tetano
Editor, Senior Moderator
Vaccine
Available online 1 March 2012
Impacts on influenza A(H1N1)pdm09 infection from cross-protection of seasonal trivalent influenza vaccines and A(H1N1)pdm09 vaccines: Systematic review and meta-analyses
Jiehui Kevin Yina, b,
Maria Yui Kwan Chowa, b,
Gulam Khandakera, b,
Catherine Kinga, b,
Peter Richmondc, d, e,
Leon Herona, b, f,
Robert Booya, b, f, Corresponding author contact information, E-mail the corresponding author
a National Centre for Immunisation Research and Surveillance, The Children's Hospital at Westmead, NSW, Australia
b Sydney Medical School, The University of Sydney, NSW, Australia
c School of Paediatrics and Child Health, University of Western Australia, WA, Australia
d Department of Paediatric and Adolescent Medicine, Princess Margaret Hospital, WA, Australia
e Vaccine Trials Group, Telethon Institute for Child Health Research, WA, Australia
f Sydney Emerging Infections and Biosecurity Institute, NSW, Australia
Received 16 September 2011. Revised 4 February 2012. Accepted 20 February 2012. Available online 1 March 2012.
http://dx.doi.org/10.1016/j.vaccine.2012.02.048,
Abstract
Cross-protection by seasonal trivalent influenza vaccines (TIVs) against pandemic influenza A H1N1 2009 (now known as A[H1N1]pdm09) infection is controversial; and the vaccine effectiveness (VE) of A(H1N1)pdm09 vaccines has important health-policy implications. Systematic reviews and meta-analyses are needed to assess the impacts of both seasonal TIVs and A(H1N1)pdm09 vaccines against A(H1N1)pdm09.We did a systematic literature search to identify observational and/or interventional studies reporting cross-protection of TIV and A(H1N1)pdm09 VE from when the pandemic started (2009) until July 2011. The studies fulfilling inclusion criteria were meta-analysed. For cross-protection and VE, respectively, we stratified by vaccine type, study design and endpoint.
Seventeen studies (104,781 subjects) and 10 studies (2,906,860 subjects), respectively, reported cross-protection of seasonal TIV and VE of A(H1N1)pdm09 vaccines; six studies (17,229 subjects) reported on both. Thirteen studies (95,903 subjects) of cross-protection, eight studies (859,461 subjects) of VE, and five studies (9,643 subjects) were meta-analysed and revealed: (1) cross-protection for confirmed illness was 19% (95% confident interval = 13?42%) based on 13 case?control studies with notable heterogeneity. A higher cross-protection of 34% (9?52%) was found in sensitivity analysis (excluding five studies with moderate/high risk of bias). Further exclusion of studies that recruited early in the pandemic (when non-recipients of TIV were more likely to have had non-pandemic influenza infection that may have been cross-protective) dramatically reduced heterogeneity. One RCT reported cross-protection of 38% (19?53%) for confirmed illness. One case?control study reported cross-protection of 50% (40?59%) against hospitalisation. (2) VE of A(H1N1)pdm09 for confirmed illness was 86% (73?93%) based on 11 case?control studies and 79% (22?94%) based on two cohort studies; VE against medically-attended ILI was 32% (8?50%) in one cohort study.
TIVs provided moderate cross-protection against both laboratory-confirmed A(H1N1)pdm09 illness (based on eight case?control studies with low risk of bias and one RCT) and also hospitalisation. A finding of increased risk from seasonal vaccine was limited to cases recruited early in the pandemic. A(H1N1)pdm09 vaccines were highly effective against confirmed A(H1N1)pdm09 illness. Although cross-protection was less than the direct effect of strain-specific vaccination against A(H1N1)pdm09, TIV was generally beneficial before A(H1N1)pdm09 vaccine was available.
