Boosters protect against SARS-CoV-2 infections in young adults during an Omicron-predominant period

BackgroundWhile booster vaccinations clearly reduce the risk of severe COVID-19 and death, the impact of boosters on SARS-CoV-2 infection has not been fully characterized: doing so requires understanding their impact on asymptomatic and mildly symptomatic infections that often go unreported but nevertheless play an important role in spreading SARS-CoV-2. We sought to estimate the impact of COVID-19 booster doses on SARS-CoV-2 infection in a vaccinated population of young adults during an Omicron BA.1-predominant period. Methods and FindingsWe implemented a cohort study of young adults in a college environment (Cornell Universitys Ithaca campus) from a period when Omicron BA.1 was the predominant SARS-CoV-2 variant on campus (December 5 to December 31, 2021). Participants included 15,800 university students who completed an initial vaccination series with a vaccine approved by the World Health Organization for emergency use, were enrolled in mandatory at-least-weekly surveillance PCR testing, and had no positive SARS-CoV-2 PCR test within 90 days before the start of the study period. Robust multivariable Poisson regression with the main outcome of a positive SARS-CoV-2 PCR test was performed to compare those who completed their initial vaccination series and a booster dose to those without a booster dose. 1,926 unique SARS-CoV-2 infections were identified in the study population. Controlling for sex, student group membership, date of completion of initial vaccination series, initial vaccine type, and temporal effect during the study period, our analysis estimates that receiving a booster dose further reduces the rate of having a PCR-detected SARS-CoV-2 infection relative to an initial vaccination series by 56% (95% confidence interval [42%, 67%], P <0.001). While most individuals had recent booster administration before or during the study period (a limitation of our study), this result is robust to the assumed delay over which a booster dose becomes effective (varied from 1 day to 14 days). The mandatory active surveillance approach used in this study, under which 86% of the person-days in the study occurred, reduces the likelihood of outcome mis-classification. Key limitations of our methodology are that we did not have an a priori protocol or statistical analysis plan because the analysis was initially done for institutional research purposes, and some analysis choices were made after observing the data. ConclusionsWe observed that boosters are effective, relative to completion of initial vaccination series, in further reducing the rate of SARS-CoV-2 infections in a college student population during a period when Omicron BA.1 was predominant; booster vaccinations for this age group may play an important role in reducing incidence of COVID-19.

Seroprevalence of hepatitis E virus in pregnant women in northern Lebanon

Background: Hepatitis E virus is the main cause of acute hepatitis globally. Infection is especially serious in pregnant women in whom the death rate can reach 25%. The prevalence of hepatitis E virus in pregnant women in Lebanon is not known.Aims: This study aimed to investigate the seroprevalence of hepatitis E virus infection in a sample of pregnant women in northern Lebanon.Methods: A total of 450 pregnant women from Tripoli, North Lebanon were enrolled in the study. Sera were tested for the presence of anti-hepatitis E virus IgG antibodies using an ELISA technique. Information was collected on the sociodemo-graphic characteristics of the women and their risk factors for hepatitis E virus infection (drinking-water source, blood transfusion and contact with animals).Results: Only one woman was positive for hepatitis E virus giving a prevalence of 0.22%. She had good living conditions, socioeconomic status and educational level and reported no exposure to any risk factors associated with hepatitis E virus infection. Most of the women (87.3%) had a medium or high income level, 47.1% had a university education and 64.9% drank bottled water. Only a small proportion were exposed to risk factors for hepatitis E virus infection: 14.7% had direct contact with animals and 3.8% had had a blood transfusion.Conclusion: The prevalence of hepatitis E virus infection in the sample was low (0.22%). However, further epidemiological studies among other population groups are required to determine the national prevalence of hepatitis E virus in Lebanon.

Contexte : Le virus de l’hépatite E constitue la principale cause d’hépatite aiguë dans le monde. L’infection est particulièrement grave pour les femmes enceintes, chez qui le taux de mortalité peut atteindre 25 %. La prévalence du virus de l’hépatite E chez les femmes enceintes au Liban n’est pas connue. Objectifs : La présente étude visait à étudier la séroprévalence de l’infection par le virus de l’hépatite E dans un échantillon de femmes enceintes au nord du Liban. Méthodes : Au total, 450 femmes enceintes de Tripoli, dans le nord du Liban, ont été incluses dans l’étude. Des prélèvements sériques ont été effectués à la recherche d’anticorps de la classe des IgG dirigés contre le virus de l’hépatite E en recourant à la méthode ELISA. Des informations ont été recueillies sur les caractéristiques sociodémographiques de ces femmes et leurs facteurs de risque d’infection par le virus de l’hépatite E (source d’eau de boisson, transfusion sanguine et contact avec les animaux). Résultats : Une seule femme a été testée positive au virus de l’hépatite E, pour une prévalence de 0,22 %. Ses conditions de vie, son statut socio-économique et son niveau d’études étaient bons, et elle n’avait indiqué aucune exposition à aucun facteur de risque associé à l’infection par le virus de l’hépatite E. La plupart des femmes (87,3 %) avaient un niveau de revenu moyen à élevé, 47,1 % d’entre elles avaient reçues une formation universitaire et 64,9 % buvaient de l’eau en bouteille. Seule une faible proportion d’entre elles étaient exposées à des facteurs de risque d’infection par le virus de l’hépatite E : 14,7 % d’entre elles avaient un contact direct avec des animaux et 3,8 % avaient reçu une transfusion sanguine. Conclusion : La prévalence de l’infection par le virus de l’hépatite E dans l’échantillon était faible (0,22 %). Cependant, d’autres études épidémiologiques au sein d’autres groupes de population sont nécessaires pour déterminer la prévalence du virus de l’hépatite E à l’échelle nationale au Liban.