Immunogenicity of High-Dose vs. MF59-adjuvanted vs. Standard Influenza Vaccine in Solid Organ Transplant Recipients: The STOP-FLU trial.

BACKGROUND

The immunogenicity of the standard influenza vaccine is reduced in solid-organ transplant (SOT) recipients, so that new vaccination strategies are needed in this population.

METHODS

Adult SOT recipients from nine transplant clinics in Switzerland and Spain were enrolled if they were >3 months after transplantation. High, with stratification by organ and time from transplant. The primary outcome was vaccine response rate, defined as a ≥4-fold increase of hemagglutination-inhibition titers to at least one vaccine strain at 28 days post-vaccination. Secondary outcomes included PCR-confirmed influenza and vaccine reactogenicity.

RESULTS

619 patients were randomized, 616 received the assigned vaccines, and 598 had serum available for analysis of the primary endpoint (standard, n=198; MF59-adjuvanted, n=205; high-dose, n=195 patients). Vaccine response rates were 42% (84/198) in the standard vaccine group, 60% (122/205) in the MF59-adjuvanted vaccine group, and 66% (129/195) in the high-dose vaccine group (difference in intervention vaccines vs. standard vaccine, 0.20 [97.5% CI 0.12-1]; p<0.001; difference in high-dose vs. standard vaccine, 0.24 [95% CI 0.16-1]; p<0.001; difference in MF59-adjuvanted vs. standard vaccine, 0.17 [97.5% CI 0.08-1]; p<0.001). Influenza occurred in 6% the standard, 5% in the MF59-adjuvanted, and 7% in the high-dose vaccine groups. Vaccine-related adverse events occurred more frequently in the intervention vaccine groups, but most of the events were mild.

CONCLUSIONS

In SOT recipients, use of an MF59-adjuvanted or a high-dose influenza vaccine was safe and resulted in a higher vaccine response rate.

TRIAL REGISTRATION

Clinicaltrials.gov NCT03699839.