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Nadja A Vielot, Yaoska Reyes, Bryan Blette, Fredman González, Christian Toval-Ruiz, Lester Gutiérrez, Samuel Vilchez, Marta Diez-Valcarce, Jan Vinjé, Sylvia Becker-Dreps, Filemón Bucardo


Background: Norovirus and sapovirus cause a large burden of acute gastroenteritis (AGE) in young children. We assessed protection conferred by norovirus and sapovirus AGE episodes against future episodes. Methods: Between June 2017 and July 2018, we recruited 444 newborns in León, Nicaragua. Weekly household surveys identified AGE episodes over 36 months, and AGE stools were tested by reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) for norovirus genogroup (G)I/GII and sapovirus. We used recurrent-event Cox models and negative control methods to estimate protection conferred by first episodes, controlling for observed and unobserved risk factors, respectively. Results: Sapovirus episodes conferred a 69% reduced hazard of subsequent episodes using the negative control method. Norovirus GI (hazard ratio [HR] = 0.67; 95% confidence interval [CI] = 0.31, 1.3) and GII (HR = 0.20; 95% CI = 0.04, 0.44) episodes also appeared highly protective. Protection against norovirus GII was enhanced following two episodes. Conclusions: Evidence of natural immunity in early childhood provides optimism for the future success of pediatric norovirus and sapovirus vaccines.


Vielot NA, Reyes Y, Blette B, González F, Toval-Ruiz C, Gutiérrez L, Vilchez S, Diez-Valcarce M, Vinjé J, Becker-Dreps S, Bucardo F. First Episodes of Norovirus and Sapovirus Gastroenteritis Protect Against Subsequent Episodes in a Nicaraguan Birth Cohort. Epidemiology. 2022 Sep 1;33(5):650-653. doi: 10.1097/EDE.0000000000001500. Epub 2022 Jun 10. PMID: 35700200; PMCID: PMC9378628.

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