Increasing Age, Immunosuppression Associated With Less Protection By Influenza Vaccine

Indoor shot of vaccine test samples – with reflections of glass vials and syringe
Study authors evaluated influenza-vaccinated patients hospitalized with an influenza-like illness to identify characteristics associated with being at increased risk for hospitalization with influenza.

Instance of influenza vaccination failure was increased among older individuals or immunocompromised patients, according to findings from a cohort study published in the Journal of Infectious Diseases.

Patients (N=1236) hospitalized for possible influenza-associated illnesses at 3 participating centers between the 2015 to 2019 influenza seasons were included. Vaccination status and clinical outcomes were assessed through medical records.

Patients who tested positive (n=235) or negative (n=1001) for influenza differed significantly by age (P =.02), immunosuppression status (P =.01), use of immunosuppressant medication (P =.01), and morbid obesity (P =.04), respectively.

Risk for influenza infection despite evidence of vaccination (n=235) was associated with immunosuppressed status (odds ratio [OR], 1.56; 95% CI, 1.15-2.12; P =.004) and increased age (40-65 years; OR, 1.47; 95% CI, 1.03-2.10; P =.049). Risk for infection was also associated among self-reported vaccination recipients (n=144) who were older (OR, 1.66; 95% CI, 1.16-2.39; P =.01).

Influenza A/H1N1 infected 86.7% of patients during the 2015 to 2016 season. Influenza A/H3N2 was the prominent strain in the following 3 seasons, peaking at 77.1% during 2016-2017. Influenza B infections peaked during the 2017 to 2018 season (31.3%) and was lowest during 2018 to 2019 (1.4%).

Symptom onset was increased with time from vaccination among patients positive for influenza B (138 days) compared with A/H1N1 (122.5 days; P <.01) or A/H3N2 (113 days; P <.01).

Patients who were immunosuppressed were at increased risk for infection with A/H3N2 (OR, 1.86; 95% CI, 1.25-2.75).

This study may have been underpowered to detect specifics of the A/H1N1 and influenza B subtypes due to low infection rates compared with A/H3N2.

The study authors concluded that patients who were immunocompromised or at advanced aged remained at higher risk for influenza infection regardless of vaccination status. These data suggested more effective influenza vaccines are needed in addition to improved pharmacologic prophylaxis.

Disclosure: An author declared affiliations with industry. Please refer to the original article for a full list of disclosures.


Kimball J, Zhu Y, Wyatt D, Trabue CH, Talbot KH. Influenza Vaccine Failure Associated with Age and Immunosuppression. J Infect Dis. 2020;jiaa757. doi:10.1093/infdis/jiaa757.