Strategies for expanding childhood vaccination in the Americas following the COVID-19 pandemic.

Objective: To provide an overview of the status of the childhood vaccination schedule in the Americas, outline program structures, and identify updated implementation strategies to improve vaccination coverage following the COVID-19 pandemic. Methods: A group of experts in pediatrics, epidemiology, vaccines, and global and public health discussed the current status of the childhood vaccination schedule in the Americas, describing the program structure and identifying new implementation strategies that have the potential to improve vaccination coverage in the post-pandemic context, after the challenges COVID-19 presented for more than two years. Results: The Americas currently face a high risk of resurgence of diseases that were previously controlled or eliminated. Therefore, it is important to find new strategies to educate citizens on the risks associated with lower vaccination rates, especially in children. Conclusions: New strategies along with strong mobilization of the population and advocacy by citizens are necessary to prevent antivaccination groups from gaining a stronger presence in the region and jeopardizing the credibility of the Expanded Program on Immunization.

Frequency of human papilomavirus and associated factors in gypsy and quilombola women : Human papillomavirus in gypsy and quilombola women.

BACKGROUND: The prevalence of Human Papillomavirus (HPV) infection in the general population is widely known, however, there are still few studies related to this infection in minority groups, Thus, the objective is to analyze the frequency of human papillomavirus and associated factors in quilombola and gypsy women. METHODS: Cross-sectional research with 145 quilombola and gypsy women from Caxias, Maranhão. Two Pap smear collections were performed and a questionnaire with 46 questions was applied between January, 2020 and March, 2021. Descriptive analysis and Odds Ratio with 95% confidence interval were performed. The research was approved by the ethics committee. RESULTS: There were 09 cases of atypia. The frequency of human papillomavirus was 41.37%, with a higher risk in quilombolas 55 (91.70%). Multiple infections were prevalent (53%) with high-risk genotypes 21 (35%). Types 16 and 18 together accounted for 42.85% of cases. CONCLUSIONS: The frequency of human papillomavirus infection was higher than those recorded in the Northeast and Brazil, and therefore type 16 predominated. Due to limitations, the virus lineages and sublineages were not evaluated. Quilombola women had a higher rate of infection than gypsies.

Vaccination in Pediatric Patients with Sickle-Cell Disease: Uptake Report and Mini-Review.

BACKGROUND: Brazil has one of the highest numbers of births with sickle-cell disease (SCD) in the Americas. Despite the risk of severe illnesses and death due to both vaccine-preventable infections, vaccination uptake in pediatric patients with SCD is unknown. MATERIAL AND METHODS: Children under 18 years with SCD presenting to routine medical consultations had their vaccination status evaluated according to the national recommendations. Data obtained were classified as 'Adequate', 'Delayed' or 'Missing' vaccination and compared among age groups. RESULTS: From 117 children screened, 100 had their vaccination card available. Vaccination coverage of routine vaccines was above 95% for all primary series and both age groups, with varied rates of delays and low missing doses. Among SCD extended vaccination, the most frequently delayed and missed vaccines were those specifically recommended to individuals with SCD as per national guidelines-and particularly those against encapsulated bacteria. Significant and varied rates of missing doses occurred in primary series and booster doses for PPSV23, Hib, menC, hepatitis A and varicella. The average influenza vaccination rate was 69.5%, with higher rates among younger children. CONCLUSIONS: Children with SCD have alarming under-vaccination rates. Basic prevention strategies in Brazil should be reassessed in this specific population.

High prevalence of SARS-CoV-2 infection among symptomatic healthcare workers in a large university tertiary hospital in São Paulo, Brazil.

BACKGROUND: Brazil became the epicenter of the COVID-19 pandemic in Latin America since May 2020, reporting the highest number of cases and deaths in the region. Healthcare workers (HCWs) are at increased risk of SARS-CoV-2 infection, experiencing a significant burden from COVID-19. Identifying and understanding the clinical characteristics and risk factors associated with infection are of paramount importance to inform screening strategies and infection control practices in this scenario. The aims of this study were to investigate the prevalence and clinical characteristics of HCWs with COVID-19 symptoms. METHODS: Between March 21st and May 22nd, 2020 a cross-sectional study was performed in a tertiary university hospital in São Paulo. Prevalence of SARS-CoV-2 infection among HCWs with COVID-19 symptoms was determined by RT-PCR testing on nasopharyngeal and oropharyngeal samples. Participants were asked to complete an electronic structured questionnaire including clinical and demographic data. RESULTS: Overall, 125 (42.37%) of 295 symptomatic HCWs tested positive for SARS-CoV-2. Over the 10-week study period, positivity rates varied from 22.2% (95% CI 15.9-60.3%) in the second week to 55.9% (95% CI 43.2-68.6%) in the sixth week, reaching a plateau (38-46%) thereafter. Median (SD) age was 34.2 (9.9) years and 205 (69.5%) were female. We did not find significant differences in the prevalence of the most commonly reported underlying medical condition among healthcare workers that tested positive or negative for SARS-CoV-2 infection. After multivariable analysis, using logistic regression, anosmia (adjusted OR 4.4 95% CI 2.21-8.74) and ocular pain (adjusted OR 1.95 95% CI 1.14-3.33) were the only symptoms independently associated with positivity for SARS-CoV-2 infection. Follow-up information on clinical outcomes showed that 9 (7.2%) HCWs were hospitalized (seven were male) and 2 (1.6%) died. CONCLUSIONS: The findings of this study confirmed the high burden of SARS-CoV-2 infection among healthcare workers in the hardest hit city by the pandemic in Latin America. Anosmia and ocular pain were symptoms independently associated with COVID-19 diagnosis. In low and middle-income countries, where limited availability of tests is frequent, these findings may contribute to optimize a targeted symptom-oriented screening strategy.

