need To Know!

On 22 October 2021, the US FDA publicly released the Pfizer-BioNTech briefing document on their clinical trial of the COMIRNATY vaccine in 5-11 year-old children.

On 29 October 2021, the US FDA officially approved the emergency use of the Pfizer-BioNTech COVID-19 vaccine in 5-11 year-old children.

This Pfizer COVID-19 vaccine for kids is different from the COVID-19 vaccine for older children and adults in many ways, so let me summarise the key differences…

Pfizer COVID-19 Vaccine For Kids : What You Need To Know!

Lower Paediatric Dose

The paediatric dose of the Pfizer vaccine is only 10 micrograms (mcg). This is only 1/3 of the dose used for adults and adolescents.

Two Doses For Most Children

The Pfizer paediatric COVID-19 vaccine will still be administered as a two-dose primary series for most children 5 through 11 years of age.

However, a three-dose primary series may be given to certain children 5 through 11 years of age:

  • who have undergone solid organ transplantation, or
  • who have been diagnosed with conditions that have an equivalent level of immunocompromise.

New 10-Dose Vial

The new Pfizer COVID-19 vaccine for kids 5-11 years old in age, is supplied in a new 10-dose vial, with an orange cap and a label with an orange border.

Pfizer-BioNTech paediatric COVID-19 vaccine design for children

Must Be Diluted Before Use

The content of the vial must be diluted with 1.3 ml of sterile 0.9% sodium chloride, to derive 10 doses of 0.2 ml in volume.

Healthcare workers must be aware of this dilution requirement, as the newer Pfizer vaccine with a gray cap (for individuals 12 years and older) no longer requires dilution.

Smaller Intramuscular Injection

The Pfizer paediatric COVID-19 vaccine is given as a 0.2 ml intramuscular injection. This is a smaller volume than the adult dose – 0.3 ml.

So parents should be aware that the paediatric dose has a lower volume, when observing their children’s vaccinations.

More Stable Formulation

In addition to the lower dose, Pfizer’s paediatric vaccine has an improved formulation that is more stable. For those who want to know what changed, Pfizer :

  • replaced the phosphate-buffered saline (PBS) with a Tris buffer
  • removed sodium chloride and potassium chloride from the buffer formulation

This new formulation will allow the vaccine to be kept in a normal refrigerator at 2°C to 8°C (35°F to 46°F) for up to 10 weeks, instead of just 4 weeks.

In addition, it will last longer – 12 hours, instead of just 2 hours – at room temperature (up to 25°C / 77°F), after being thawed.

Read more : Did Pfizer add heart attack drug to COVID-19 vaccine for kids?

Did Pfizer Add Heart Attack Drug To COVID Vaccine For Kids?

9 Month Expiry Date

The Pfizer paediatric COVID-19 vaccine has a 9-month expiry date, from the printed manufacturing date.

Expiry Date
06/2021 28 February 2022
07/2021 31 March 2022
08/2021 30 April 2022
09/2021 31 May 2022
10/2021 30 June 2022
11/2021 31 July 2022
12/2021 31 August 2022
01/2022 30 September 2022
02/2022 31 October 2022

90% Efficacious

The study showed that the lower paediatric dose of the Pfizer-BioNTech vaccine was 90.7% efficacious in preventing symptomatic COVID-19 infection.

Efficacious Against Delta Variant

The study also showed that the Pfizer paediatric vaccine produced high neutralising antibody titres against the Delta (B.1.617.2) variant at 1 month after Dose 2.

One Month
After Dose 2
Geometric Mean Titres
USA-WA1/2020 (Reference) 365.3 +36.5X
B.1.617.2 (Delta) 294.9 +29.5X
Unvaccinated 10 Baseline

Same Dose Interval

Pfizer, however, maintained the same 21-day dose interval. This may mean that the high antibody levels the new paediatric vaccine produces will similarly wane over time, perhaps requiring a booster dose after six months.

As the UK has shown with their AstraZeneca vaccine, increasing the dose interval results in longer-lasting protection.

That said, antibody levels are not an accurate assessment of an individual’s immunity against COVID-19.

