Oregon researchers studying the effect of not recommending intranasal live attenuated influenza vaccines (LAIV) in favor of injected influenza vaccines (IIV) for the 2016-2017 flu season found that the change in recommendation had a minimal impact on overall flu vaccination rates, but that patients who had been given injected flu vaccine previously were slightly more likely to return for it the following season.
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Steve G. Robison, MPH, of the Immunization Program of the Oregon Health Authority in Salem, led the study to monitor the effects of the new recommendation in Oregon, where he and his coauthors noted that there is “a substantial vaccine-hesitant population” (Pediatrics. 2017 Oct 6. doi: 10.1542/peds.2017-0516).
They considered data from the state’s immunization registry, simply counting seasonal immunization rates from 2012 to 2017. As a second assessment, they compared children who had previously received LAIV between Aug. 1 and Dec. 31, 2015, and children who received IIV during the same period, to see which cohort was more likely to return for flu vaccination the following season.
“Overall, 53.1% of children in the study with previous LAIV and 56.4% with a previous IIV returned for an IIV during the 2016-2017 season,” they reported. Those rates showed that the cohort with past injected vaccine was only 1.05 times more likely to return than the cohort with past nasal spray vaccine (95% confidence interval, 1.04-1.06). The investigators also concluded that overall rates have undergone “minimal changes” in the past 5 years, and the effect of the committee’s recommendation additionally was considered to be minimal.
Mr. Robison and his associates said they had no relevant financial disclosures. The study was funded in part by the CDC’s grants to Oregon statefor immunization surveillance.