Identification of Serologic Markers for School-Aged Children With Congenital Rubella Syndrome.

BACKGROUND: Congenital rubella syndrome (CRS) case identification is challenging in older children since laboratory markers of congenital rubella virus (RUBV) infection do not persist beyond age 12 months. METHODS: We enrolled children with CRS born between 1998 and 2003 and compared their immune responses to RUBV with those of their mothers and a group of similarly aged children without CRS. Demographic data and sera were collected. Sera were tested for anti-RUBV immunoglobulin G (IgG), IgG avidity, and IgG response to the 3 viral structural proteins (E1, E2, and C), reflected by immunoblot fluorescent signals. RESULTS: We enrolled 32 children with CRS, 31 mothers, and 62 children without CRS. The immunoblot signal strength to C and the ratio of the C signal to the RUBV-specific IgG concentration were higher (P < .029 for both) and the ratio of the E1 signal to the RUBV-specific IgG concentration lower (P = .001) in children with CRS, compared with their mothers. Compared with children without CRS, children with CRS had more RUBV-specific IgG (P < .001), a stronger C signal (P < .001), and a stronger E2 signal (P ≤ .001). Two classification rules for children with versus children without CRS gave 100% specificity with >65% sensitivity. CONCLUSIONS: This study was the first to establish classification rules for identifying CRS in school-aged children, using laboratory biomarkers. These biomarkers should allow improved burden of disease estimates and monitoring of CRS control programs.

Prevalence and Incidence of Respiratory Syncytial Virus and Other Respiratory Viral Infections in Children Aged 6 Months to 10 Years With Influenza-like Illness Enrolled in a Randomized Trial.

BACKGROUND: The high burden of respiratory syncytial virus (RSV)-associated morbidity and mortality makes vaccine development a priority. METHODS: As part of an efficacy trial of pandemic influenza vaccines (NCT01051661), RSV epidemiology in healthy children aged 6 months to <10 years at first vaccination with influenza-like illness (ILI) was evaluated in Australia, Brazil, Colombia, Costa Rica, Mexico, the Philippines, Singapore, and Thailand between February 2010 and August 2011. Active surveillance for ILI was conducted for approximately 1 year, with nasal and throat swabs analyzed by polymerase chain reaction. The prevalence and incidence of RSV among ILI episodes were calculated. RESULTS: A total of 6266 children were included, of whom 2421 experienced 3717 ILI episodes with a respiratory sample available. RSV was detected for 359 ILI episodes, a prevalence of 9.7% (95% confidence interval: 8.7-10.7). The highest prevalence was in children aged 12-23 or 24-35 months in all countries except the Philippines, where it was in children aged 6-11 months. The incidence of RSV-associated ILI was 7.0 (6.3-7.7) per 100 person-years (PY). Eighty-eight ILI episodes resulted in hospitalization, of which 8 were associated with RSV (prevalence 9.1% [4.0-17.1]; incidence 0.2 [0.1-0.3] per 100 PY). The incidence of RSV-associated ILI resulting in medical attendance was 6.0 (5.4-6.7) per 100 PY. RSV B subtypes were observed more frequently than A subtypes. CONCLUSIONS: Active surveillance demonstrated the considerable burden of RSV-associated illness that would not be identified through hospital-based surveillance, with a substantial part of the burden occurring in older infants and children.

Molecular characterisation of the NSP4 gene of group A human rotavirus G2P[4] strains circulating in São Paulo, Brazil, from 1994 and 2006 to 2010.

Group A human rotaviruses (HuRVA) are causative agents of acute gastroenteritis. Six viral structural proteins (VPs) and six nonstructural proteins (NSPs) are produced in RV-infected cells. NSP4 is a diarrhoea-inducing viral enterotoxin and NSP4 gene analysis revealed at least 15 (E1-E15) genotypes. This study analysed the NSP4 genetic diversity of HuRVA G2P[4] strains collected in the state of São Paulo (SP) from 1994 and 2006-2010 using reverse transcription-polymerase chain reaction, sequencing and phylogenetic analysis. Forty (97.6%) G2P[4] strains displayed genotype E2; one strain (2.4%) displayed genotype E1. These results are consistent with the proposed linkage between VP4/VP7 (G2P[4]) and the NSP4 (E2) genotype of HuRVA. NSP4 phylogenetic analysis showed distinct clusters, with grouping of most strains by their genotype and collection year, and most strains from SP were clustered together with strains from other Brazilian states. A deduced amino acid sequence alignment for E2 showed many variations in the C-terminal region, including the VP4-binding domain. Considering the ability of NSP4 to generate host immunity, monitoring NSP4 variations, along with those in the VP4 or VP7 protein, is important for evaluating the circulation and pathogenesis of RV. Finally, the presence of one G2P[4]E1 strain reinforces the idea that new genotype combinations emerge through reassortment and independent segregation.

