Dataset Information

Half dose ChAdOx1 nCoV-19 vaccine was equivalent to full doses to reduce moderate and severe COVID-19 cases.

ABSTRACT:

Objectives

Previously, we presented the effectiveness of ChAdOx1 nCoV-19 half-dose (HD) immunization for preventing new COVID-19 cases. Here, we evaluated the administration of an HD of ChAdOx1 nCoV-19 in the primary immunization protocol (up to two doses) in reducing moderate and severe cases, hospitalizations, and deaths when compared to the administration of full doses (FD) after a long-term follow-up.

Methods

We evaluated data from 29,469 participants between January 2021 and November 2022 who received an HD or FD vaccine and crossed this information with their medical records to identify those who developed moderate or severe cases. All participants were classified into four groups according to their immunization status and followed 500 days after the last vaccine administration.

Results

The propensity-score matching analysis indicates that the administration of the two HDs of ChAdOx1 nCoV-19 was equivalent to the use of two FDs to reduce moderate and severe COVID-19 cases. The relative risk of being infected and developing moderate or severe conditions after the administration of at least one HD or FD was similar 150 or 500 days after the administration of the immunizers.

Conclusion

Administering two HDs can be used safely as a cost-effective alternative to the primary immunization protocol.

SUBMITTER: Galvao-Lima LJ

PROVIDER: S-EPMC10637913 | biostudies-literature | 2023 Dec

REPOSITORIES: biostudies-literature

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Publications

Half dose ChAdOx1 nCoV-19 vaccine was equivalent to full doses to reduce moderate and severe COVID-19 cases.

Galvão-Lima Leonardo J LJ de Medeiros Júnior Nésio Fernandes NF Jesus Galileu S GS Morais Antônio H F AHF Caldeira-Silva Gleyson J P GJP Queiroz Dos Santos João Paulo JP Rocha Marcella M Marques Dos Santos Marquiony M Freire Pierre A PA Silva Rodrigo D RD Gouvea Maria da Penha Gomes MDPG Neto Lauro Ferreira Pinto LFP Domingues Carla Magda Allan Santos CMAS Teixeira-Carvalho Andréa A Martins-Filho Olindo Assis OA Valim Valéria V Valentim Ricardo A M RAM

IJID regions 20230930

<h4>Objectives</h4>Previously, we presented the effectiveness of ChAdOx1 nCoV-19 half-dose (HD) immunization for preventing new COVID-19 cases. Here, we evaluated the administration of an HD of ChAdOx1 nCoV-19 in the primary immunization protocol (up to two doses) in reducing moderate and severe cases, hospitalizations, and deaths when compared to the administration of full doses (FD) after a long-term follow-up.<h4>Methods</h4>We evaluated data from 29,469 participants between January 2021 and ...[more]

PMID: 37953882

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Project description:Fractional dose is an important strategy to increase access to vaccines. This study evaluated the effectiveness, safety, and immunogenicity of half dose of ChAdOx1 nCoV-19 vaccine. A non-inferiority non-randomized controlled trial compared a half dose of ChAdOx1 nCoV-19 with the full dose, with an interval of 8 to 10 weeks, in individuals aged 18-49 years. The primary endpoints were the incidence rate of new cases/1,000 person-year at 90 days after 14 days of the second dose, confirmed by RT-PCR and new cases registered at SUS National Health Surveillance Database (e-SUS VS). The anti-SARS-CoV-2 spike (S) protein receptor binding domain (RBD) by chemiluminescence and the neutralizing antibodies by plaque reduction neutralization test (PRNT) were titrated. The soluble biomarkers were quantified with a multiplex immunoassay. Follow-up was 90 days after 14 days of the second dose. A total of 29,598 individuals were vaccinated. After exclusion, 16,570 individuals who received half a dose and 6,402 who received full doses were analyzed. The incidence of new cases confirmed by RT-PCR of half dose was non-inferior to full dose (23.7 vs. 25.7 cases per 1,000 persons-year [coefficient group -0.09 CI95%(-0.49 to 0.31)], even after adjusting for age and sex. There were no deaths or hospitalization after immunization of either group. Immunogenicity was evaluated in a subsample (N=558) compared to 154 healthcare workers who received a full dose. The seroconversion rate in seronegative individuals at baseline half dose was 99.8%, similar to that of the full dose (100%). Geometric mean concentration (95% CI; BAU/mL) were half dose = 188 (163-217) and full dose = 529 (423-663) (p < 0.001). In seropositive subjects at baseline (pre-immune individuals), the first dose induced very high and similar IgG-S in half dose 1,359 (1,245-1,483) and full dose 1,354 (1,048-1,749) BAU/mL. A half dose induced a high increase in plasma chemokines, pro-inflammatory/regulatory cytokines, and growth factors. The frequency of adverse events was similar. No serious adverse events or deaths were reported. A half dose of ChAdOx1 nCoV-19 is as effective, safe, and immunogenic as the full dose. The immune response in pre-immune (seropositive in the baseline) individuals indicates that the half dose may be a booster dose schedule.

