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Repeated IIV may increase protection
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Repeated immunization with the inactivated influenza vaccine, or IIV, appeared to increase long-term protection against some respiratory illness episodes in children with pre-existing medical conditions, according to findings recently published in Annals of Family Medicine.
Researchers analyzed electronic health records of 4,183 children with pre-existing medical conditions to determine whether prior immunization altered the effect of IIV on primary care-diagnosed respiratory illness episodes during influenza seasons from 2004 to 2015.
Adjusted analyses showed lower odds for respiratory illness in children immunized with prior IIV vs. those without prior IIV immunization (OR = 0.61; 95% CI, 0.47-0.78 for the current year immunized and one IIV in the previous 2 years; and OR = 0.85; 95% CI, 0.68-1.07 for the current year immunized and two or more IIVs in the previous 3 years, including the prior year).
“This study shows that protection against seasonal [respiratory illness] is not attenuated after repeated annual inactivated influenza vaccine immunization in children with preexisting medical conditions. Interestingly, our findings suggest that repeated inactivated influenza vaccine immunization may even increase protection,” the researchers wrote. – by Janel Miller
- Reference:
- de Hoog MLA, et al. Ann Fam Med. 2019;doi:10.1370/afm.2340.
Disclosures: The authors report no relevant financial disclosures.
Perspective
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Kathryn Edwards, MD
In this paper, investigators from the Netherlands investigate the impact of repeated influenza vaccine in children with underlying medical conditions. There have been some data in adults that suggest that repeated influenza vaccines may not work as well if you give them repeatedly each year. This study investigates that in children.
De Hoog and colleagues took a large database of children with underlying conditions were evaluated for influenza-like illness, acute respiratory infections, and asthma. Those children that received the vaccine in multiple years were compared with those who were immunized only in that influenza season (they did not do laboratory-based studies to confirm influenza in those patients that had influenza-like illness). These researchers found there was no negative impact on the children from being immunized in earlier years, and indeed the children appeared to be better protected.
The study is reassuring but did not confirm the actual laboratory-confirmed rate of influenza, which was a limitation of the study. Primary care doctors should continue to encourage all patients and particularly high-risk patients to be immunized each year. These results should reinforce the recommended immunization guidelines.
Vanderbilt University School of Medicine
Division of Infectious Diseases
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