The Advisory Committee on Immunization Practices (ACIP) said the high-dose inactivated (HD-IIV3) and adjuvanted inactivated (allV3) influenza vaccines are acceptable options for vaccinating solid-organ transplant (SOT) recipients ages 18 to 64 years against influenza.
Before this change, this recommendation was only made for SOT patients who were 65 and older.
During the past decade, the number of solid=organ transplants has been increasing steadily with more than 46,632 people receiving a transplant in 2023; most were between 18 and 64 years old.
Recipients are vulnerable to influenza. In a five-year cohort of SOT recipients with influenza, 69% were hospitalized, according to Lisa Grohskopf, MD, MPH, a medical officer in the Influenza Division of the CDC.
Previously, the ACIP recommended SOT recipients should receive an age-appropriate inactivated or recombinant influenza vaccine (i.e., an IIV or RIV). Live-attenuated influenza vaccine (LAIV) is not recommended for immunocompromised people because immunosuppressive regimens could diminish the immune response to the vaccine. High-dose (HD-IIV) and adjuvanted (aIIV) inactivated influenza vaccines have not been studied in SOT recipients; however, the American Society for Transplantation (AST) states that high-dose or boosted dosing might be preferable after SOT.
There was a concern that without an explicit ACIP recommendation, health insurance might not cover giving these vaccines to people younger than 65 years.
The certainty of evidence for benefits of aIIV3 and HD-IIV3 influenza vaccines is low, according to Dr. Grohskopf. There are no significant differences in influenza-associated hospitalizations or laboratory-confirmed influenza between these vaccines and the standard-dose (SD-IIV) vaccine. However, there is some evidence of improved immunogenicity for both aIIV3 and HD-IIV3 compared with the standard vaccine.
Regarding harms, the certainty of evidence is moderate. There is no significant difference in the risk for rejection of the organ between aIIV3 and HD-IIV3 versus SD-IIV vaccines. There are no data about neuroinflammatory or other immune-mediated adverse events.
No direct evidence was identified reflecting values or preferences for specific influenza vaccine types among SOT recipients, although there might be a healthcare provider preference for HD-IIV3 vaccines. The acceptance of HD-IIV3 vaccines may be limited among healthcare and public health systems, as well as insurers, due to the need for changes in standing orders, immunization information systems and electronic health record platforms.
Additionally, HD-IIV3 and adjuvanted vaccines are more expensive than unadjuvanted ones. But the intervention is probably a reasonable and efficient allocation of resources, according to Dr. Grohskopf.
Among Medicare beneficiaries ages 65 and older, white patients are more likely than Black, Asian or Hispanic individuals to use HD-IIV3.
“Transplant patients suffer from a lack of protection from standard-dose vaccines. If we voted in favor, it would enhance equity and protection for this vulnerable population. Almost all phase 3 vaccine studies automatically exclude immunocompromised patients,” said Camille Nelson Kotton, MD, FIDSA, FAST, the clinical director of Transplant and Immunocompromised Host Infectious Diseases, Infectious Diseases Division at Massachusetts General Hospital, in Boston, before the vote.
“In the most recent survey data from the CDC, it’s estimated that 7% of the U.S. population is immunocompromised. I think it’s time we think hard about how to include these patients in studies, and we have appropriate levels of information. These patients who are the most vulnerable to infection are automatically excluded from trials,” added Dr. Cotton, who is an ACIP voting member and an associate professor of medicine at Harvard Medical School, in Boston.
In addition, the ACIP recommended routine seasonal influenza vaccination for all people ages 6 months and older without contraindications. This season’s vaccine will not contain B/Yamagata because wild-type B/Yamagata viruses are no longer circulating.
U.S. influenza vaccine composition for 2024-2025 is:
- A/Victoria/4897/2022 (H1N1)pdm09-like virus for egg-based vaccines or an A/Wisconsin/67/2022 (H1N1)pdm09-like virus for cell and recombinant vaccines;
- A/Thailand/8/2022 (H3N2)-like virus for egg-based vaccines
or an A/Massachusetts/18/2022 (H3N2)-like virus for cell and recombinant vaccines; and - A B/Austria/1359417/2021 (B/Victoria lineage)-like virus.
More than 158 million doses of influenza vaccine were distributed during the 2023-2024 flu season, according to Dr. Grohskopf.
—Norah Chinn and Marie Rosenthal, MS