Epidemiological and clinical characteristics of hospitalized human metapneumovirus patients in Israel, 2015-2021: A retrospective cohort study.

This study evaluated the epidemiological and clinical characteristics of human metapneumovirus (hMPV) infection among hospitalized patients with acute respiratory infections during 2015-2021 and assessed the impact of the coronavirus disease 2019 pandemic on hMPV infection. A single-center, retrospective cohort study was performed, including pediatric and adult patients with laboratory-confirmed hMPV. Of a total of 990 patients, 253 (25.6%), 105 (10.6%), 121 (12.2%), and 511 (51.6%) belonged to age groups 0-2, 3-17, 18-59, and ≥60 years, respectively. The highest percentage (23.0%) of patients were hospitalized during 2019 and the lowest (4.7%) during 2020. Patients < 18 years experienced high rates of comorbidities (immunodeficiencies: 14.4% and malignancies: 29.9%). Here, 37/39 (94.9%) of all bronchiolitis cases were diagnosed in patients < 2 years, whereas more patients in older age groups were diagnosed with pneumonia. A greater proportion of hMPV patients diagnosed with viral coinfection (mostly respiratory syncytial virus and adenovirus) were <18 years. The highest percentages of intensive care unit admissions were recorded among patients < 18 years. Our findings demonstrate that hMPV is an important cause of morbidity in young children and a possibly underestimated cause of morbidity among older adults.

Kinetics of cellular and humoral responses to third BNT162B2 COVID-19 vaccine over six months in heart transplant recipients - implications for the omicron variant.

BACKGROUND: The durability of the immune response following the 3-dose BNT162b2 vaccination is unknown. The complexity of the situation is enhanced by the threat that highly transmissible variants may further accelerate the decline in the protection afforded by mRNA vaccines. METHODS: One hundred and three 3-dose-vaccinated heart transplant recipients were longitudinally assessed for the kinetics of variant-specific neutralization (Cohort 1, n = 60) and SARS-CoV-2-specific-T-cell response (Cohort 2, n = 54) over 6 months. Neutralization and T-cell responses were compared between paired samples at 2 time points, using the Kruskal-Wallis test followed by Dunn's multiple comparison test for continuous variables and McNemar's test for dichotomous variables. The Bonferroni method of p values adjustment for multiple comparison was applied. RESULTS: The third dose induced high neutralization of the wild-type virus and delta variant (geometric mean titer [GMT], 137.2 [95% CI, 84.8-221.9] and 80.6, [95% CI, 49.3-132.0], respectively), and to a lesser degree of the omicron variant (GMT, 10.3 [95% CI, 5.9-17.9]). At 6 months, serum neutralizing activity declined but was still high for the wild-type virus and for the delta variant (GMTs 38.1 [95% CI, 21.2-69.4], p = 0.011; and 28.9 [95% CI, 16.6-52.3], p = 0.022, respectively), but not for the omicron variant (GMT 5.9 [95% CI, 3.4-9.8], p = 0.463). The percentages of neutralizing sera against the wild-type virus, delta and omicron variants increased from 70%, 65%, and 38%, before the third dose, to 93% (p < 0.001), 88% (p < 0.001), and 48% (p = 0.021) at 3 weeks after, respectively; and remained high through the 6 months for the wild-type (80%, p = 0.06) and delta (77%, p = 0.102). The third dose induced the development of a sustained SARS-CoV-2-specific-T-cell population, which persisted through 6 months. CONCLUSIONS: The third BNT162b2 dose elicited a durable SARS-CoV-2-specific T-cell response and induced effective and durable neutralization of the wild-type virus and the delta variant, and to a lesser degree of the omicron variant.