Project description:The ChAdOx1 nCoV-19 (AZD1222) vaccine is one of the most commonly delivered SARS-CoV-2 vaccines worldwide; however, few clinical studies have investigated its immunogenicity in dialysis patients. We prospectively enrolled 123 patients on maintenance hemodialysis at a medical center in Taiwan. All patients were infection-naive, had received two doses of the AZD1222 vaccine, and were monitored for 7 months. The primary outcomes were anti-SARS-CoV-2 receptor-binding domain (RBD) antibody concentrations before and after each dose and 5 months after the second dose and neutralization capacity against ancestral SARS-CoV-2, delta, and omicron variants. The anti-SARS-CoV-2 RBD antibody titers significantly increased with time following vaccination, with a peak at 1 month after the second dose (median titer, 498.8 U/mL; interquartile range, 162.5 to 1,050 U/mL), and a 4.7-fold decrease at 5 months. At 1 month after the second dose, 84.6, 83.7, and 1.6% of the participants had neutralizing antibodies against the ancestral virus, delta variant, and omicron variant, respectively, measured by a commercial surrogate neutralization assay. The geometric mean 50% pseudovirus neutralization titers for the ancestral virus, delta variant, and omicron variant were 639.1, 264.2, and 24.7, respectively. The anti-RBD antibody titers correlated well with neutralization capacity against the ancestral virus and delta variant. Transferrin saturation and C-reactive protein were associated with neutralization against the ancestral virus and delta variant. Although two doses of the AZD1222 vaccine initially elicited high anti-RBD antibody titers and neutralization against the ancestral virus and delta variant in hemodialysis patients, neutralizing antibodies against omicron variant were rarely detected, and the anti-RBD and neutralization antibodies waned over time. Additional/booster vaccinations are warranted in this population. IMPORTANCE Patients with kidney failure have worse immune response following vaccination compared to general population, but few clinical studies have investigated immunogenicity of ChAdOx1 nCoV-19 (AZD1222) vaccination in hemodialysis patients. Here, we showed two doses of AZD1222 vaccines lead to high seroconversion rate of anti-SARS-CoV-2 receptor-binding domain (RBD) antibodies, and more than 80% patients acquired neutralizing antibodies against ancestral virus and delta variant. However, seldom did they obtain neutralizing antibodies against the omicron variant. The geometric mean 50% pseudovirus neutralization titer against the ancestral virus was 25.9-fold higher than that against the omicron variant. Also, there was a substantial decay in anti-RBD titers with time. Our findings provided evidence supporting that more protective measures, including additional/booster vaccinations, is warranted in these patients during the current COVID-19 pandemic.

