Seasonal influenza vaccine effectiveness against medically attended influenza illness among children aged 6–59 months, October 2011–September 2012: A matched test-negative case–control study in Suzhou, China

Wang, Yin; Zhang, Tao; Chen, Liling; Greene, Carolyn M.; Ding, Yi-min; Cheng, Yun; Yang, Chao; Zeng, Shanshan; Hua, Jing; Zhou, Suizan; Song, Ying; Luan, Lin; Zhang, Jun

doi:10.1016/j.vaccine.2016.03.056

Cited by 15 publications

(10 citation statements)

References 27 publications

(30 reference statements)

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“…Our estimates are generally consistent with previous studies that have assessed VE among young children for these four seasons ( Table 4 ), but direct comparisons are difficult due to varying healthcare settings (inpatient versus outpatient), geographical locations, and age groups studied [ 5 , 17 – 35 ]. The sole previous study of VE against laboratory-confirmed influenza hospitalizations specifically in young children aged 6–59 months reported an estimate of 75% (95%CI, –100% to 97%) for the 2012 southern hemisphere influenza season in New Zealand [ 33 ].…”

Section: Discussionsupporting

confidence: 88%

“…Assuming that VE estimates for hospitalization and outpatient outcomes should be consistent, as suggested in a recent systematic review [ 36 ], our results are remarkably similar to estimates from the United Kingdom for 2010–11 (VE = 73%; 95%CI, 53%-85% versus 72%; 95%CI, 12%-91%) and 2011–12 (VE = 54%; 95%CI, 19%-73% versus 52%; 95%CI, –446% to 96%), but our estimates had tighter confidence intervals [ 22 , 27 ]. Relaxing the age criteria to include children as old as 19 years, our estimates are congruent with estimates from North America, Europe, Asia, and Australasia for the 2010–11, 2011–12, and 2013–14 seasons [ 5 , 17 – 20 , 25 , 29 , 31 , 34 , 35 ].…”

Section: Discussionsupporting

confidence: 71%

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Vaccine effectiveness against laboratory-confirmed influenza hospitalizations among young children during the 2010-11 to 2013-14 influenza seasons in Ontario, Canada

et al. 2017

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Uncertainty remains regarding the magnitude of effectiveness of influenza vaccines for preventing serious outcomes, especially among young children. We estimated vaccine effectiveness (VE) against laboratory-confirmed influenza hospitalizations among children aged 6–59 months. We used the test-negative design in hospitalized children in Ontario, Canada during the 2010–11 to 2013–14 influenza seasons. We used logistic regression models adjusted for age, season, and time within season to calculate VE estimates by vaccination status (full vs. partial), age group, and influenza season. We also assessed VE incorporating prior history of influenza vaccination. We included specimens from 9,982 patient hospitalization episodes over four seasons, with 12.8% testing positive for influenza. We observed variation in VE by vaccination status, age group, and influenza season. For the four seasons combined, VE was 60% (95%CI, 44%-72%) for full vaccination and 39% (95%CI, 17%-56%) for partial vaccination. VE for full vaccination was 67% (95%CI, 48%-79%) for children aged 24–59 months, 48% (95%CI, 12%-69%) for children aged 6–23 months, 77% (95%CI, 47%-90%) for 2010–11, 59% (95%CI, 13%-81%) for 2011–12, 33% (95%CI, –18% to 62%) for 2012–13, and 72% (95%CI, 42%-86%) for 2013–14. VE in children aged 24–59 months appeared similar between those vaccinated in both the current and previous seasons and those vaccinated in the current season only, with the exception of 2012–13, when VE was lower for those vaccinated in the current season only. Influenza vaccination is effective in preventing pediatric laboratory-confirmed influenza hospitalizations during most seasons.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionsupporting

confidence: 71%

Vaccine effectiveness against laboratory-confirmed influenza hospitalizations among young children during the 2010-11 to 2013-14 influenza seasons in Ontario, Canada

et al. 2017

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“…Influenza causes widespread seasonal disease and vaccination has been shown to reduce illness among the population 1–4 . Several studies have demonstrated that vaccination confers protection against virologically confirmed influenza 5 .…”

Section: Introductionmentioning

confidence: 99%

Different Repeat Annual Influenza Vaccinations Improve the Antibody Response to Drifted Influenza Strains

