{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,12]],"date-time":"2026-05-12T18:09:11Z","timestamp":1778609351278,"version":"3.51.4"},"reference-count":23,"publisher":"Public Library of Science (PLoS)","issue":"5","license":[{"start":{"date-parts":[[2026,5,12]],"date-time":"2026-05-12T00:00:00Z","timestamp":1778544000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.plosglobalpublichealth.org"],"crossmark-restriction":false},"short-container-title":["PLOS Glob Public Health"],"abstract":"<jats:p>The COVID-19 pandemic has significantly affected Albania, with over 319959 cases and 3625 deaths by December 2023. Despite a national vaccination campaign initiated in January 2021, only 44.1% of the eligible population had completed the full vaccination regimen by late 2023. In this study, we aim to estimate the effectiveness of COVID-19 vaccines in preventing severe outcomes and in assessing association of prior SARS-CoV-2 infection among adults hospitalized with COVID-19 in Albania. A test-negative case-control study was conducted using SARI sentinel surveillance data from July 2022 to July 2023. The study included 1858 hospitalized SARI patients aged 18 and older, with 410 testing positive for SARS-CoV-2 (cases) and 1448 testing negative (controls). Vaccine effectiveness was calculated using logistic regression, adjusting for age, sex, comorbidities, and hospital stay duration. The overall adjusted vaccine effectiveness (VE) for preventing hospitalization was 30.1% for those fully vaccinated with two doses and 31.4% for those with a booster. VE against severe outcomes was 30.6%, increasing to 37.8% after a booster. The highest VE was observed in patients aged 80 and above, reaching 52.5% after a booster. Prior SARS-CoV-2 infection combined with vaccination was associated with higher VE to 76.2%. However, many VE estimates had wide confidence intervals overlapping zero, indicating considerable uncertainty and lack of statistical significance in some subgroup results. This study provides real-world evidence of an association between COVID-19 vaccination, particularly with booster doses, and lower odds of severe outcomes. VE was highest among elderly patients and in those with prior SARS-CoV-2 infection, emphasizing the importance of booster campaigns in vulnerable populations.<\/jats:p>","DOI":"10.1371\/journal.pgph.0006418","type":"journal-article","created":{"date-parts":[[2026,5,12]],"date-time":"2026-05-12T17:24:37Z","timestamp":1778606677000},"page":"e0006418","update-policy":"https:\/\/doi.org\/10.1371\/journal.pgph.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["COVID-19 vaccine effectiveness in preventing severe outcomes and assessing the impact of prior SARS-CoV-2 infection among hospitalized adults in Albania, July 2022-July 2023"],"prefix":"10.1371","volume":"6","author":[{"ORCID":"https:\/\/orcid.org\/0009-0002-8519-968X","authenticated-orcid":true,"given":"Jonilda","family":"Sulo","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8520-3373","authenticated-orcid":true,"given":"Kujtim","family":"Mersini","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Elona","family":"Kureta","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8885-6561","authenticated-orcid":true,"given":"Iris","family":"Hatibi","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Najada","family":"Como","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Esmeralda","family":"Meta","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Migena","family":"Qato","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Eugena","family":"Tomini","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Valbona","family":"Zefi","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Juljana","family":"Nanaj","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Silvia","family":"Bino","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"340","published-online":{"date-parts":[[2026,5,12]]},"reference":[{"key":"pgph.0006418.ref001","author":"World Health Organization","year":"2023"},{"key":"pgph.0006418.ref002","unstructured":"Monthly Public Health Bulletin, Institute of public Health, Tirana Albania. 2023."},{"key":"pgph.0006418.ref003","volume-title":"World Bank Country and Lending Groups","author":"World Bank","year":"2023"},{"key":"pgph.0006418.ref004","doi-asserted-by":"crossref","first-page":"101208","DOI":"10.1016\/j.nmni.2023.101208","article-title":"Trends in SARS-CoV-2 seroprevalence in Albania during the 2021-2022 pandemic year","volume":"56","author":"G Sulcebe","year":"2023","journal-title":"New Microbes New Infect"},{"key":"pgph.0006418.ref005","volume-title":"Interim recommendations for the use of mRNA COVID-19 vaccines: Interim guidance. Technical document","author":"World Health Organization","year":"2023"},{"key":"pgph.0006418.ref006","volume-title":"Annual Public Health Bulletin","year":"2023"},{"issue":"47","key":"pgph.0006418.ref007","first-page":"2300187","article-title":"Vaccine effectiveness against COVID-19 hospitalisation in adults (\u2265\u00a020 years) during Omicron-dominant circulation: I-MOVE-COVID-19 and VEBIS SARI VE networks, Europe, 2021 to 2022","volume":"28","author":"AM Rose","year":"2023","journal-title":"Euro Surveill"},{"issue":"47","key":"pgph.0006418.ref008","first-page":"2300186","article-title":"Vaccine effectiveness against COVID-19 hospitalisation in adults (\u2265\u00a020 years) during Alpha- and Delta-dominant circulation: I-MOVE-COVID-19 and VEBIS SARI VE networks, Europe, 2021","volume":"28","author":"AM Rose","year":"2023","journal-title":"Euro Surveill"},{"key":"pgph.0006418.ref009","author":"World Health Organization (WHO)","year":"2022"},{"issue":"1","key":"pgph.0006418.ref010","article-title":"Effects of Confounding Bias in Coronavirus Disease 2019 (COVID-19) and influenza vaccine effectiveness test-negative designs due to correlated influenza and COVID-19 vaccination behaviors","volume":"75","author":"MK Doll","year":"2022","journal-title":"Clin Infect Dis"},{"key":"pgph.0006418.ref011","author":"World Health Organization (WHO)","year":"2014"},{"key":"pgph.0006418.ref012","author":"European Centre for Disease Prevention and Control (ECDC)"},{"issue":"6","key":"pgph.0006418.ref013","doi-asserted-by":"crossref","first-page":"1014","DOI":"10.1111\/irv.13026","article-title":"COVID-19 vaccine effectiveness against hospitalization due to SARS-CoV-2: a test-negative design study based on Severe Acute Respiratory Infection (SARI) sentinel surveillance in Spain","volume":"16","author":"C Mazagatos","year":"2022","journal-title":"Influenza Other Respir Viruses"},{"issue":"4","key":"pgph.0006418.ref014","doi-asserted-by":"crossref","first-page":"340","DOI":"10.1056\/NEJMoa2115481","article-title":"Duration of protection against mild and severe disease by COVID-19 vaccines","volume":"386","author":"N Andrews","year":"2022","journal-title":"N Engl J Med"},{"issue":"15","key":"pgph.0006418.ref015","doi-asserted-by":"crossref","first-page":"1393","DOI":"10.1056\/NEJMoa2114255","article-title":"Protection of BNT162b2 vaccine booster against COVID-19 in Israel","volume":"385","author":"YM Bar-On","year":"2021","journal-title":"N Engl J Med"},{"issue":"1","key":"pgph.0006418.ref016","doi-asserted-by":"crossref","first-page":"86","DOI":"10.1056\/NEJMc2206576","article-title":"Neutralization escape by SARS-CoV-2 Omicron subvariants BA.2.12.1, BA.4, and BA.5","volume":"387","author":"NP Hachmann","year":"2022","journal-title":"N Engl J Med"},{"issue":"23","key":"pgph.0006418.ref017","doi-asserted-by":"crossref","first-page":"2201","DOI":"10.1056\/NEJMoa2118946","article-title":"Protection and waning of natural and hybrid immunity to SARS-CoV-2","volume":"386","author":"Y Goldberg","year":"2022","journal-title":"N Engl J Med"},{"issue":"5","key":"pgph.0006418.ref018","doi-asserted-by":"crossref","first-page":"556","DOI":"10.1016\/S1473-3099(22)00801-5","article-title":"Protective effectiveness of previous SARS-CoV-2 infection and hybrid immunity against the omicron variant and severe disease: a systematic review and meta-regression","volume":"23","author":"N Bobrovitz","year":"2023","journal-title":"Lancet Infect Dis"},{"issue":"3","key":"pgph.0006418.ref019","first-page":"204","article-title":"Association between mRNA vaccination and COVID-19 hospitalization and disease severity","volume":"327","author":"MW Tenforde","year":"2022","journal-title":"JAMA"},{"issue":"9","key":"pgph.0006418.ref020","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0274008","article-title":"COVID-19 vaccine effectiveness against symptomatic SARS-CoV-2 infections, COVID-19 related hospitalizations and deaths, among individuals aged \u226565 years in Portugal: A cohort study based on data-linkage of national registries February-September 2021","volume":"17","author":"A Machado","year":"2022","journal-title":"PLoS One"},{"issue":"50","key":"pgph.0006418.ref021","first-page":"7373","article-title":"Sustained immunity with booster doses in elderly populations: a Canadian cohort study","volume":"40","author":"DM Skowronski","year":"2022","journal-title":"Vaccine"},{"issue":"7","key":"pgph.0006418.ref022","doi-asserted-by":"crossref","first-page":"639","DOI":"10.1001\/jama.2022.0470","article-title":"Association between 3 doses of mRNA COVID-19 vaccine and symptomatic infection caused by the SARS-CoV-2 Omicron and Delta Variants","volume":"327","author":"EK Accorsi","year":"2022","journal-title":"JAMA"},{"issue":"7","key":"pgph.0006418.ref023","doi-asserted-by":"crossref","first-page":"255","DOI":"10.15585\/mmwr.mm7107e2","article-title":"Waning 2-dose and 3-dose effectiveness of mRNA vaccines against COVID-19-associated emergency department and urgent care encounters and hospitalizations among adults during periods of Delta and Omicron variant predominance \u2014 VISION Network, 10 States, August 2021-January 2022","volume":"71","author":"JM Ferdinands","year":"2022","journal-title":"MMWR Morb Mortal Wkly Rep"}],"container-title":["PLOS Global Public Health"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pgph.0006418","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,5,12]],"date-time":"2026-05-12T17:24:43Z","timestamp":1778606683000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pgph.0006418"}},"subtitle":[],"editor":[{"given":"Abram L.","family":"Wagner","sequence":"first","affiliation":[],"role":[{"role":"editor","vocabulary":"crossref"}]}],"short-title":[],"issued":{"date-parts":[[2026,5,12]]},"references-count":23,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2026,5,12]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pgph.0006418","relation":{},"ISSN":["2767-3375"],"issn-type":[{"value":"2767-3375","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,5,12]]}}}