Project description:BackgroundSeveral cases of unusual thrombotic events and thrombocytopenia have developed after vaccination with the recombinant adenoviral vector encoding the spike protein antigen of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (ChAdOx1 nCov-19, AstraZeneca). More data were needed on the pathogenesis of this unusual clotting disorder.MethodsWe assessed the clinical and laboratory features of 11 patients in Germany and Austria in whom thrombosis or thrombocytopenia had developed after vaccination with ChAdOx1 nCov-19. We used a standard enzyme-linked immunosorbent assay to detect platelet factor 4 (PF4)-heparin antibodies and a modified (PF4-enhanced) platelet-activation test to detect platelet-activating antibodies under various reaction conditions. Included in this testing were samples from patients who had blood samples referred for investigation of vaccine-associated thrombotic events, with 28 testing positive on a screening PF4-heparin immunoassay.ResultsOf the 11 original patients, 9 were women, with a median age of 36 years (range, 22 to 49). Beginning 5 to 16 days after vaccination, the patients presented with one or more thrombotic events, with the exception of 1 patient, who presented with fatal intracranial hemorrhage. Of the patients with one or more thrombotic events, 9 had cerebral venous thrombosis, 3 had splanchnic-vein thrombosis, 3 had pulmonary embolism, and 4 had other thromboses; of these patients, 6 died. Five patients had disseminated intravascular coagulation. None of the patients had received heparin before symptom onset. All 28 patients who tested positive for antibodies against PF4-heparin tested positive on the platelet-activation assay in the presence of PF4 independent of heparin. Platelet activation was inhibited by high levels of heparin, Fc receptor-blocking monoclonal antibody, and immune globulin (10 mg per milliliter). Additional studies with PF4 or PF4-heparin affinity purified antibodies in 2 patients confirmed PF4-dependent platelet activation.ConclusionsVaccination with ChAdOx1 nCov-19 can result in the rare development of immune thrombotic thrombocytopenia mediated by platelet-activating antibodies against PF4, which clinically mimics autoimmune heparin-induced thrombocytopenia. (Funded by the German Research Foundation.).

Project description:Introduction La nouvelle infection par le SRAS-CoV-2 a récemment été déclarée pandémie par l’Organisation mondiale de la santé (OMS). En réponse à la propagation mondiale du virus, de nombreux vaccins ont été développés, comme le vaccin ChAdOx1 nCoV-19. Bien que ce vaccin ait un bon profil de sécurité, ses effets secondaires ne sont pas encore complètement caractérisés. Nous décrivons onze cas de zona après vaccination. Matériel et méthodes De mars à mai 2021, onze cas de zona après vaccination ont été observés dans notre institution. Résultats Sur les onze patients atteints de zona, 6 étaient des hommes et 5 des femmes. L’âge moyen des patients était de 56,8 ans. À l’exception d’un patient qui avait des antécédents d’hypertension et d’un autre qui était diabétique, aucun n’avait d’antécédents médicaux. L’atteinte thoracique était la plus fréquente, suivie par l’atteinte du trijumeau. Neuf patients ont développé l’éruption après la première dose du vaccin et 2 patients après la deuxième dose. Tous les patients ont reçu du valaciclovir (3 g/jour) pendant dix jours avec un traitement symptomatique. Un seul patient a été hospitalisé et traité par ceftriaxone (2 g/jour) pendant 10 jours en association avec la gentamicine (160 mg/jour) pendant 3 jours. L’évolution était sans complication pour 10 patients, un patient a développé un syndrome régional complexe. Discussion Le zona est particulièrement fréquent au cours des hémopathies malignes, des cancers, des déficits immunitaires, notamment le VIH, et des traitements immunosuppresseurs, l’immunité à médiation cellulaire jouant un rôle important dans la défense antivirale. Des zonas ont également été observés dans plusieurs cas de COVID-19. Ceci pourrait être expliqué par la diminution du nombre absolu de lymphocytes, secondaire à l’infection. Dans la littérature, hormis la réactivation du zona après la vaccination contre la varicelle, il existe très peu de publications associant la vaccination et la survenue du zona. Jusqu’à présent, l’infection par le zona n’a pas été signalée comme étant un effet indésirable de vaccins contre la COVID-19. Il est possible que le zona observé chez nos patients ait été causé par l’immunomodulation induite par le vaccin, car le moment de l’infection a coïncidé avec l’administration du vaccin. Conclusion Notre étude suggère que l’immunomodulation secondaire à l’administration du vaccin contre la COVID-19 peut augmenter le risque de zona. Cependant, ces cas ne prouvent pas la causalité et des études approfondies sont nécessaires pour élucider le lien possible entre la vaccination contre la COVID-19 et la réactivation de l’infection VZV.

Dataset Information

Half dose ChAdOx1 nCoV-19 vaccine was equivalent to full doses to reduce moderate and severe COVID-19 cases.

Objectives

Methods

Results

Conclusion

Publications

Half dose ChAdOx1 nCoV-19 vaccine was equivalent to full doses to reduce moderate and severe COVID-19 cases.

Similar Datasets

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