Question:
My 13-year-old son has Trisomy 21, ASD, growth hormone deficiency, hypothyroidism, and psoriasis, and he has been fully vaccinated. However, given his having multiple autoimmune conditions, I asked his pediatrician to complete titers to ensure that he was immune to common childhood diseases. His pediatrician suggested that we start with an MMR titer, which showed that he was not immune to measles. She subsequently ordered Hepatitis B, Varicella, and Tetanus/Diphtheria titers, which showed that he was not immune to Hepatitis B or Varicella. My son was subsequently re-immunized against the diseases to which he was not immune and as of 6 months later, follow-up titers show that he is immune. His pediatrician also consulted with an immunologist, who stated that it is fairly common for children with Down syndrome to be somewhat immunodeficient, especially when they are younger. Therefore, given that it is fairly common for children with Down syndrome to fail to mount an immune response to vaccines, has any research been conducted regarding vaccine immune response in children with Down syndrome? Also, has the American Academy of Pediatrics Council on Genetics considered including recommendations for titer testing in children with Down syndrome in the next set of guidelines? This could also become an issue with respect to COVID vaccination, given the fact that it will take some time to develop herd immunity. Therefore, I was wondering whether any thought had been given to COVID titer testing down the line. I appreciate your consideration of my question.
Answer:
The immune system of people (especially children) with Down syndrome functions differently than those without Down syndrome. Studies have shown that this is manifested by an increased susceptibility to infections,* more auto-immune diseases (conditions in which our immune system attacks tissues in our own bodies), and reduced response to vaccinations (1, 2, 3, 4, 5).**
There are limited data on the different immune response of people with Down syndrome to vaccinations and how to best manage this difference. The “Health Supervision for Children with Down Syndrome” guidelines published by the American Academy of Pediatrics recommend using the general pediatric vaccine schedule for children with Down syndrome (6). The recently published Global Down Syndrome Foundation Medical Care Guidelines for Adults with Down Syndrome did not address immunizations in the initial set of guidelines (7). An article published in 2018 recommends the same vaccine schedule for people with Down syndrome except for vaccines protecting against pneumococcal pneumonia. The authors recommended that pneumococcal vaccination be given earlier and more frequently to adults with Down syndrome (similar to adults with certain immune deficient conditions) (8). At our clinic, we recommend a schedule similar to what the article recommends for vaccines protecting against pneumococcal pneumonia (9).
At this time, there is not a recommendation by the American Academy of Pediatrics to routinely check antibody titers in children with Down syndrome to measure for immunity after receiving vaccines. Similarly, there is no recommendation to routinely check titers in adults. Drawing titers should be considered in people with or without Down syndrome with recurrent infections. The American Academy of Pediatrics has not published any information indicating that there is a pending recommendation to routinely draw titers after immunizations for children with Down syndrome. It is likely additional study would be needed before that recommendation would be added.
Vaccines are not typically studied in people with Down syndrome prior to release. Therefore, additional study is needed to improve our understanding of vaccines and their efficacy in people with Down syndrome. Similar to previous vaccines, the COVID-19 vaccines have not been studied in people with Down syndrome prior to their release. For people with Down syndrome, the Down Syndrome Medical Interest Group recommends following the same recommendations for the COVID-19 vaccine as for the whole population (11). The recent focus on the COVID-19 vaccine highlights the need for more study of vaccines in people with Down syndrome including the potential benefit of testing antibody titers after vaccination.
*There are also other factors that contribute to increased infections such as differences in the anatomy of the airway, more gastroesophageal reflux (stomach contents re-entering the esophagus and sometimes into the airway), and swallowing dysfunction.
**Not all studies show a reduced immune response to vaccines in people with Down syndrome. For example, this study (10) showed adequate immune response to pneumonia vaccine in 18 children and young adults.
Resources:
- Immune Evaluation and Vaccine Responses in Down Syndrome: Evidence of Immunodeficiency?
- Infections and Immunodeficiency in Down Syndrome
- Clinical Implications of Immune-Mediated Diseases in Children with Down Syndrome
- Immune Defect in Adults with Down Syndrome: Insights into a Complex Issue
- Influenza A/H1N1 Vaccination Response is Inadequate in Down Syndrome Children When the Latest Cut-Off Values are Used
- Health Supervision for Children with Down Syndrome
- Medical Care of Adults with Down Syndrome: A Clinical Guideline
- Importance of Vaccines in Children with Down Syndrome
- Pneumococcal Vaccine
- Functionality of the Pneumococcal Antibody Response in Down Syndrome Subjects
- DSMIG-USA COVID-19 Page