Multiple studies show that influenza vaccine is efficacious with higher efficacy demonstrated against laboratory-confirmed influenza than clinically defined outcomes.Footnote 20
In healthy children (equal to or younger than 18 or 16 years old) a systematic review and meta-analyses showed that efficacy of influenza vaccine against laboratory confirmed influenza ranged from 59% to 82%, efficacy against serologically-confirmed influenza ranged from 54% to 63% and efficacy against clinical illness ranged between 33% to 36%.from Footnote 21-to Footnote23 Other studies have shown that LAIV is more efficacious than TIV in children. NACI is reviewing data comparing efficacy of LAIV vs. TIV in older children and will publish the results when completed. Further details are available in the Flumist? statement and Appendix 1 of the 2012-2013 statement.
In a systematic review, for healthy adults, inactivated influenza vaccine efficacy against laboratory-confirmed influenza was 80% (95% CI, 56 to 91) and vaccine effectiveness against influenza-like illness was 30% (95% CI, 17 to 41) when the vaccine strain matched the circulating strains and circulation was high.Footnote 24 A recent meta-analysis identified vaccine efficacy of 50% in healthy adults (95% CI, 27 to 65) during select seasons of vaccine mismatch, although mismatch is a relative term and the amount of cross-protection is expected to vary.from Footnote 25-to Footnote27 In the elderly, vaccine effectiveness is about half of that of healthy adults and varies depending on the outcome and the study population.Footnote 28 Footnote 29 Systematic reviews have also demonstrated that influenza vaccine decreases the incidence of pneumonia, hospital admissions and deaths in the elderly,Footnote 28 and reduces exacerbations in persons with chronic obstructive pulmonary disease.Footnote 30 In observational studies, immunization has been shown to reduce the number of physician visits, hospitalizations and deaths in high-risk persons 18 to 64 years of age,Footnote 31 hospitalizations for cardiac disease and stroke in the elderly,Footnote 32 and hospitalization and deaths in persons with diabetes mellitus 18 years of age and older.Footnote 33 Observational studies that use non-specific clinical outcomes and that do not take into account differences in functional status or health-related behaviours should be interpreted with caution.from Footnote 34-to Footnote38 Vaccine efficacy may be lower in certain populations (e.g., persons with immune compromising conditions, elderly persons) than in healthy adults. However, the possibility of lower efficacy should not prevent immunization in those at high risk of influenza-associated morbidity, since vaccinated individuals are still more likely to be protected compared to those who are unvaccinated.
A recent review by Osterholm et al. on efficacy and effectiveness of influenza vaccines has been frequently referred to over the past several months.Footnote 39 In this review, the pooled efficacy of TIV in adults 18-65 years of age was 59% (95% CI, 51 to 67). The authors found no papers that met their inclusion criteria for TIV efficacy in children 2-17 years old or for adults older than 65 years. The pooled efficacy of LAIV for children 6 months to 7 years old was 83% (95% CI, 69 to 91). The authors found no papers that met their inclusion criteria for older children. Vaccine effectiveness was deemed variable according to the included data, with 35% of the analyses that were included showing significant protection against medically attended influenza. The author's conclusions in this review may be subject to interpretation because of the restrictive inclusion criteria that were used to select evidence for this review. The NACI methodology uses broader inclusion criteria for available evidence, and as such, interpretation of evidence may vary from other reviews. NACI continues to encourage high quality research on influenza vaccine efficacy and effectiveness as it constitutes critical information to make influenza immunization recommendations and is still lacking on several topics of relevance.
With the exception of LAIV, there is limited efficacy information for the newer products. While brief summaries are provided below, the individual NACI supplemental statements for Intanza?,Footnote 17 FluMist?,Footnote 18 and Fluad?Footnote 19 should be consulted for details.
http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/13vol39/acs-dcc-4/index-eng.php
In healthy children (equal to or younger than 18 or 16 years old) a systematic review and meta-analyses showed that efficacy of influenza vaccine against laboratory confirmed influenza ranged from 59% to 82%, efficacy against serologically-confirmed influenza ranged from 54% to 63% and efficacy against clinical illness ranged between 33% to 36%.from Footnote 21-to Footnote23 Other studies have shown that LAIV is more efficacious than TIV in children. NACI is reviewing data comparing efficacy of LAIV vs. TIV in older children and will publish the results when completed. Further details are available in the Flumist? statement and Appendix 1 of the 2012-2013 statement.
In a systematic review, for healthy adults, inactivated influenza vaccine efficacy against laboratory-confirmed influenza was 80% (95% CI, 56 to 91) and vaccine effectiveness against influenza-like illness was 30% (95% CI, 17 to 41) when the vaccine strain matched the circulating strains and circulation was high.Footnote 24 A recent meta-analysis identified vaccine efficacy of 50% in healthy adults (95% CI, 27 to 65) during select seasons of vaccine mismatch, although mismatch is a relative term and the amount of cross-protection is expected to vary.from Footnote 25-to Footnote27 In the elderly, vaccine effectiveness is about half of that of healthy adults and varies depending on the outcome and the study population.Footnote 28 Footnote 29 Systematic reviews have also demonstrated that influenza vaccine decreases the incidence of pneumonia, hospital admissions and deaths in the elderly,Footnote 28 and reduces exacerbations in persons with chronic obstructive pulmonary disease.Footnote 30 In observational studies, immunization has been shown to reduce the number of physician visits, hospitalizations and deaths in high-risk persons 18 to 64 years of age,Footnote 31 hospitalizations for cardiac disease and stroke in the elderly,Footnote 32 and hospitalization and deaths in persons with diabetes mellitus 18 years of age and older.Footnote 33 Observational studies that use non-specific clinical outcomes and that do not take into account differences in functional status or health-related behaviours should be interpreted with caution.from Footnote 34-to Footnote38 Vaccine efficacy may be lower in certain populations (e.g., persons with immune compromising conditions, elderly persons) than in healthy adults. However, the possibility of lower efficacy should not prevent immunization in those at high risk of influenza-associated morbidity, since vaccinated individuals are still more likely to be protected compared to those who are unvaccinated.
A recent review by Osterholm et al. on efficacy and effectiveness of influenza vaccines has been frequently referred to over the past several months.Footnote 39 In this review, the pooled efficacy of TIV in adults 18-65 years of age was 59% (95% CI, 51 to 67). The authors found no papers that met their inclusion criteria for TIV efficacy in children 2-17 years old or for adults older than 65 years. The pooled efficacy of LAIV for children 6 months to 7 years old was 83% (95% CI, 69 to 91). The authors found no papers that met their inclusion criteria for older children. Vaccine effectiveness was deemed variable according to the included data, with 35% of the analyses that were included showing significant protection against medically attended influenza. The author's conclusions in this review may be subject to interpretation because of the restrictive inclusion criteria that were used to select evidence for this review. The NACI methodology uses broader inclusion criteria for available evidence, and as such, interpretation of evidence may vary from other reviews. NACI continues to encourage high quality research on influenza vaccine efficacy and effectiveness as it constitutes critical information to make influenza immunization recommendations and is still lacking on several topics of relevance.
With the exception of LAIV, there is limited efficacy information for the newer products. While brief summaries are provided below, the individual NACI supplemental statements for Intanza?,Footnote 17 FluMist?,Footnote 18 and Fluad?Footnote 19 should be consulted for details.
http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/13vol39/acs-dcc-4/index-eng.php
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