Immunogenicity of COVID-19 adsorbed inactivated vaccine (CoronaVac) and additional doses of mRNA BNT162b2 vaccine in immunocompromised adults compared with immunocompetent persons.

Inactivated COVID-19 vaccines data in immunocompromised individuals are scarce. This trial assessed the immunogenicity of two CoronaVac doses and additional BNT162b2 mRNA vaccine doses in immunocompromised (IC) and immunocompetent (H) individuals. Adults with solid organ transplant (SOT), hematopoietic stem cell transplant, cancer, inborn immunity errors or rheumatic diseases were included in the IC group. Immunocompetent adults were used as control group for comparison. Participants received two CoronaVac doses within a 28-day interval. IC received two additional BNT162b2 doses and H received a third BNT162b2 dose (booster). Blood samples were collected at baseline, 28 days after each dose, pre-booster and at the trial end. We used three serological tests to detect antibodies to SARS-CoV-2 nucleocapsid (N), trimeric spike (S), and receptor binding domain (RBD). Outcomes included seroconversion rates (SCR), geometric mean titers (GMT) and GMT ratio (GMTR). A total of 241 IC and 100 H adults participated in the study. After two CoronaVac doses, IC had lower SCR than H: anti-N, 33.3% vs 79%; anti-S, 33.8% vs 86%, and anti-RBD, 48.5% vs 85%, respectively. IC also showed lower GMT than H: anti-N, 2.3 vs 15.1; anti-S, 58.8 vs 213.2 BAU/mL; and anti-RBD, 22.4 vs 168.0 U/mL, respectively. After the 3rd and 4th BNT162b2 doses, IC had significant anti-S and anti-RBD seroconversion, but still lower than H after the 3rd dose. After boosting, GMT increased in IC, but remained lower than in the H group. CoronaVac two-dose schedule immunogenicity was lower in IC than in H. BNT162b2 heterologous booster enhanced immune response in both groups.

Vaccination in children with immune-mediated disorders

Abstract Objective: To present an updated review of recommendations for the vaccination of children with immune-mediated diseases, with an emphasis on rheumatic and inflammatory diseases. Source of data: Studies published in the PubMed and Scielo databases between 2002 and 2022, Guidelines of Brazilian Scientific Societies, Manuals and Technical Notes of the Ministry of Health of Brazil, on current immunization schedules for special populations. Data synthesis: Immunosuppressive drugs and biological agents reduce the immunogenicity of vaccines and favor susceptibility to infections. The safety and efficacy of immunogens are important points for vaccination in children with immune-mediated diseases. The safety threshold of a vaccine applied to immunocompromised individuals can be reduced when compared to healthy individuals. Very often, the recommendations for the immunization of children with immunemediated diseases follow the recommendations for immunocompromised patients. Vaccination against COVID-19, on the other hand, should ideally occur when the disease is stabilized and in the absence of a low degree of immunosuppression. The patients should be informed about the possibility that the immunization may fail during treatment with immunosuppressants. Specific vaccination schedules should be considered to ensure better protection. Conclusions: Recent studies have allowed updating the recommendations on the safety and immunogenicity of vaccination in children with immune-mediated diseases, especially for live attenuated vaccines. There is a scarcity of data on the safety and efficacy of COVID-19 vaccines in patients, particularly pediatric patients, with rheumatic diseases. The completion of ongoing studies is expected to help guide recommendations on COVID-19 vaccines in this group of patients.

