tetano
Editor, Senior Moderator
Vaccine. 2016 Dec 7. pii: S0264-410X(16)31044-1. doi: 10.1016/j.vaccine.2016.11.013. [Epub ahead of print]
[h=1]Do antibody responses to the influenza vaccine persist year-round in the elderly? A systematic review and meta-analysis.[/h] Young B[SUP]1[/SUP], Zhao X[SUP]2[/SUP], Cook AR[SUP]3[/SUP], Parry CM[SUP]4[/SUP], Wilder-Smith A[SUP]5[/SUP], I-Cheng MC[SUP]6[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] [h=4]INTRODUCTION:[/h] The influenza vaccine is less immunogenic in older than younger adults, and the duration of protection is unclear. Determining if protection persists beyond a typical seasonal epidemic is important for climates where influenza virus activity is year-round.
[h=4]METHODS:[/h] A systematic review protocol was developed and registered with PROSPERO [CRD42015023847]. Electronic databases were searched systematically for studies reporting haemagglutination-inhibition (HI) titres 180-360days following vaccination with inactivated trivalent seasonal influenza vaccine, in adults aged ⩾65years. Geometric mean titre (GMT) and seroprotection (HI titre ⩾1:40) at each time point was extracted. A Bayesian model was developed of titre trajectories from pre-vaccination to Day 360. In the meta-analysis, studies were aggregated using a random-effects model to compare pre-vaccination with post-vaccination HI titres at Day 21-42 ('seroconversion'), Day 180 and Day 360. Potential sources of bias were systematically assessed, and heterogeneity explored.
[h=4]RESULTS:[/h] 2864 articles were identified in the literature search, of which nineteen met study inclusion/exclusion criteria. Sixteen studies contained analysable data from 2565 subjects. In the Bayesian model, the proportion of subjects seroprotected increased from 41-51% pre-vaccination to 75-78% at seroconversion. Seroprotection subsequently fell below 60% for all serotypes by Day 360: A/H1 42% (95% CI 38-46), A/H3 59% (54-63), B 47% (42-52). The Bayesian model of GMT trajectories revealed a similar pattern. By Day 360, titres were similar to pre-vaccination levels. In the meta-analysis, no significant difference in proportion of subjects seroprotected, 0 (-0.11, 0.11) or in log[SUB]2[/SUB]GMT 0.30 (-0.02, 0.63) was identified by Day 360 compared with pre-vaccination. The quality of this evidence was limited to moderate on account of significant participant dropout.
[h=4]CONCLUSIONS:[/h] The review found consistent evidence that HI antibody responses following influenza vaccination do not reliably persist year-round in older adults. Alternative vaccination strategies could provide clinical benefits in regions where year-round protection is important.
Copyright ? 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.
[h=4]KEYWORDS:[/h] Elderly; Influenza; Seasonal; Seroprotection; Tropics; Vaccine
PMID: 27939013 DOI: 10.1016/j.vaccine.2016.11.013
[PubMed - as supplied by publisher]
[h=1]Do antibody responses to the influenza vaccine persist year-round in the elderly? A systematic review and meta-analysis.[/h] Young B[SUP]1[/SUP], Zhao X[SUP]2[/SUP], Cook AR[SUP]3[/SUP], Parry CM[SUP]4[/SUP], Wilder-Smith A[SUP]5[/SUP], I-Cheng MC[SUP]6[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] [h=4]INTRODUCTION:[/h] The influenza vaccine is less immunogenic in older than younger adults, and the duration of protection is unclear. Determining if protection persists beyond a typical seasonal epidemic is important for climates where influenza virus activity is year-round.
[h=4]METHODS:[/h] A systematic review protocol was developed and registered with PROSPERO [CRD42015023847]. Electronic databases were searched systematically for studies reporting haemagglutination-inhibition (HI) titres 180-360days following vaccination with inactivated trivalent seasonal influenza vaccine, in adults aged ⩾65years. Geometric mean titre (GMT) and seroprotection (HI titre ⩾1:40) at each time point was extracted. A Bayesian model was developed of titre trajectories from pre-vaccination to Day 360. In the meta-analysis, studies were aggregated using a random-effects model to compare pre-vaccination with post-vaccination HI titres at Day 21-42 ('seroconversion'), Day 180 and Day 360. Potential sources of bias were systematically assessed, and heterogeneity explored.
[h=4]RESULTS:[/h] 2864 articles were identified in the literature search, of which nineteen met study inclusion/exclusion criteria. Sixteen studies contained analysable data from 2565 subjects. In the Bayesian model, the proportion of subjects seroprotected increased from 41-51% pre-vaccination to 75-78% at seroconversion. Seroprotection subsequently fell below 60% for all serotypes by Day 360: A/H1 42% (95% CI 38-46), A/H3 59% (54-63), B 47% (42-52). The Bayesian model of GMT trajectories revealed a similar pattern. By Day 360, titres were similar to pre-vaccination levels. In the meta-analysis, no significant difference in proportion of subjects seroprotected, 0 (-0.11, 0.11) or in log[SUB]2[/SUB]GMT 0.30 (-0.02, 0.63) was identified by Day 360 compared with pre-vaccination. The quality of this evidence was limited to moderate on account of significant participant dropout.
[h=4]CONCLUSIONS:[/h] The review found consistent evidence that HI antibody responses following influenza vaccination do not reliably persist year-round in older adults. Alternative vaccination strategies could provide clinical benefits in regions where year-round protection is important.
Copyright ? 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.
[h=4]KEYWORDS:[/h] Elderly; Influenza; Seasonal; Seroprotection; Tropics; Vaccine
PMID: 27939013 DOI: 10.1016/j.vaccine.2016.11.013
[PubMed - as supplied by publisher]