Vaccine-associated attenuation of subjective severity among outpatients with influenza.

Influenza vaccines can mitigate illness severity, including reduced risk of ICU admission and death, in people with breakthrough infection. Less is known about vaccine attenuation of mild/moderate influenza illness. We compared subjective severity scores in vaccinated and unvaccinated persons with medically attended illness and laboratory-confirmed influenza. Participants were prospectively recruited when presenting for care at five US sites over nine seasons. Participants aged ≥ 16 years completed the EQ-5D-5L visual analog scale (VAS) at enrollment. After controlling for potential confounders in a multivariable model, including age and general health status, VAS scores were significantly higher among 2,830 vaccinated participants compared with 3,459 unvaccinated participants, indicating vaccinated participants felt better at the time of presentation for care. No differences in VAS scores were observed by the type of vaccine received among persons aged ≥ 65 years. Our findings suggest vaccine-associated attenuation of milder influenza illness is possible.
Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: ‘Dr. Gaglani reports grants from CDC outside the submitted work. Dr. McLean reports grants from Seqirus outside the submitted work. Dr. Nowalk reports grants from Merck & Co outside the submitted work. Dr. Zimmerman reports grants from Sanofi Pasteur outside the submitted work. Dr. L. Jackson reports grants from Novavax outside the submitted work. Dr. Martin reports personal fees from Pfizer outside the submitted work. All other authors have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.’
(Published by Elsevier Ltd.)