Reações de hipersensibilidade a vacinas / Hypersensitivity reactions to vaccines

O desenvolvimento e a ampliação do uso das vacinas durante décadas contribuíram para o controle e erradicação de doenças infecciosas, causando um grande impacto na saúde pública no mundo. A análise de segurança das vacinas percorre criteriosos processos e fases dos estudos clínicos, um dos pilares essenciais para aprovação regulatória e utilização do produto na população. O evento supostamente atribuído à vacinação e imunização (ESAVI), terminologia atual, é definido como qualquer ocorrência médica indesejada após a vacinação que possui, ou não, uma relação causal com o uso de uma vacina ou outro imunobiológico. Cabe ressaltar que eventos adversos mais raros ou inesperados, incluindo os eventos de hipersensibilidade, poderão ocorrer na fase pós-comercialização, quando as vacinas são aplicadas em milhões de pessoas. Neste artigo, serão discutidos os principais aspectos relacionados aos eventos adversos de hipersensibilidade pós-vacinais de interesse do especialista, e os desafios frente ao reconhecimento do agente causal e conduta a ser adotada. Além disso, serão revisados os potenciais alérgenos presentes nas vacinas de uso rotineiro para auxiliar o profissional de saúde na identificação de pacientes com potencial de risco de ESAVI por tais componentes. A atualização do conhecimento acerca da segurança e dos benefícios das vacinas pelos profissionais de saúde, sobretudo em populações especiais, contribui para condutas em imunização mais apropriadas, reduzindo o risco de exposição a um possível alérgeno em pessoas comprovadamente alérgicas às vacinas ou a alguns dos seus componentes, além de evitar contraindicações desnecessárias em eventos coincidentes ou não graves.

The expansion of vaccine use and development in recent decades has contributed to the control and eradication of infectious diseases, causing a major impact on public health worldwide. Vaccine safety analysis, which involves careful processes and clinical study, is one of the essential pillars of regulatory approval and use in the population. In current terminology, events supposedly attributable to vaccination and immunization (ESAVI) are defined as any unwanted medical occurrence after vaccination that may or may not have a causal relationship with vaccines or other immunobiologicals. It is noteworthy that rare or unexpected adverse events, including hypersensitivity, can occur during the post-marketing phase, when vaccines are administered to millions of people. In this article, we will discuss the main aspects of post-vaccine hypersensitivity events of interest to specialists and challenges to recognizing the causal agent and appropriate clinical practice. Potential allergens in routine vaccines will also be reviewed to help health professionals identify patients with a potential risk of ESAVI due to such components. Updating health professionals' knowledge about the safety and benefits of vaccines, particularly in special populations, can contribute to more appropriate clinical practice regarding immunization, reducing the risk of exposure to possible allergens in people with allergies to vaccines or their components, avoiding unnecessary contraindications in coincidental or non-serious events.

Vaccination in children with immune-mediated disorders.

OBJECTIVE: To present an updated review of recommendations for the vaccination of children with immune-mediated diseases, with an emphasis on rheumatic and inflammatory diseases. SOURCE OF DATA: Studies published in the PubMed and Scielo databases between 2002 and 2022, Guidelines of Brazilian Scientific Societies, Manuals and Technical Notes of the Ministry of Health of Brazil, on current immunization schedules for special populations. DATA SYNTHESIS: Immunosuppressive drugs and biological agents reduce the immunogenicity of vaccines and favor susceptibility to infections. The safety and efficacy of immunogens are important points for vaccination in children with immune-mediated diseases. The safety threshold of a vaccine applied to immunocompromised individuals can be reduced when compared to healthy individuals. Very often, the recommendations for the immunization of children with immune-mediated diseases follow the recommendations for immunocompromised patients. Vaccination against COVID-19, on the other hand, should ideally occur when the disease is stabilized and in the absence of a low degree of immunosuppression. The patients should be informed about the possibility that the immunization may fail during treatment with immunosuppressants. Specific vaccination schedules should be considered to ensure better protection. CONCLUSIONS: Recent studies have allowed updating the recommendations on the safety and immunogenicity of vaccination in children with immune-mediated diseases, especially for live attenuated vaccines. There is a scarcity of data on the safety and efficacy of COVID-19 vaccines in patients, particularly pediatric patients, with rheumatic diseases. The completion of ongoing studies is expected to help guide recommendations on COVID-19 vaccines in this group of patients.

