Ranzani, OtavioHitchings, Matt D.T.Melo, Rosana Leite deFrança, Giovanny V.A. deFernandes, Cássia de Fátima R.Lind, Margaret L.Torres, Mario Sergio ScaramuzziniTsuha, Daniel EnriqueDavid, Leticia C.S.Said, Rodrigo F.C.Almiron, MariaOliveira, Roberto D. deCummings, Derek A.T.Dean, Natalie E.Andrews, Jason R.Ko, Albert I.Croda, Julio2022-12-142022-12-142022Ranzani OT, Hitchings MDT, de Melo RL, de França GVA, Fernandes CFR, Lind ML, Torres MSS, Tsuha DH, David LCS, Said RFC, Almiron M, de Oliveira RD, Cummings DAT, Dean NE, Andrews JR, Ko AI, Croda J. Effectiveness of an inactivated Covid-19 vaccine with homologous and heterologous boosters against Omicron in Brazil. Nat Commun. 2022 Oct 6;13(1):5536. DOI: 10.1038/s41467-022-33169-02041-1723http://hdl.handle.net/10230/55135The effectiveness of inactivated vaccines (VE) against symptomatic and severe COVID-19 caused by omicron is unknown. We conducted a nationwide, test-negative, case-control study to estimate VE for homologous and heterologous (BNT162b2) booster doses in adults who received two doses of CoronaVac in Brazil in the Omicron context. Analyzing 1,386,544 matched-pairs, VE against symptomatic disease was 8.6% (95% CI, 5.6-11.5) and 56.8% (95% CI, 56.3-57.3) in the period 8-59 days after receiving a homologous and heterologous booster, respectively. During the same interval, VE against severe Covid-19 was 73.6% (95% CI, 63.9-80.7) and 86.0% (95% CI, 84.5-87.4) after receiving a homologous and heterologous booster, respectively. Waning against severe Covid-19 after 120 days was only observed after a homologous booster. Heterologous booster might be preferable to individuals with completed primary series inactivated vaccine.application/pdfeng© The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.info:eu-repo/semantics/articlehttp://dx.doi.org/10.1038/s41467-022-33169-0EpidemiologySARS-CoV-2Vaccinesinfo:eu-repo/semantics/openAccess