Vaccination, prophylaxis recommended for children with primary immunodeficiencies

Key takeaways:

• Two doses of PPSV23 5 years apart are recommended.
• Stratifying T-cell deficiencies can help ensure safe vaccinations.
• Antibiotics should be considered when upper respiratory infection symptoms appear.

WASHINGTON — Children with primary immunodeficiencies should receive routine inactive vaccinations and other prophylactic treatment, according to a presentation at the American Academy of Allergy, Asthma & Immunology Annual Meeting.

“That’s a no brainer,” Kelli W. Williams, MD, MPH, associate professor of pediatrics, Medical University of South Carolina, said during her presentation.

Affected children aged 2 to 18 years should receive two doses of pneumococcal polysaccharide vaccine or PPSV23 (Pneumovax 23; Merck), with the first at least 8 weeks after the first dose of pneumococcal conjugate vaccine (Prevnar 20; Pfizer) and the second 5 years later, Williams said.

Kelli W. Williams

Children should be evaluated before receiving these vaccines, Williams said.

“Do we think they have T-cell deficiency?” Williams said. “Is it mild, significant or severe?”

Stratifying T-cell deficiency also may aid in the safety of live vaccination, Williams said, and may stratify the risk for infections. Physicians can conduct TREC assays and assess T-cell quality before vaccination as well, she continued.

“This allows us to quantify their diagnosis,” Williams said.

Specifically, Williams said children with 22q11.2 deletion syndrome should get live administration of the mumps, measles and rubella vaccine and the varicella vaccine at age 12 months if they have CD4 counts of 400 cells/mm³ or higher, CD8 counts of 200 cells/mm³ or higher and three doses of the tetanus IgG protective vaccine.

Also, these children should receive these vaccines if their CD45RA⁺CD3⁺/4⁺ percentage is higher than their CD45RO⁺CD3⁺/4⁺ percentage in their earliest assessment, Williams said.

“Patients should meet all four of these criteria,” Williams said.

If T-cell numbers are abnormal, Williams continued, physicians should consider confirming normal TREC assay results from newborn screenings or flow cytometry confirming recent thymic emigrants (RTEs).

Williams also noted that either marker of RTEs can help physicians confirm adequate thymic function and rule out most causes of severe combined immunodeficiency when they are available.

“Some may require immunoglobulin replacement,” Williams said. “That’s important for you to understand.”

Absolute indications for immunoglobulin replacement include complete athymia and common variable immunodeficiency in association with 22q11.2 deletion syndrome, Williams said.

Physicians also should consider prophylactic antibiotics for patients who have recurrent bacterial sinopulmonary infections, with trimethoprim/sulfamethoxazole recommended in particular, Williams said.

When symptoms of upper respiratory infection develop, Williams additionally said that physicians should consider using antibiotics early.

“We’re not getting them to have worse lungs later in life,” Williams said.

Patients with 22q11.2 deletion syndrome have lower rates of opportunistic infections except for congenital athymia compared with patients with HIV, Williams said, so they can tolerate lower CD4 counts before they need prophylaxis for pneumocystis jirovecii pneumonia.

Finally, Williams said that physicians should consider prophylaxis for mycobacterium avium complex with azithromycin for patients with congenital athymia, with or without 22q11.2 deletion syndrome.

“Starting them on azithromycin,” Williams said, “is very important.”

For more information:

Kelli W. Williams, MD, MPH, can be reached at williamske@musc.edu.