Eventos adversos imediatos à vacina febre amarela em crianças alérgicas ao ovo / Immediate adverse events to the yellow fever vaccine in egg-allergic children

Introdução: A vacina contra a febre amarela é cultivada em ovos embrionados de galinha e por isso pode estar contraindicada em indivíduos alérgicos ao ovo. Quando indicada, deve ser aplicada com cautela, após atendimento especializado para avaliação de testes e necessidade de dessensibilização. Sua segurança nos alérgicos ao ovo ainda é pouco estudada. Objetivo: Descrever uma população pediátrica encaminhada por alergia ao ovo, com ou sem diagnóstico comprovado, e os casos de eventos adversos do tipo imediata à vacina contra a febre amarela em um centro de referência para imunobiológicos especiais (CRIE). Material e métodos: Estudo transversal realizado com coleta de dados retrospectivos de crianças entre 9 meses e 12 anos de idade, vacinadas contra a febre amarela com história de alergia ao ovo, no período de 2018 a 2019. Resultados: Dentre as 829 crianças, com diagnóstico presumido de alergia ao ovo, foi identificada uma maior prevalência de sintomáticos após exposição ao ovo, com IgE específica detectável para ovo, clara de ovo e/ou ovoalbumina. Testes para vacina febre amarela foram realizados em 25 crianças com suspeita de alergia grave ou anafilaxia ao ovo, sendo 15 (60%) positivos com a vacina aplicada após dessensibilização. Foram evidenciados apenas 11 (1,3%) casos de evento adverso imediato à vacina, todos classificados como evento adverso não grave e com acometimento especial da pele (reação local e exantema ou urticária). A maioria dos eventos ocorreu em menores de 2 anos, nos sintomáticos após ingesta de ovo e naqueles com altos valores de IgE específica para clara de ovo. Conclusão: Este estudo evidencia que a vacina contra a febre amarela pode ser aplicada em crianças alérgicas ao ovo, de forma segura, inclusive naquelas com história de anafilaxia, desde que em ambiente adequado e com profissionais especializados.

Introduction: The yellow fever vaccine is grown in embryonated chicken eggs and may be contraindicated for egg-allergic individuals. When indicated, it should be applied with caution, after testing and desensitization. Its safety in egg-allergic patients is still poorly studied. Objective: To describe a pediatric population referred for egg allergy, with or without a confirmed diagnosis, and cases of immediate-type adverse events to the yellow fever vaccine at a reference center for special immunobiologicals. Material and methods: This cross-sectional study collected retrospective data from children between 9 months and 12 years of age who were vaccinated for yellow fever between 2018 and 2019 and had a history of egg allergy. Results: In the 829 children diagnosed with presumed egg allergy, a higher prevalence of symptoms was identified after egg exposure, with detectable specific IgE for egg, egg white, and/ or egg albumin. Yellow fever vaccine tests were performed in 25 children suspected of severe allergy or anaphylaxis to eggs, and 15 (60%) tested positive to the vaccine after desensitization. Only 11 (1.3%) cases of immediate adverse events to the vaccine occurred, all classified as non-serious events that especially involved the skin (local reaction and rash or urticaria). Most events occurred in children under 2 years of age, those symptomatic after egg ingestion, and those with high levels of specific IgE to egg white. Conclusion: This study demonstrated that the yellow fever vaccine can be safely administered to egg-allergic children, including those with a history of anaphylaxis, in an appropriate environment and with specialized professionals.

Liver disease accompanied by enteropathy in common variable immunodeficiency: Common pathophysiological mechanisms.

