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COVID-19 Vaccines and Primary Immunodeficiency

Can PI patients get the vaccine and will it work for them? A doctor who advises the Immune Deficiency Foundation offers her perspective.


A COVID-19 vaccine that’s safe, effective and available would change the world as we’ve come to know it. But for people who have immunodeficiency diseases, it’s not that simple.

More than 400 different immunodeficiencies, such as Common Variable Immune Deficiency (CVID), have been identified and those patients will need to check with their doctors before getting a COVID-19 vaccine.

Here’s how Dr. Kate Sullivan, medical advisor to the Immune Deficiency Foundation, answered some commonly asked questions about COVID-19 vaccines. Sullivan, who is chief of allergy and immunology at Children’s Hospital of Philadelphia, has addressed patients’ concerns in a series of videos on YouTube since the start of the global pandemic.

Can immune-deficient patients receive a COVID-19 vaccine when one (or more of them) are available?

It will depend. Vaccines use different mechanisms and not all types are suitable for all immune-deficient patients, who are prone to serious infections, Sullivan said. Many patients must avoid live attenuated (weakened) vaccines, like the MMR vaccine for measles, mumps and rubella, she said. A replicating viral vector vaccine, like those given for Ebola and dengue fever, also are not suitable, Sullivan said.

But one of the most-discussed vaccine candidates uses mRNA, which would potentially be suitable for immune-deficient patients, she said. Vaccines that rely on DNA also could be appropriate for PI patients. Both are new vaccine technologies, Sullivan said.

“Immune deficient people can get mRNA and DNA vaccines. (These vaccines) aren’t alive. Even though they contain genes, they are not going to cause disease,” Sullivan said.

Will a COVID-19 vaccine be as effective for an immune-deficient patients as it is for someone with a normally functioning immune system?

For many who have immunodeficiencies, the vaccine likely will be as effective as it is for the general population, Sullivan said. But it’s unclear how a potential vaccine will work for those who have antibody deficiencies, she said.

“People with antibody deficiencies will likely have an incomplete response, which doesn’t mean they shouldn’t get it,” Sullivan said.

How many people need to get the vaccine to achieve “herd immunity?” Herd immunity means so many people are immune to the virus because of immunization that it provides a broader protection, even for those who can’t be vaccinated.

Sullivan says this is a hard number to estimate because it will depend on how effective the vaccine is. An educated guess is two-thirds of the population, she said.