Read more : Why delaying AstraZeneca Dose 2 INCREASES efficacy?

Did WHO Say Children Should NOT Get COVID-19 Vaccine?

Fewer Side Effects

The lower paediatric dose of the Pfizer-BioNTech vaccine naturally produced fewer side effects, with no severe side effects noted. They were mostly :

  • pain at injection site : 71-74%
  • headache : 54-61%
  • fatigue : 60-66%
  • muscle pain : 27-41%
  • chills : 25-40%
  • joint pain : 13-22%
  • fever : 7-17%

Side note : It is interesting to note that even the placebo causes common symptoms like fatigue, headache and muscle pain. This shows just how important it is to conduct a randomised controlled trial.

Pfizer COVID-19 Vaccine For Kids : What You Need To Know!

Likely Safer

The much lower dose should ameliorate, if not eliminate, the risk of myocarditis / pericarditis that was highest in adolescents and young adults.

There were no cases of pericarditis or myocarditis in the Pfizer study that involved over 2,260 children, through approximately 3 months of follow-up after Dose 2.

However, the risk of myocarditis in adolescents is only about 1 in 50,000, so we will only know for sure once mass vaccinations have begun.

For a better perspective of the risk of developing myocarditis, I created this comparison table for you :

Myocarditis Risk Per Million People Difference
COVID-19 Patient 450 +2208%
Pfizer Vaccine
(Adult Dose)
20 +2.6%
Normal Population 19.5 Baseline

As you can see, the risk of developing myocarditis is MUCH higher if your child gets infected with COVID-19, compared with getting a full dose of the Pfizer vaccine.

I have no idea if the myocarditis risk is truly lower with the paediatric dose, but it surely cannot be more than the full dose that is currently being administered to adolescents.


FDA Panel Recommends Pfizer Vaccine For 5-11 Yo Kids!

On 26 October 2021, the FDA advisory panel met to discuss the data, and voted 17 in favour (with one abstention) of recommending an emergency use authorisation for the new Pfizer paediatric vaccine.

Children in this age group currently accounts for 9% of reported COVID-19 cases in the US, and approximately 40% of all paediatric COVID-19 cases, with 1/3 of hospitalised children requiring ICU care.

While the risk of hospitalisation and death is relatively low for children, they still suffer from serious complications like :

  • myocarditis
  • multisystem inflammatory syndrome (MIS-C)
  • long COVID

One UK study, for example, found that 7% to 8% of children continue to have symptoms more than 12 weeks after they were diagnosed with COVID-19.

Read more : What’s The Difference Between Full FDA Approval vs EUA for Vaccines?


FDA Panel Approves Pfizer Vaccine For 5-11 Yo Kids!

On 29 October 2021, the US FDA officially approved the emergency use of the Pfizer-BioNTech COVID-19 vaccine in 5-11 year-old children.

This was based on their expert panel’s earlier approval, and their own evaluation of the data from Pfizer’s paediatric clinical trial.

Here is a short summary of the US FDA’s findings on the Pfizer-BioNTech vaccine for 5-11 year-old children :

Effectiveness : Immune responses of children 5 through 11 years of age were comparable to those of individuals 16 through 25 years of age. In addition, the vaccine was found to be 90.7% effective in preventing COVID-19 in children 5 through 11.

Safety : The vaccine’s safety was studied in approximately 3,100 children age 5 through 11 who received the vaccine and no serious side effects have been detected in the ongoing study.

Read more : FDA Authorises Pfizer-BioNTech Vaccine For 5-11 Yo Children!

Updated @ 2022-01-08 : Added new details of the Pfizer COVID-19 vaccine for kids.

Updated @ 2021-11-02 : Added details of the US FDA emergency use authorisation.
Originally posted @ 2021-10-29


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Dr. Adrian Wong has been writing about tech and science since 1997, even publishing a book with Prentice Hall called Breaking Through The BIOS Barrier (ISBN 978-0131455368) while in medical school.

He continues to devote countless hours every day writing about tech, medicine and science, in his pursuit of facts in a post-truth world.


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