Highlights
► A systematic review of cross-protection of TIVs and effectiveness of pH1N1 vaccines. ► A protective effect (34?38%) against pandemic flu was shown by TIVs. ► Early recruitment in the pandemic introduced heterogeneity. ► A effectiveness of 79?86% against pandemic flu was shown from pH1N1 vaccines.
http://www.sciencedirect.com/science/article/pii/S0264410X12002423
Available online 1 March 2012
Impacts on influenza A(H1N1)pdm09 infection from cross-protection of seasonal trivalent influenza vaccines and A(H1N1)pdm09 vaccines: Systematic review and meta-analyses
Jiehui Kevin Yina, b,
Maria Yui Kwan Chowa, b,
Gulam Khandakera, b,
Catherine Kinga, b,
Peter Richmondc, d, e,
Leon Herona, b, f,
Robert Booya, b, f, Corresponding author contact information, E-mail the corresponding author
a National Centre for Immunisation Research and Surveillance, The Children's Hospital at Westmead, NSW, Australia
b Sydney Medical School, The University of Sydney, NSW, Australia
c School of Paediatrics and Child Health, University of Western Australia, WA, Australia
d Department of Paediatric and Adolescent Medicine, Princess Margaret Hospital, WA, Australia
e Vaccine Trials Group, Telethon Institute for Child Health Research, WA, Australia
f Sydney Emerging Infections and Biosecurity Institute, NSW, Australia
Received 16 September 2011. Revised 4 February 2012. Accepted 20 February 2012. Available online 1 March 2012.
http://dx.doi.org/10.1016/j.vaccine.2012.02.048,
Abstract
Cross-protection by seasonal trivalent influenza vaccines (TIVs) against pandemic influenza A H1N1 2009 (now known as A[H1N1]pdm09) infection is controversial; and the vaccine effectiveness (VE) of A(H1N1)pdm09 vaccines has important health-policy implications. Systematic reviews and meta-analyses are needed to assess the impacts of both seasonal TIVs and A(H1N1)pdm09 vaccines against A(H1N1)pdm09.We did a systematic literature search to identify observational and/or interventional studies reporting cross-protection of TIV and A(H1N1)pdm09 VE from when the pandemic started (2009) until July 2011. The studies fulfilling inclusion criteria were meta-analysed. For cross-protection and VE, respectively, we stratified by vaccine type, study design and endpoint.
Seventeen studies (104,781 subjects) and 10 studies (2,906,860 subjects), respectively, reported cross-protection of seasonal TIV and VE of A(H1N1)pdm09 vaccines; six studies (17,229 subjects) reported on both. Thirteen studies (95,903 subjects) of cross-protection, eight studies (859,461 subjects) of VE, and five studies (9,643 subjects) were meta-analysed and revealed: (1) cross-protection for confirmed illness was 19% (95% confident interval = 13?42%) based on 13 case?control studies with notable heterogeneity. A higher cross-protection of 34% (9?52%) was found in sensitivity analysis (excluding five studies with moderate/high risk of bias). Further exclusion of studies that recruited early in the pandemic (when non-recipients of TIV were more likely to have had non-pandemic influenza infection that may have been cross-protective) dramatically reduced heterogeneity. One RCT reported cross-protection of 38% (19?53%) for confirmed illness. One case?control study reported cross-protection of 50% (40?59%) against hospitalisation. (2) VE of A(H1N1)pdm09 for confirmed illness was 86% (73?93%) based on 11 case?control studies and 79% (22?94%) based on two cohort studies; VE against medically-attended ILI was 32% (8?50%) in one cohort study.
TIVs provided moderate cross-protection against both laboratory-confirmed A(H1N1)pdm09 illness (based on eight case?control studies with low risk of bias and one RCT) and also hospitalisation. A finding of increased risk from seasonal vaccine was limited to cases recruited early in the pandemic. A(H1N1)pdm09 vaccines were highly effective against confirmed A(H1N1)pdm09 illness. Although cross-protection was less than the direct effect of strain-specific vaccination against A(H1N1)pdm09, TIV was generally beneficial before A(H1N1)pdm09 vaccine was available.
Highlights
► A systematic review of cross-protection of TIVs and effectiveness of pH1N1 vaccines. ► A protective effect (34?38%) against pandemic flu was shown by TIVs. ► Early recruitment in the pandemic introduced heterogeneity. ► A effectiveness of 79?86% against pandemic flu was shown from pH1N1 vaccines.
http://www.sciencedirect.com/science/article/pii/S0264410X12002423