Heterologous versus homologous COVID-19 booster vaccination in previous recipients of two doses of CoronaVac COVID-19 vaccine in Brazil (RHH-001): a phase 4, non-inferiority, single blind, randomised study.

INTRODUCTION: The inactivated whole-virion SARS-CoV-2 vaccine (CoronaVac, Sinovac) has been widely used in a two-dose schedule. We assessed whether a third dose of the homologous or a different vaccine could boost immune responses. METHODS: RHH-001 is a phase 4, participant masked, two centre, safety and immunogenicity study of Brazilian adults (18 years and older) in São Paulo or Salvador who had received two doses of CoronaVac 6 months previously. The third heterologous dose was of either a recombinant adenoviral vectored vaccine (Ad26.COV2-S, Janssen), an mRNA vaccine (BNT162b2, Pfizer-BioNTech), or a recombinant adenoviral-vectored ChAdOx1 nCoV-19 vaccine (AZD1222, AstraZeneca), compared with a third homologous dose of CoronaVac. Participants were randomly assigned (5:6:5:5) by a RedCAP computer randomisation system stratified by site, age group (18-60 years or 61 years and over), and day of randomisation, with a block size of 42. The primary outcome was non-inferiority of anti-spike IgG antibodies 28 days after the booster dose in the heterologous boost groups compared with homologous regimen, using a non-inferiority margin for the geometric mean ratio (heterologous vs homologous) of 0·67. Secondary outcomes included neutralising antibody titres at day 28, local and systemic reactogenicity profiles, adverse events, and serious adverse events. This study was registered with Registro Brasileiro de Ensaios Clínicos, number RBR-9nn3scw. FINDINGS: Between Aug 16, and Sept 1, 2021, 1240 participants were randomly assigned to one of the four groups, of whom 1239 were vaccinated and 1205 were eligible for inclusion in the primary analysis. Antibody concentrations were low before administration of a booster dose with detectable neutralising antibodies of 20·4% (95% CI 12·8-30·1) in adults aged 18-60 years and 8·9% (4·2-16·2) in adults 61 years or older. From baseline to day 28 after the booster vaccine, all groups had a substantial rise in IgG antibody concentrations: the geometric fold-rise was 77 (95% CI 67-88) for Ad26.COV2-S, 152 (134-173) for BNT162b2, 90 (77-104) for ChAdOx1 nCoV-19, and 12 (11-14) for CoronaVac. All heterologous regimens had anti-spike IgG responses at day 28 that were superior to homologous booster responses: geometric mean ratios (heterologous vs homologous) were 6·7 (95% CI 5·8-7·7) for Ad26.COV2-S, 13·4 (11·6-15·3) for BNT162b2, and 7·0 (6·1-8·1) for ChAdOx1 nCoV-19. All heterologous boost regimens induced high concentrations of pseudovirus neutralising antibodies. At day 28, all groups except for the homologous boost in the older adults reached 100% seropositivity: geometric mean ratios (heterologous vs homologous) were 8·7 (95% CI 5·9-12·9) for Ad26.COV2-S vaccine, 21·5 (14·5-31·9) for BNT162b2, and 10·6 (7·2-15·6) for ChAdOx1 nCoV-19. Live virus neutralising antibodies were also boosted against delta (B.1.617.2) and omicron variants (B.1.1.529). There were five serious adverse events. Three of which were considered possibly related to the vaccine received: one in the BNT162b2 group and two in the Ad26.COV2-S group. All participants recovered and were discharged home. INTERPRETATION: Antibody concentrations were low at 6 months after previous immunisation with two doses of CoronaVac. However, all four vaccines administered as a third dose induced a significant increase in binding and neutralising antibodies, which could improve protection against infection. Heterologous boosting resulted in more robust immune responses than homologous boosting and might enhance protection. FUNDING: Ministry of Health, Brazil.

Primary Immunodeficiency May Be Misdiagnosed as Cow's Milk Allergy: Seven Cases Referred to a Tertiary Pediatric Hospital.