Common variable immunodeficiency (CVID) is one of the inborn errors of immunity that have the greatest clinical impact. Rates of morbidity and mortality are higher in patients with CVID who develop liver disease than in those who do not. The main liver disorder in CVID is nodular regenerative hyperplasia (NRH), the cause of which remains unclear and for which there is as yet no treatment. The etiology of liver disease in CVID is determined by analyzing the liver injury and the associated conditions. The objective of this study was to compare CVID patients with and without liver-spleen axis abnormalities in terms of clinical characteristics, as well as to analyze liver and duodenal biopsies from those with portal hypertension (PH), to elucidate the pathophysiology of liver injury. Patients were divided into three groups: Those with liver disease/PH, those with isolated splenomegaly, and those without liver-spleen axis abnormalities. Clinical and biochemical data were collected. Among 141 CVID patients, 46 (32.6%) had liver disease/PH; 27 (19.1%) had isolated splenomegaly; and 68 (48.2%) had no liver-spleen axis abnormalities. Among the liver disease/PH group, patients, even those with mild or no biochemical changes, had clinical manifestations of PH, mainly splenomegaly, thrombocytopenia, and esophageal varices. Duodenal celiac pattern was found to correlate with PH (p < 0.001). We identified NRH in the livers of all patients with PH (n = 11). Lymphocytic infiltration into the duodenal mucosa also correlated with PH. Electron microscopy of liver biopsy specimens showed varying degrees of lymphocytic infiltration and hepatocyte degeneration, which is a probable mechanism of lymphocyte-mediated cytotoxicity against hepatocytes and enterocytes. In comparison with the CVID patients without PH, those with PH were more likely to have lymphadenopathy (p < 0.001), elevated ß2-microglobulin (p < 0.001), low B-lymphocyte counts (p < 0.05), and low natural killer-lymphocyte counts (p < 0.05). In CVID patients, liver disease/PH is common and regular imaging follow-up is necessary. These patients have a distinct immunological phenotype that may predispose to liver and duodenal injury from lymphocyte-mediated cytotoxicity. Further studies could elucidate the cause of this immune-mediated mechanism and its treatment options.

Worsening of asthma control after COVID-19.

Background: SARS-CoV-2 enters lung cells via angiotensin-converting enzyme 2 (ACE2) receptor. Several studies suggest that interleukin-13, an important cytokine involved in T2 inflammation, reduces ACE2 expression, and therefore, asthma would not be a significant risk factor for the development of severe COVID-19. However, several asthma-related risk factors should be valued during the concurrent occurrence of asthma and COVID-19. The purpose of this study was to compare the evolution of asthma in patients who had COVID-19 with those who did not have the disease. Methods: This was an observational and retrospective study involving asthmatic patients followed up at a tertiary center. Patients were assessed for severity of asthma, atopy, comorbidities, and COVID-19. Worsening of asthma was considered when, during the period of Sept 2020 to Oct 2021, patients referred an increasing of asthma symptoms and a need to increment their maintenance therapy. Results: This study included 208 asthmatic patients, the mean age was 52.75 years, 79.81% were atopic asthmatics, and 59 (28.37%) had laboratory-confirmed coronavirus disease. Of all patients infected with the SARS-CoV-2, eleven (18.64%) needed hospitalization and required oxygen supply with an O2 mask. Comparing the worsening of asthma between patients who had COVID-19 and those who had not the disease, there was a statistically significant difference, 33.90 vs. 11.41%, respectively (p < 0.001). There was no statistical significance regarding asthma comorbidities. Conclusion: This study assessed a group of asthmatic patients that had COVID-19, and that although the respiratory symptoms related to COVID-19 were mild to moderate, a subgroup of these asthmatic patients evolved with a chronic worsening of their asthma requiring an increment in asthma medication to control the disease.

COVID-19 and isolation: Risks and implications in the scenario of new variants.

With the emergence of new variants of SARS-CoV-2, questions about transmissibility, vaccine efficacy, and impact on mortality are important to support decision-making in public health measures. Modifications related to transmissibility combined with the fact that much of the population has already been partially exposed to infection and/or vaccination, have stimulated recommendations to reduce the isolation period for COVID-19. However, these new guidelines have raised questions about their effectiveness in reducing contamination and minimizing impact in work environments. Therefore, a collaborative task force was developed to review the subject in a non-systematic manner, answering questions about SARS-CoV-2 variants, COVID-19 vaccines, isolation/quarantine periods, testing to end the isolation period, and the use of masks as mitigation procedures. Overall, COVID-19 vaccines are effective in preventing severe illness and death but are less effective in preventing infection in the case of the Omicron variant. Any strategy that is adopted to reduce the isolation period should take into consideration the epidemiological situation of the geographical region, individual clinical characteristics, and mask for source control. The use of tests for isolation withdrawal should be evaluated with caution, due to results depending on various conditions and may not be reliable.

