NEW ORLEANS, LA—Safety profiles among elderly people in Japan are similar for simultaneous and sequential administration of quadrivalent influenza vaccine (QIV) and 23-valent polysaccharide pneumococcal vaccine (PPV), according to an interim analysis reported at IDWeek 2016.

“Simultaneous administration of 23-valent pneumococcal vaccine and quadrivalent influenza vaccine showed an acceptable immunoresponse compared to sequential administration of the two vaccines without an increase in adverse events,” reported Kei Nakashima, MD, of the Department of Pulmonary Medicine, Kameda Medical Center, Kamogawa, in Chiba, Japan, and coauthors. “Simultaneous administration of the two vaccines may be a good strategy for improving the immunization rate.”

In Japan’s 2015–2016 influenza season, QIV replaced trivalent influenza vaccine. The research team sought to determine the immunogenicity and safety of simultaneously administering the QIV and PPV in a randomized, open-label non-inferiority study from October 2015 through August 2016.

One hundred and sixty-two adults age ≥65 years were randomly assigned to receive simultaneous injected administration (SIM group; n=81) of PPV and QIV, or sequential administration (SEQ group; n=81) of injected PPV at 2 weeks after injection of QIV.

Five participants withdrew from the SEQ study arm during the study, leaving 76 patients in that group.

H1N1, H3N2, and B Phuket-strain influenza seroprotection was not significantly different between the SIM and SEQ study groups. 

SIM group seroresponse rates were significantly lower than SEQ group seroresponse rates for serotypes 4 and 14 (odds ratio [OR] for serotype 4: 0.30; 95% CI: 0.13–0.67; P=0.003; OR for serotype 14: 0.20; 95% CI: 0.09–0.47; P<0.001), Dr. Nakashima noted. “However, the clinical impact is expected to be low because the detection of serotypes 4 and 14 has decreased in invasive pneumococcal disease and pneumonia worldwide,” he was quick to add.

There were no significant differences in adverse events between the two [SEQ and SIM] groups,” Dr. Nakashima noted.

Reported systemic reactions did not significantly differ between the two study groups. These included fever (in 2.5% of patients in SIM group and 4.2% of patients with SEQ group; P=0.668, n.s.), fatigue (11.1% and 21.1%; P=0.138, n.s.), headache (4.9% and 6.6%; P=0.740, n.s.), joint pain (13.6% and 14.5%; P=1.0, n.s.), pain of axilla (4.9% and 5.3%; P=1.0, n.s.), and rash (1.2% and 2.6%; p=0.611, n.s.). Data on fever were missing for 7 cases, however, Nakashima cautioned.

The study was funded by Merck.