{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T20:19:30Z","timestamp":1790194770532,"version":"4.1.0"},"reference-count":23,"publisher":"BMJ","issue":"10","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Open"],"accepted":{"date-parts":[[2019,9,17]]},"published-print":{"date-parts":[[2019,10]]},"abstract":"<jats:sec>\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>In Guinea-Bissau, West Africa, we observed that having a smallpox vaccination scar was associated with lower HIV-1 prevalence, more strongly for women than men. If this represents a causal effect, the female\/male HIV-1 prevalence ratio would increase for birth cohorts no longer receiving smallpox vaccination due to the phase-out of this vaccine.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Design<\/jats:title>\n                    <jats:p>An ecological design using HIV surveys and information about smallpox vaccination coverage.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Setting<\/jats:title>\n                    <jats:p>Urban and rural Guinea-Bissau.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Participants<\/jats:title>\n                    <jats:p>Participants in HIV surveys were grouped into an age group with decreasing smallpox vaccination coverage (15\u201334 years) and an age group with steady smallpox vaccination coverage (\u226535 years).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Interventions<\/jats:title>\n                    <jats:p>The exposure of interest was the phase-out of the smallpox vaccine in Guinea-Bissau.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Primary and secondary outcome measures<\/jats:title>\n                    <jats:p>HIV-1 prevalence.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>At both sites, the female\/male HIV-1 prevalence ratio increased by calendar time for the age group with decreasing smallpox vaccination coverage; the combined female\/male HIV-1 prevalence ratio among people aged 15\u201334 years was 1.00 (95% CI 0.17 to 5.99) in 1987\u20131990, 1.16 (95% CI 0.69 to 1.93) in 1996\u20131997, 2.32 (95% CI 1.51 to 3.56) in 2006\u20132007 (p value for no trend=0.04). There was no increase in the female-to-male HIV-1 prevalence ratio for the age group &gt;35 years with steady smallpox vaccination coverage; 1.93 (95% CI 0.40 to 9.25) in 1987\u20131990, 1.32 (95% CI 0.83 to 2.10) in 1996\u20131997, 0.81 (95% CI 0.56 to 1.16) in 2006\u20132007 (p value for no trend=0.07).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Thus, data was compatible with the deduction that the phase-out of smallpox vaccination may have increased the susceptibility to HIV-1 relatively more for women than men. Hence, phasing out smallpox vaccination may have contributed to the global increase in the female\/male HIV-1 prevalence ratio among young individuals. Due to the potential fallacies of ecological studies, the results should be interpreted carefully, and this hypothesis needs further assessment. If the hypothesis is true, studies of smallpox vaccination could inform HIV-1 vaccine research.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/bmjopen-2019-031415","type":"journal-article","created":{"date-parts":[[2019,10,30]],"date-time":"2019-10-30T10:25:18Z","timestamp":1572431118000},"page":"e031415","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":8,"title":["Phase-out of smallpox vaccination and the female\/male HIV-1 prevalence ratio: an ecological study from Guinea-Bissau"],"prefix":"10.1136","volume":"9","author":[{"given":"Andreas","family":"Rieckmann","sequence":"first","affiliation":[{"name":"Bandim Health Project, OPEN, Department of Clinical Research, University of Southern Denmark\/Odense University Hospital, Odense, Denmark"},{"name":"Research Center for Vitamins and Vaccines (CVIVA), Bandim Health Project, Statens Serum Institut, Copenhagen, Denmark"},{"name":"Section of Epidemiology, Department of Public Health, University of Copenhagen, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8454-4686","authenticated-orcid":false,"given":"Marie","family":"Villumsen","sequence":"additional","affiliation":[{"name":"Center for Clinical Research and Prevention, Bispebjerg and Frederiksberg Hospital, Capital Region, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bo Langhoff","family":"H\u00f8nge","sequence":"additional","affiliation":[{"name":"Department of Infectious Diseases, Aarhus University Hospital, Aarhus, Denmark"},{"name":"Bandim Health Project, Indepth Network, Bissau, Guinea-Bissau"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Signe","family":"S\u00f8rup","sequence":"additional","affiliation":[{"name":"Bandim Health Project, OPEN, Department of Clinical Research, University of Southern Denmark\/Odense University Hospital, Odense, Denmark"},{"name":"Research Center for Vitamins and Vaccines (CVIVA), Bandim Health Project, Statens Serum Institut, Copenhagen, Denmark"},{"name":"Department of Clinical Epidemiology, Aarhus University, Aarhus, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Amabelia","family":"Rodrigues","sequence":"additional","affiliation":[{"name":"Bandim Health Project, Indepth Network, Bissau, Guinea-Bissau"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zacarias Jose","family":"da Silva","sequence":"additional","affiliation":[{"name":"National Institute of Public Health (INASA), Bissau, Guinea-Bissau"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hilton","family":"Whittle","sequence":"additional","affiliation":[{"name":"London School of Hygiene and Tropical Medicine, London, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6102-3810","authenticated-orcid":false,"given":"Christine","family":"Benn","sequence":"additional","affiliation":[{"name":"Bandim Health Project, OPEN, Department of Clinical Research, University of Southern Denmark\/Odense University Hospital, Odense, Denmark"},{"name":"Research Center for Vitamins and Vaccines (CVIVA), Bandim Health Project, Statens Serum Institut, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peter","family":"Aaby","sequence":"additional","affiliation":[{"name":"Bandim Health Project, Indepth Network, Bissau, Guinea-Bissau"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2019,10,30]]},"reference":[{"key":"2025121512211620000_9.10.e031415.1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1439-0450.2004.00763.x"},{"key":"2025121512211620000_9.10.e031415.2","doi-asserted-by":"crossref","DOI":"10.1186\/1471-2172-11-23","article-title":"Significantly reduced CCR5-tropic HIV-1 replication in vitro in cells from subjects previously immunized with vaccinia virus","volume":"11","author":"Weinstein","year":"2010","journal-title":"BMC Immunol"},{"key":"2025121512211620000_9.10.e031415.3","doi-asserted-by":"crossref","unstructured":"Rieckmann A , Villumsen M , Jensen ML , et al . The effect of smallpox and BCG vaccination on the risk of HIV-1 infection in Guinea-Bissau and Denmark. Open Forum Infect Dis 2017;4.","DOI":"10.1093\/ofid\/ofx130"},{"key":"2025121512211620000_9.10.e031415.4","doi-asserted-by":"publisher","DOI":"10.1097\/QAD.0b013e328300a33d"},{"key":"2025121512211620000_9.10.e031415.5","doi-asserted-by":"crossref","first-page":"640","DOI":"10.1097\/QAI.0b013e3181bf1a25","article-title":"Two distinct epidemics: the rise of HIV-1 and decline of HIV-2 infection between 1990 and 2007 in rural Guinea-Bissau","volume":"53","author":"Tienen","year":"2010","journal-title":"J Acquir Immune Defic Syndr"},{"key":"2025121512211620000_9.10.e031415.6","doi-asserted-by":"crossref","unstructured":"Rieckmann A , Villumsen M , Jensen ML , et al . The effect of smallpox and Bacillus Calmette-Gu\u00e9rin vaccination on the risk of human immunodeficiency virus-1 infection in Guinea-Bissau and Denmark. 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