Posicionamento da ASBAI sobre a vacinação de crianças de 5 a 11 anos contra a COVID-19 com a vacina Comirnaty/ Pfizer/BioNTech ­ 27/12/2021 / ASBAI's position on vaccination of children aged 5 to 11 years against COVID-19 with the Comirnaty/Pfizer/BioNTech vaccine ­ 12/27/2021

A Associação Brasileira de Alergia e Imunologia (ASBAI) se manifesta totalmente favorável à imunização contra a COVID-19 em indivíduos entre 5 e 11 anos, para a proteção não somente deste grupo, mas também de seus conviventes. A vacinação de crianças, demonstrada sua eficácia e segurança, é fundamental para o controle da circulação do vírus e proteção de indivíduos cuja resposta vacinal pode não ocorrer de modo eficiente, como os imunocomprometidos e idosos. A imunização de pessoas entre 5 e 11 anos deve ser uma estratégia de saúde pública fundamental para o controle da pandemia que nos assola desde março de 2020 com todas as suas graves consequências para a saúde pública e a economia.

The Brazilian Association of Allergy and Immunology (ASBAI) is totally in favor of immunization against COVID-19 in individuals between 5 and 11 years old, for the protection not only of this group, but also of their cohabitants. The vaccination of children, once its efficacy and safety has been demonstrated, is essential for controlling the circulation of the virus and protecting individuals whose vaccine response may not occur efficiently, such as the immunocompromised and the elderly. The immunization of people between the ages of 5 and 11 must be a fundamental public health strategy to control the pandemic that has been plaguing us since March 2020 with all its serious consequences for public health and the economy.

COVID-19 and isolation: Risks and implications in the scenario of new variants

Abstract With the emergence of new variants of SARS-CoV-2, questions about transmissibility, vaccine efficacy, and impact on mortality are important to support decision-making in public health measures. Modifications related to transmissibility combined with the fact that much of the population has already been partially exposed to infection and/or vaccination, have stimulated recommendations to reduce the isolation period for COVID-19. However, these new guidelines have raised questions about their effectiveness in reducing contamination and minimizing impact in work environments. Therefore, a collaborative task force was developed to review the subject in a non-systematic manner, answering questions about SARS-CoV-2 variants, COVID-19 vaccines, isolation/quarantine periods, testing to end the isolation period, and the use of masks as mitigation procedures. Overall, COVID-19 vaccines are effective in preventing severe illness and death but are less effective in preventing infection in the case of the Omicron variant. Any strategy that is adopted to reduce the isolation period should take into consideration the epidemiological situation of the geographical region, individual clinical characteristics, and mask for source control. The use of tests for isolation withdrawal should be evaluated with caution, due to results depending on various conditions and may not be reliable.

Common variable immunodeficiency: an important but little-known risk factor for gastric cancer.

INTRODUCTION: although it is a rare disease, common variable immunodeficiency (CVID) stands out as the most frequent primary symptomatic immunodeficiency. Carriers are prone to a variety of recurrent bacterial infections, in addition to the risk of developing autoimmune diseases and neoplasms including gastric cancer (GC). Despite the recognized risk, there are no specific standardized protocols for the management of GC in these patients, so the reported oncological results are varied. Thus, this study aims to describe the clinicopathological characteristics and prognosis of patients with CVID undergoing surgical treatment of GC. METHODS: all patients with GC undergoing surgical treatment between 2009 and 2020 were retrospectively evaluated. Later, patients diagnosed with CVID were identified and this group was compared with the remaining patients without any immunodeficiency. RESULTS: among the 1101 patients with GC evaluated in the period, 10 had some type of immunodeficiency, and 5 were diagnosed with CVID. Patients with CVID had younger age, lower BMI, and smaller lesions compared to those without CVID. Four patients underwent curative gastrectomy and one patient underwent jejunostomy. Two patients died (1 palliative and 1 curative) and one patient had disease recurrence. There was no statistically significant difference regarding the incidence of postoperative complications and survival between the evaluated groups. CONCLUSION: the CVID incidence in patients with GC undergoing surgical treatment was 0.5%, occurring at a less advanced age, but with no difference regarding surgical and oncological results.

