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Intranasal ChAdOx1 nCoV-19/AZD1222 vaccination reduces shedding of SARS-CoV-2 D614G in rhesus macaques.

ABSTRACT: Intramuscular vaccination with ChAdOx1 nCoV-19/AZD1222 protected rhesus macaques against pneumonia but did not reduce shedding of SARS-CoV-2. Here we investigate whether intranasally administered ChAdOx1 nCoV-19 reduces shedding, using a SARS-CoV-2 virus with the D614G mutation in the spike protein. Viral load in swabs obtained from intranasally vaccinated hamsters was significantly decreased compared to controls and no viral RNA or infectious virus was found in lung tissue, both in a direct challenge and a transmission model. Intranasal vaccination of rhesus macaques resulted in reduced shedding and a reduction in viral load in bronchoalveolar lavage and lower respiratory tract tissue. In conclusion, intranasal vaccination reduced shedding in two different SARS-CoV-2 animal models, justifying further investigation as a potential vaccination route for COVID-19 vaccines.

SUBMITTER: van Doremalen N

PROVIDER: S-EPMC7808328 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundPost-marketing surveillance for COVID-19 vaccines during the pandemic identified an extremely rare thrombosis with thrombocytopenia syndrome (TTS) reported post-vaccination, requiring further characterisation to improve diagnosis and management.MethodsWe searched the AstraZeneca Global Safety Database (through April 26, 2021) for cases with co-reported thrombocytopenia and thrombosis (using standardised MedDRA queries/high-level terms) following AZD1222 (ChAdOx1 nCoV-19). Cases were adjudicated by experts as 'typical','possible', 'no' or 'unknown' according to available TTS criteria. Additional confirmatory datasets (May 20-June 20, October 1-December 28) were evaluated.FindingsWe identified 573 reports, including 273 (47.6 %) 'typical' and 171 (29.8 %) 'possible' TTS cases. Of these 444 cases, 275 (61.9 %) were female, median age was 50.0 years (IQR: 38.0-60.0). Cerebral venous sinus thrombosis was reported in 196 (44.1 %) cases, splanchnic venous thrombosis in 65 (14.6 %) and thromboses at multiple sites in 119 (26.8 %). Median time to onset was 12.0 days (IQR: 9.0-15.0). Comparison with a pre-pandemic reference population indicated higher rates of autoimmune disorders (13.8 %, 4.4 %), previous heparin therapy (7.4 %, 1.2 %), history of thrombosis (5.5 %, 1.4 %), and immune thrombocytopenia (6.1 %, 0.2 %). Fatality rate was 22.2 % (127/573) overall and 23.6 % (105/444) in 'typical'/'possible' TTS, which decreased from 39.0 % (60/154) in February/March to 15.5 % (45/290) in April. Overall patterns were similar in confirmatory datasets.ConclusionsThe reporting rate of 'typical'/'possible' TTS post first-dose vaccination in this dataset is 7.5 per million vaccinated persons; few cases were reported after subsequent doses, including booster doses. Peak reporting coincided with media-driven attention. Medical history differences versus a reference population indicate potentially unidentified risk factors. The decreasing fatality rate correlates with increasing awareness and publication of diagnostic/treatment guidelines. Adjudication was hindered by unreported parameters, and an algorithm was developed to classify potential TTS cases; comprehensive reporting could help further improve definition and management of this extremely rare syndrome.

Project description:BackgroundThe safety and efficacy of the AZD1222 (ChAdOx1 nCoV-19) vaccine in a large, diverse population at increased risk for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the United States, Chile, and Peru has not been known.MethodsIn this ongoing, double-blind, randomized, placebo-controlled, phase 3 clinical trial, we investigated the safety, vaccine efficacy, and immunogenicity of two doses of AZD1222 as compared with placebo in preventing the onset of symptomatic and severe coronavirus disease 2019 (Covid-19) 15 days or more after the second dose in adults, including older adults, in the United States, Chile, and Peru.ResultsA total of 32,451 participants underwent randomization, in a 2:1 ratio, to receive AZD1222 (21,635 participants) or placebo (10,816 participants). AZD1222 was safe, with low incidences of serious and medically attended adverse events and adverse events of special interest; the incidences were similar to those observed in the placebo group. Solicited local and systemic reactions were generally mild or moderate in both groups. Overall estimated vaccine efficacy was 74.0% (95% confidence interval [CI], 65.3 to 80.5; P<0.001) and estimated vaccine efficacy was 83.5% (95% CI, 54.2 to 94.1) in participants 65 years of age or older. High vaccine efficacy was consistent across a range of demographic subgroups. In the fully vaccinated analysis subgroup, no severe or critical symptomatic Covid-19 cases were observed among the 17,662 participants in the AZD1222 group; 8 cases were noted among the 8550 participants in the placebo group (<0.1%). The estimated vaccine efficacy for preventing SARS-CoV-2 infection (nucleocapsid antibody seroconversion) was 64.3% (95% CI, 56.1 to 71.0; P<0.001). SARS-CoV-2 spike protein binding and neutralizing antibodies increased after the first dose and increased further when measured 28 days after the second dose.ConclusionsAZD1222 was safe and efficacious in preventing symptomatic and severe Covid-19 across diverse populations that included older adults. (Funded by AstraZeneca and others; ClinicalTrials.gov number, NCT04516746.).

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Intranasal ChAdOx1 nCoV-19/AZD1222 vaccination reduces shedding of SARS-CoV-2 D614G in rhesus macaques.

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