@article{fdi:010096063,
  title = {{H}ousehold {SARS}-{C}o{V}-2 transmission during {O}micron wave in {C}hiang {M}ai, {T}hailand : a prospective observational study},
  author = {{K}hamduang, {W}. and {S}uebtam, {P}. and {C}ollins, {I}. {J}. and {S}ripan, {P}. and {C}halom, {K}. and {H}ongjaisee, {S}. and {K}ham-{K}jing, {N}. and {W}angsaeng, {N}. and {I}nmonthian, {P}. and {P}inasu, {A}. and {K}ohklang, {N}. and {A}rnal, {M}athis and {S}pyer, {M}. and {S}teffens-{W}esterhof, {I}. and {A}ramrattana, {A}. and {L}allemant, {M}arc and {A}ngkurawaranon, {C}. and {B}ruijning-{V}erhagen, {P}. and {N}go-{G}iang-{H}uong, {N}icole and {T}hailand {V}erdi-{R}ecover {S}tudy {T}eam,},
  editor = {},
  language = {{ENG}},
  abstract = {{B}ackground {SARS}-{C}o{V}-2 transmission studies involving children in {T}hailand have been relatively limited to the early waves with the alpha and delta variants. {O}ur study aims to address these gaps by examining household transmission in {C}hiang {M}ai, northern {T}hailand, during the {O}micron wave in a post vaccination period. {M}ethods {T}his prospective observational study enrolled households comprising a confirmed {COVID}-19 index patient with at least one uninfected contact and a child (<18 years of age who maybe an index or contact). {P}articipant data, nasopharyngeal swabs, and blood samples were collected at entry and final visit. {P}articipants recorded daily symptoms for 21 days and self-administered {SARS}-{C}o{V}-2 antigen tests every other day for 14 days. {I}ncident infections were confirmed by {RT}-{PCR}. {S}econdary attack rates ({SAR}s) were calculated and associated factors were analyzed using multivariable generalized estimating equations models. {P}hylogenetic analysis was used to confirm intra-household transmission.<br /> {F}indings {F}rom {J}uly 2022 to {M}ay 2024, 93 households (93 index cases, 197 contacts) were enrolled; 52% of index cases and 49% of contacts were <18 years. {A}mong contacts, despite 89% (175/197) having received the {SARS}-{C}o{V}-2 vaccine (of whom 75% > 6 months prior), 44 became infected, yielding a household {SAR} of 33% (95% {CI}: 24-44). {I}n phylogenetically-confirmed transmission, {SAR} was 25% (95% {CI}: 17-35). {I}ndex low viral load (a{RR}: 0.82, 95% {CI}: 0.74-0.92) and contacts baseline anti-{NCP} {I}g{G} positivity (a{RR}: 0.42, 95% {CI}: 0.22-0.83) were significantly associated with lower household transmission.<br /> {I}nterpretation {D}espite widespread vaccination, household transmission of {SARS}-{C}o{V}-2 remained common. {P}rior immunity in contacts and lower viral load in index cases reduced risk. {T}hese findings underscore the central role of households in ongoing spread and highlight the value of booster vaccination and genomic surveillance to clarify transmission pathways and inform prevention policies.},
  keywords = {{SARS}-{C}o{V}-2 ; {H}ousehold transmission ; {O}micron variant ; {A}nti-{NCP} {I}g{G} ; {W}hole-genome sequencing ; {T}hailand ; {C}hildren ; {THAILANDE} ; {CHIANG} {MAI}},
  booktitle = {},
  journal = {{L}ancet {R}egional {H}ealth : {S}outheast {A}sia},
  volume = {44},
  numero = {},
  pages = {100711 [11 p.]},
  ISSN = {2772-3682},
  year = {2026},
  DOI = {10.1016/j.lansea.2025.100711},
  URL = {https://www.documentation.ird.fr/hor/fdi:010096063},
}