Vacinas COVID-19 e outros imunobiológicos ­ intervalos preconizados / COVID-19 vaccines and other immunobiological drugs ­ recommended intervals

Com o início do programa de vacinação contra a COVID-19 no Brasil, surgiu uma série de questionamentos relacionados ao uso dos imunizantes. Neste documento, o grupo de estudo da COVID-19 da Associação Brasileira de Alergia e Imunologia (ASBAI) avalia as evidências científicas e se posiciona em relação aos intervalos preconizados entre a administração das vacinas contra o SARS-CoV-2 e dos imunobiológicos.

With the beginning of the COVID-19 vaccination program in Brazil, a series of questions related to the use of vaccines arose. In this document, the COVID-19 study group of the Brazilian Association of Allergy and Immunology (ASBAI) assesses the scientific evidence and takes a stand for the recommended intervals between the administration of SARS-CoV-2 vaccines and that of immunobiological drugs.

Reinfecções pelo SARS-CoV-2: fato ou fake ? Implicações para a resposta vacinal / Reinfection with SARS-CoV-2: fact or fake? Implications for vaccine response

Há evidências atuais de que a reinfecção pelo SARS-CoV-2 é uma realidade, mas na grande maioria das situações não houve investigação que permitisse sua perfeita caracterização, sendo confirmados poucos casos. Em situações de real reinfecção, esta ocorreu, em sua grande maioria, por variantes do vírus, com diversas mutações, usualmente na proteína da espícula viral, em profissionais de saúde altamente expostos, ou em portadores de imunodeficiências, tanto primárias quanto secundárias. Ressaltamos que as vacinas podem ser modificadas com relativa facilidade, mas a capacidade de fabricação e de distribuição pelo mundo será capaz de acompanhar a demanda por vacinação em massa de forma eficiente? Neste manuscrito, a comissão de estudo da COVID-19 da ASBAI analisa criticamente o conhecimento atual sobre a reinfecção pelo SARS-CoV-2.

There is current evidence that reinfection with SARS-CoV-2 is a reality, but there is also a lack of investigation that would allow its perfect characterization, and few cases have been confirmed. Real reinfections occurred mostly with variants of the virus, with several mutations, usually in the viral spike protein, in highly exposed health professionals or in patients with immunodeficiencies, both primary and secondary. We emphasize that vaccines can be modified relatively easily, but will the manufacturing and distribution capacity around the world be able to keep up with the demand for mass vaccination efficiently? The ASBAI COVID-19 study commission critically analyzes in this manuscript the current knowledge about SARS-CoV-2 reinfection.

Alergias e vacinas contra a COVID-19 / Allergies and vaccines against COVID-19

As vacinas são reconhecidas como uma das conquistas do século passado de maior impacto em Saúde Pública, reduzindo de modo significativo a morbidade e mortalidade associadas a grande número de doenças infecciosas. No entanto, em casos raros, as vacinas podem causar doença ou eventos adversos pós-vacinação (EAPV). Os imunologistas clínicos e alergistas possuem um papel muito importante nesse momento em que mundialmente buscamos imunizar a população contra a COVID- 19. Eles devem fornecer apoio aos indivíduos orientando sobre o diagnóstico e tratamento de EAPV, incluindo anafilaxia, e, ainda, apoiar e encorajar os pacientes a se vacinarem, mesmo após eventos adversos, desde que leves ou moderados.

Vaccines are known as one of the achievements of the last century with greatest impact on public health, significantly reducing morbidity and mortality associated with a large number of infectious diseases. However, in rare cases, vaccines may cause disease or adverse events following immunization. Clinical immunologists and allergists have a very important role in the worldwide vaccination against COVID-19. They should provide support to individuals by advising on the diagnosis and treatment of adverse events following immunization, including anaphylaxis, and also support and encourage patients to be vaccinated, even after adverse events, as long as they are mild or moderate.

Vacinas contra a COVID-19 e os erros inatos da imunidade (ou imunodeficiências primárias) / COVID-19 vaccines and inborn errors of immunity (or primary immunodeficiencies)

Desde o início da pandemia de COVID-19 iniciou-se a corrida por uma imunização ativa, eficaz e segura. Todas as vacinas desenvolvidas até o momento vêm demostrando boa eficácia na prevenção de casos graves de COVID-19, de hospitalizações e mortes. Muitos pacientes com erros inatos da imunidade (EII) não terão capacidade de desenvolver uma resposta imune semelhante ao indivíduo imunocompetente. Esses pacientes foram incluídos nos grupos prioritários definidos pelo Ministério da Saúde, como pessoas entre 18 a 59 anos com uma ou mais das comorbidades, incluindo as imunodeficiências primárias. Eles podem e devem receber as vacinas em uso contra o SARS-CoV-2, mas nem sempre apresentarão uma resposta imunológica satisfatória e protetora, e, portanto, seus contactantes também devem ser vacinados.

