close   X

11/10/21blog post

Q&A: The COVID-19 vaccine, kids and weight

With approval from the Food and Drug Administration and the Centers for Disease Control, kids ages 5 to 11 are now eligible to receive the COVID-19 vaccine. Through vaccination, this age group can help protect themselves, their families and the community from the COVID-19 virus.

Understandably, many parents still have questions about the vaccine and whether it’s safe to give to their child. One of the most common questions being asked is about the vaccine dosage and their child’s weight. We sat down with Sherman Alter, MD, infectious disease provider to discuss this topic and how the Pfizer vaccine compares to typical childhood vaccinations.

Why is eligibility for the Pfizer COVID-19 vaccine based on age and not weight?
For many years, we have administered the same vaccine dose for persons of differing sizes. All of the routine childhood vaccines have historically been administered to children of various sizes while using the same dose of the vaccine. It is the same for adults (ex., we give the same vaccine to a 280-pound football player as we would to a 90-pound ballerina). Both individuals handle the vaccine dose the same way and both develop an excellent immune response without any differences in the rates of adverse reactions.

What other vaccinations are based on age and not weight?
There are some vaccines that are administered differently based on age. We give a Diphtheria-tetanus-pertussis (whooping cough) vaccine (DTap) to children that is a little different than the Tetanus-diphtheria-pertussis vaccine (TdaP) that teenagers and adults receive. The only difference between the two is really the amount of diphtheria (toxoid) in the two shots. The younger age dose has a little bit more of the diphtheria toxoid (to which one makes antibodies) which at times can cause more side effects (mostly mild) when given to older individuals.

We at times can give an influenza vaccine to older persons that has a little bit more of the inactivated flu virus – the immune response in some older persons is not as “strong” as in younger people and they need just a bit more of the vaccine constituents to develop a very good immune response.

The only weight-based change for a vaccine dose is for hepatitis B vaccine. We do not administer the vaccine to an infant unless he/she weighs more than 2 kg. (4.4 pounds).

All other vaccines are administered in the same dosages regardless of weight.

What if my son is four-years-old, but the size of an older child. Can he get vaccinated?
No – the vaccine is only authorized for children 5 years and older.

If my daughter is 11-years-old, should I wait to give her the vaccine for 12+? Will the “child-sized” vaccine be effective for an older, bigger child at the top of the age range?
I would administer the vaccine when she is 11-years-old.  This would protect her right now. There does not seem to be a major difference in development of antibodies against the virus between the two age groups.

The key is to protect your child now and make sure that he/she is keeping up with other recommended childhood vaccines, as well.

You can make an appointment for your child, 5-11 years old, to receive their COVID-19 vaccine at one of our Dayton Children's locations. Visit today to view the locations and many times available for your family!

Alter Sherman

Sherman Alter, MD

infectious disease
view full bio