Seasonal Effectiveness of Live Attenuated and Inactivated Influenza Vaccine

Abstract

BACKGROUND Few observational studies have evaluated the relative effectiveness of live attenuated (LAIV) and inactivated (IIV) influenza vaccines against medically attended laboratory-confirmed influenza. METHODS We analyzed US Influenza Vaccine Effectiveness Network data from participants aged 2 to 17 years during 4 seasons (2010–2011 through 2013–2014) to compare relative effectiveness of LAIV and IIV against influenza-associated illness. Vaccine receipt was confirmed via provider/electronic medical records or immunization registry. We calculated the ratio (odds) of influenza-positive to influenza-negative participants among those age-appropriately vaccinated with either LAIV or IIV for the corresponding season. We examined relative effectiveness of LAIV and IIV by using adjusted odds ratios (ORs) and 95% confidence intervals (CIs) from logistic regression. RESULTS Of 6819 participants aged 2 to 17 years, 2703 were age-appropriately vaccinated with LAIV (n = 637) or IIV (n = 2066). Odds of influenza were similar for LAIV and IIV recipients during 3 seasons (2010–2011 through 2012–2013). In 2013–2014, odds of influenza were significantly higher among LAIV recipients compared with IIV recipients 2 to 8 years old (OR 5.36; 95% CI, 2.37 to 12.13). Participants vaccinated with LAIV or IIV had similar odds of illness associated with influenza A/H3N2 or B. LAIV recipients had greater odds of illness due to influenza A/H1N1pdm09 in 2 seasons: 2010 to 2011 (OR 5.53; 95% CI, 1.35 to 22.76) and 2013–2014 (OR 2.65; 95% CI, 1.34 to 5.27). CONCLUSIONS We observed lower effectiveness of LAIV compared with IIV against influenza A/H1N1pdm09 but not A(H3N2) or B among children and adolescents, suggesting poor performance related to the LAIV A/H1N1pdm09 viral construct.

Protection of children against influenza: Emerging problems

“…53,54 In the UK, health authorities that had previously recommended IIV only for the prevention of influenza in at-risk children planned to initiate a universal childhood influenza vaccination program using LAIV because of its efficacy, safety and easy administration. 56 As expected, LAIV efficacy estimates carried out in the USA during the 3 influenza seasons from 2010-2011 to 2012-2013 evidenced that the vaccine provided statistically significant protection with a reduction of medically attended, laboratory-confirmed influenza illness. 57 Influenza occurrence, independent of the viral strain, was similar for participants vaccinated with LAIV or IIV.…”

2014–2015 Influenza Vaccine Effectiveness in the United States by Vaccine Type

“…LAIV had low VE in 2013-2014 [3,17,18], possibly due to the heat instability of the A/H1N1 [19,20] construct, which was changed for the 2015-2016 vaccine. A review of LAIV VE over several past years of the US Flu VE Network also failed to find superiority of LAIV [21]. While LAIV has been reported to have higher VE than IIV during drift seasons [22], LAIV and IIV VE did not differ statistically among children aged 2-8 years in the 2014-2015 season.…”

Summary of the NACI Statement on Seasonal Influenza Vaccine for 2017–2018

“…Data on LAIV vaccine effectiveness in children and adolescents were obtained primarily from American studies using the test-negative design: the United States Influenza Vaccine Effectiveness Network (US Flu VE Network) (2010-2016) (11)(12)(13)(14), the Influenza Clinical Investigation for Children (ICICLE) study (27). These studies used the test-negative design (21)(22)(23)(24)(25)(26), with one prospective cohort study (27) and two cluster randomized trials (28,29).…”