Since the beginning of the COVID-19 pandemic, the race for an active, effective, and safe immunization has started. All vaccines developed to date have shown good efficacy in preventing serious cases of COVID-19, hospitalization, and death. Many patients with inborn errors of immunity will not be able to develop an immune response similar to that of immunocompetent individuals. These patients were included in the priority groups defined by the Brazilian Ministry of Health, as people between 18 and 59 years of age with one or more comorbidities, including primary immunodeficiencies. They can and should receive the vaccines in use against SARS-CoV-2, but they will not always have a satisfactory and protective immune response, and, therefore, those in direct contact with them should also be vaccinated.

Vacina contra a febre amarela: reações adversas e populações de risco / Yellow fever vaccine: adverse reactions and at-risk populations

A febre amarela é uma doença infecciosa grave causada por um arbovírus e transmitida pelos mosquitos Haemagogus (ciclo silvestre) e Aedes aegypti (ciclo urbano). Os sintomas mais comuns são febre, calafrios, cefaleia, mialgia e náuseas. Uma parcela dos pacientes desenvolve as formas graves, que podem cursar com insuficiência hepática e renal. A partir de 2014 a febre amarela passou a ser endêmica em áreas extra-amazônicas, tornando-se um grave problema de saúde pública. Por isso, a vacinação contra a febre amarela é essencial para o controle da doença no Brasil, tornando-se a medida mais eficaz, com imunogenicidade superior a 95%. Em relação à segurança, a maioria dos eventos adversos após a vacinação são locais, e os eventos adversos graves, como a encefalite pós-vacinal, são relatados principalmente em idosos e imunossuprimidos. Por se tratar de vacina de vírus vivo atenuado, é recomendada cautela na sua indicação nesses indivíduos. Outra preocupação em relação à segurança se deve ao fato de que, por ser cultivada em ovos embrionados de galinha (maior quantidade de proteínas do ovo), a vacina febre amarela é contraindicada em indivíduos que apresentam história prévia de reação anafilática ao ovo. No entanto, diante do cenário epidemiológico atual, indivíduos com história de hipersensibilidade leve ou moderada ao ovo podem recebê-la seguindo as recomendações de segurança revisadas e sugeridas neste texto. O objetivo deste documento foi revisar as indicações e contraindicações da vacina febre amarela e apresentar uma abordagem prática em situações especiais, com a finalidade de garantir a imunização à população de risco.

Yellow fever is a serious infectious disease caused by arboviruses and transmitted by Haemagogus (wild cycle) and Aedes aegypti (urban cycle) mosquitoes. The most common symptoms are fever, chills, headache, myalgia and nausea. A subgroup of patients develops severe forms that can manifest with hepatic and renal failure. As of 2014, yellow fever has become endemic in extra- Amazonian areas, and therefore it is considered a serious public health problem. Vaccination against yellow fever is essential to control the disease in Brazil, and it is the most effective measure, with an immunogenicity above 95%. With regard to safety, most post-vaccination adverse reactions are local, and serious adverse events such as post-vaccinal encephalitis are reported mainly in the elderly and in immunocompromised hosts. Because the yellow fever vaccine is live attenuated, caution is advised in these individuals. Another concern regarding safety is the fact that the vaccine is cultured in embryonated chicken eggs (high amount of egg protein), contraindicating its use in individuals with a history of anaphylactic reaction to egg. However, in view of the current epidemiological scenario, individuals with a history of mild or moderate hypersensitivity to egg may receive the vaccine, observing the safety recommendations reviewed and suggested in this paper. The objective of this article is to review indications and contraindications of the yellow fever vaccine and present a practical approach in special situations to guarantee immunization of the population at risk.