Introduction. The presence of eczema and gastrointestinal manifestations are often observed in cow's milk allergy (CMA) and also in some primary immunodeficiency diseases (PID). Objective. To describe 7 patients referred to a tertiary allergy/immunology Center with a proposed diagnosis of CMA, who were ultimately diagnosed with PID. Methods. This was a retrospective study based on clinical and laboratory data from medical records. Results. Seven patients (6 males) aged between 3 mo and 6 y were referred to our clinic with a proposed diagnosis of CMA. They presented with eczema and/or gastrointestinal symptoms. Five were receiving replacement formula. All patients presented with other clinical features, including severe/recurrent infections unrelated to CMA, and two of them had a positive family history of PID. Laboratory tests showed immune system dysfunctions in all patients. Hyper-IgE and Wiskott-Aldrich syndromes, CD40L deficiency, severe combined immunodeficiency, X-linked agammaglobulinemia, transient hypogammaglobulinemia of infancy, and chronic granulomatous disease were diagnosed in these children. In conclusion, allergic diseases and immunodeficiency are a result of a different spectrum of abnormalities in the immune system and may be misdiagnosed. Educational programs on PID among clinical physicians and pediatricians can reduce the occurrence of this misdiagnosis.

Impacto do tratamento com imunoglobulina humana intravenosa no número de pneumonias em pacientes com deficiência de anticorpo / Efficacy of immunoglobulin therapy in reducing pneumonia

A imunodeficiência comum variável (ICV) e a agamaglobulinemia ligada ao X (ALX) são imunodeficiências primárias caracterizadas por deficiência de anticorpos e susceptibilidade aumentada a infecções, sendo a pneumonia a infecção mais frequente. Esses pacientes são tratados com infusões regulares de imunoglobulina intravenosa (IGIV). Objetivo: Avaliar a frequência de pneumonias e o impacto do tratamento com IGIV em 25 pacientes com ICV ou ALX. Métodos: Análise retrospectiva dos prontuários médicos de pacientes com diagnóstico confirmado de ICV ou ALX, em tratamento regular com IGIV. Resultados: Analisamos 25 pacientes (18 com ICV e 7 com ALX; 14 homens e 11 mulheres; média de idade atual de 18 anos). A média de idade ao início dos sintomas foi de 5,7 anos e a média de idade ao diagnóstico foi de 11,5 anos. Treze pacientes (52%) apresentaram pneumonia como primeira manifestação da imunodeficiência. A pneumonia foi a infecção mais frequente nesses pacientes antes do diagnóstico – 22 pacientes (88%) tiveram pelo menos um episódio de pneumonia antes do diagnóstico e, desses, 59% tiveram mais do que 5 episódios – antes do diagnóstico houve uma média de 6,2 episódios de pneumonia por paciente. Após início do tratamento com IGIV, 10 pacientes (40%) tiveram algum episódio de pneumonia, com uma média de 1,5 episódio por paciente. Nove pacientes (36%) apresentavam algum tipo de sequela pulmonar antes do diagnóstico da imunodeficiência. Conclusão: O tratamento com IGIV é eficaz na redução dos episódios de pneumonia nesses pacientes. O diagnóstico e tratamento precoces são de extrema importância.

Common variable immunodeficiency (CVID) and X-linked agammaglobulinemia (XLA) are primary immune disorders characterized by antibody deficiency and increased susceptibility to infections, especially pneumonia. Replacement therapy with intravenous immunoglobulin (IVIG) is the standard treatment. Objective: To assess the frequency of pneumonia in 25 patients with CVID or XLA and the effectiveness of intravenous immunoglobulin replacement therapy in these patients. Methods: a descriptive study, based on a retrospective analysis of medical records from 25 patients with diagnosis of CVID or XLA treated with IVIG. Results: A total of 25 patients were studied (18 with CVID and 7 with XLA; 14 male and 11 female; mean current age, 18 years). The mean age of onset of symptoms was 5.7 years and the mean age of diagnosis was 11.5 years. Pneumonia was the most common primary clinical presentation (13 patients – 52%). Twenty-two (88%) of the 25 patients had pneumonia at least once before diagnosis and 13 out of 22 of these patients had more than 5 episodes. Pre-diagnosis patients had an average of 6.2 episodes of pneumonia. After treatment with IVIG, ten patients (40%) had pneumonia – with an average of 1.5 episode of pneumonia per patient. Conclusion: IVIG treatment provides a remarkable reduction in pneumonia in these patients. Early diagnosis and treatment is mandatory for a positive prognosis.