Plant

Fredell

Hatcher³

et al. 2017

Sci Rep

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Seasonal influenza vaccine formulas change almost every year yet information about how this affects the antibody repertoire of vaccine recipients is inadequate. New vaccine virus strains are selected, replacing older strains to better match the currently circulating strains. But even while the vaccine is being manufactured the circulating strains can evolve. The ideal response to a seasonal vaccine would maintain antibodies toward existing strains that might continue to circulate, and to generate crossreactive antibodies, particularly towards conserved influenza epitopes, potentially limiting infections caused by newly evolving strains. Here we use the hemagglutination inhibition assay to analyze the antibody repertoire in subjects vaccinated two years in a row with either identical vaccine virus strains or with differing vaccine virus strains. The data indicates that changing the vaccine formulation results in an antibody repertoire that is better able to react with strains emerging after the vaccine virus strains are selected. The effect is observed for both influenza A and B strains in groups of subjects vaccinated in three different seasons. Analyses include stratification by age and sex.Influenza causes widespread seasonal disease and vaccination has been shown to reduce illness among the population [1][2][3][4] . Several studies have demonstrated that vaccination confers protection against virologically confirmed influenza 5 . However, understanding vaccination effectiveness is complicated because a large portion of the population is asymptomatically infected 6 . The circulating strains evolve from season to season leading to changes in vaccine formulation which further complicates comparisons between seasons.Vaccine effectiveness can be measured by controlled clinical trials but comparisons between trials is complicated by factors such as the prevalence of the circulating virus and the closeness of virus match each season 7 . Observational studies, used in places where universal vaccination recommendations make it unethical to perform trials with placebos, are an increasingly common way of measuring vaccine effectiveness among the general population. Test-negative studies are a widely used method but the estimates for vaccine effectiveness vary widely depending on the study design and often have overlapping confidence intervals [8][9][10] . Correlates of protection, such as the hemagglutination inhibition (HI) titer, are widely used to assess vaccine efficacy. HI titers are associated with reduced risk of disease but there is significant variation in the protective titer depending on factors such as the age of the recipient and the severity of the influenza season [11][12][13] . It has also been reported that factors not detected in HI assays are associated with reduced risk of infection 14,15 .Changes in the annual vaccine formulation are compelled by the antigenic drift associated with seasonal influenza viruses. Despite the best efforts of a group of experts in selecting the candidate vaccine virus (CV...

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“…5 Prior studies conducted in China have shown moderate influenza vaccine effectiveness (VE) against laboratory-confirmed influenza illness in young children. [6][7][8][9][10] However, VE varies each season due to changes in vaccine components and their antigenic match to dominant circulating strains, highlighting the value of annual VE monitoring to estimate the health impact of influenza vaccination. [6][7][8][9][10][11][12] In China, the current national pharmacopeia, which serves as a guideline for instructions on domestic vaccine package inserts, recommends administering two doses of seasonal influenza vaccine of 0.25 ml containing 7.5 μg hemagglutinin for each virus strain per dose for children aged 6-35 months who have never received influenza vaccine before, and only one dose of 0.5 ml containing 15 μg hemagglutinin for each virus strain for children aged ≥3 years, regardless of prior vaccine receipt.…”

Section: Introductionmentioning

confidence: 99%

Dose effect of influenza vaccine on protection against laboratory-confirmed influenza illness among children aged 6 months to 8 years of age in southern China, 2013/14–2015/16 seasons: a matched case–control study

Greene

et al. 2019

Human Vaccines & Immunotherapeutics

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Background We conducted a matched case-control study in China during the 2013/14-2015/16 influenza seasons to estimate influenza vaccine effectiveness (VE) by dose among children aged 6 months to 8 years. Methods Cases were laboratory-confirmed influenza infections identified through the influenza-like illness sentinel surveillance network in Guangzhou. Age-and sex-matched community controls were randomly selected through the expanded immunization program database. We defined priming as receipt of ≥1 dose of influenza vaccine during the immediate prior season. Results In total, 4,185 case-control pairs were analyzed. Among children 6-35 months, VE for current season dose(s) across the three seasons during 2013/14-2015/16 were 59% (95% Confidence Interval: 44-71%), 12% (−11%,30%), 54% (32-69%); among unprimed children 6-35 months, VE for 1 vs 2 current season doses were 45% (8-67%) vs 65% (46-78%), −2% (−53%,32%) vs 19% (−11%,40%), and 37% (−24%,68%) vs 61% (32-78%). Among children aged 3-8 years, VE for current season dose(s) across study seasons were 62% (36-78%), 43% (22-58%), 32% (1-53%). VE for unprimed children receiving 1 dose only in current season was insignificant or lower than among all children. Conclusion Findings support utility of providing second dose ("booster dose") of seasonal influenza vaccine to unprimed children aged 6-35 months, and the need to study further dose effect of a booster dose among unprimed children aged 3-8 years in China.

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Seasonal influenza vaccine effectiveness against medically attended influenza illness among children aged 6–59 months, October 2011–September 2012: A matched test-negative case–control study in Suzhou, China

Cited by 15 publications

References 27 publications

Vaccine effectiveness against laboratory-confirmed influenza hospitalizations among young children during the 2010-11 to 2013-14 influenza seasons in Ontario, Canada

Vaccine effectiveness against laboratory-confirmed influenza hospitalizations among young children during the 2010-11 to 2013-14 influenza seasons in Ontario, Canada

Different Repeat Annual Influenza Vaccinations Improve the Antibody Response to Drifted Influenza Strains

Dose effect of influenza vaccine on protection against laboratory-confirmed influenza illness among children aged 6 months to 8 years of age in southern China, 2013/14–2015/16 seasons: a matched case–control study

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