@article{fdi:010054208,
  title = {{P}andemic {I}nfluenza due to p{H}1{N}1/2009 {V}irus : estimation of infection burden in {R}eunion {I}sland through a prospective serosurvey, {A}ustral {W}inter 2009},
  author = {{D}ellagi, {K}oussay and {R}ollot, {O}. and {T}emmam, {S}. and {S}alez, {N}. and {G}uernier, {V}anina and {P}ascalis, {H}erv{\'e} and {G}erardin, {P}. and {F}ianu, {A}. and {L}apidus, {N}. and {N}aty, {N}. and {T}ortosa, {P}. and {B}oussaid, {K}. and {J}affar-{B}anjee, {M}. {C}. and {F}illeul, {L}. and {F}lahault, {A}. and {C}arrat, {F}. and {F}avier, {F}. and de {L}amballerie, {X}avier},
  editor = {},
  language = {{ENG}},
  abstract = {{B}ackground: {T}o date, there is little information that reflects the true extent of spread of the p{H}1{N}1/2009v influenza pandemic at the community level as infection often results in mild or no clinical symptoms. {T}his study aimed at assessing through a prospective study, the attack rate of p{H}1{N}1/2009 virus in {R}eunion {I}sland and risk factors of infection, during the 2009 season. {M}ethodology/{P}rincipal {F}indings: {A} serosurvey was conducted during the 2009 austral winter, in the frame of a prospective population study. {P}airs of sera were collected from 1687 individuals belonging to 772 households, during and after passage of the pandemic wave. {A}ntibodies to p{H}1{N}1/2009v were titered using the hemagglutination inhibition assay ({HIA}) with titers >= 1/40 being considered positive. {S}eroprevalence during the first two weeks of detection of p{H}1{N}1/2009v in {R}eunion {I}sland was 29.8% in people under 20 years of age, 35.6% in adults (20-59 years) and 73.3% in the elderly (>= 60 years) ({P}<0.0001). {B}aseline corrected cumulative incidence rates, were 42.9%, 13.9% and 0% in these age groups respectively ({P}<0.0001). {A} significant decline in antibody titers occurred soon after the passage of the epidemic wave. {S}eroconversion rates to p{H}1{N}1/2009 correlated negatively with age: 63.2%, 39.4% and 16.7%, in each age group respectively ({P}<0.0001). {S}eroconversion occurred in 65.2% of individuals who were seronegative at inclusion compared to 6.8% in those who were initially seropositive. {C}onclusions: {S}eroincidence of p{H}1{N}1/2009v infection was three times that estimated from clinical surveillance, indicating that almost two thirds of infections occurring at the community level have escaped medical detection. {P}eople under 20 years of age were the most affected group. {P}re-epidemic titers >= 1/40 prevented seroconversion and are likely protective against infection. {A} concern was raised about the long term stability of the antibody responses.},
  keywords = {{REUNION}},
  booktitle = {},
  journal = {{P}los {O}ne},
  volume = {6},
  numero = {9},
  pages = {e25738},
  ISSN = {1932-6203},
  year = {2011},
  DOI = {10.1371/journal.pone.0025738},
  URL = {https://www.documentation.ird.fr/hor/fdi:010054208},
}