Relative efficacy of AS03-adjuvanted pandemic influenza A(H1N1) vaccine in children: results of a controlled, randomized efficacy trial.

BACKGROUND: The vaccine efficacy (VE) of 1 or 2 doses of AS03-adjuvanted influenza A(H1N1) vaccine relative to that of 2 doses of nonadjuvanted influenza A(H1N1) vaccine in children 6 months to <10 years of age in a multinational study conducted during 2010-2011. METHODS: A total of 6145 children were randomly assigned at a ratio of 1:1:1 to receive 2 injections 21 days apart of A/California/7/2009(H1N1)-AS03 vaccine at dose 1 and saline placebo at dose 2, 2 doses 21 days apart of A/California/7/2009(H1N1)-AS03 vaccine (the Ad2 group), or 2 doses 21 days apart of nonadjuvanted A/California/7/2009(H1N1) vaccine (the NAd2 group). Active surveillance for influenza-like illnesses continued from days 14 to 385. Nose and throat samples obtained during influenza-like illnesses were tested for A/California/7/2009(H1N1), using reverse-transcriptase polymerase chain reaction. Immunogenicity, reactogenicity, and safety were assessed. RESULTS: There were 23 cases of confirmed 2009 pandemic influenza A(H1N1) (A[H1N1]pdm09) infection for the primary relative VE analysis. The VE in the Ad2 group relative to that in the NAd2 group was 76.8% (95% confidence interval, 18.5%-93.4%). The benefit of the AS03 adjuvant was demonstrated in terms of the greater immunogenicity observed in the Ad2 group, compared with the NAd2 group. CONCLUSION: The 4-8-fold antigen-sparing adjuvanted pandemic influenza vaccine demonstrated superior and clinically important prevention of A(H1N1)pdm09 infection, compared with nonadjuvanted vaccine, with no observed increase in medically attended or serious adverse events. These data support the use of adjuvanted influenza vaccines during influenza pandemics. Clinical Trials Registration. NCT01051661.

Carriage rate and effects of vaccination after outbreaks of serogroup C meningococcal disease, Brazil, 2010.

During 2010, outbreaks of serogroup C meningococcal (MenC) disease occurred in 2 oil refineries in São Paulo State, Brazil, leading to mass vaccination of employees at 1 refinery with a meningococcal polysaccharide A/C vaccine. A cross-sectional study was conducted to assess the prevalence of meningococci carriage among workers at both refineries and to investigate the effect of vaccination on and the risk factors for pharyngeal carriage of meningococci. Among the vaccinated and nonvaccinated workers, rates of overall meningococci carriage (21.4% and 21.6%, respectively) and of MenC carriage (6.3% and 4.9%, respectively) were similar. However, a MenC strain belonging to the sequence type103 complex predominated and was responsible for the increased incidence of meningococcal disease in Brazil. A low education level was associated with higher risk of meningococci carriage. Polysaccharide vaccination did not affect carriage or interrupt transmission of the epidemic strain. These findings will help inform future vaccination strategies.

Antibody persistence and revaccination recommendations of MenACWY-TT: a review of clinical studies assessing antibody persistence up to 10 years after vaccination.

INTRODUCTION: Invasive meningococcal disease (IMD) is potentially fatal and associated with severe sequelae among survivors. It is preventable by several vaccines, including meningococcal vaccines targeting the most common disease-causing serogroups (A, B, C, W, Y). The meningococcal ACWY tetanus toxoid conjugate vaccine (MenACWY-TT [Nimenrix]) is indicated from 6 weeks of age in the European Union and >50 additional countries. AREAS COVERED: Using PubMed, Google Scholar, ClinicalTrials.gov and ad hoc searches for publications to June 2023, we review evidence of antibody persistence for up to 10 years after primary vaccination and up to 6 years after MenACWY-TT revaccination. We also review global MenACWY revaccination recommendations and real-world impact of vaccination policies, focusing on how these data can be considered alongside antibody persistence data to inform future IMD prevention strategies. EXPERT OPINION: Based on clear evidence that immunogenicity data (demonstrated antibody titers above established correlates of protection) are correlated with real-world effectiveness, long-term persistence of antibodies after MenACWY-TT vaccination suggests continuing protection against IMD. Optimal timing of primary and subsequent vaccinations is critical to maximize direct and indirect protection. Recommending bodies should carefully consider factors such as age at vaccination and long-term immune responses associated with the specific vaccine being used.

Safety and immunogenicity of co-administered meningococcal serogroup B (4CMenB) vaccine: A literature review.

The four-component meningococcal serogroup B vaccine (4CMenB) is indicated for the prevention of invasive meningococcal disease (IMD) caused by Neisseria meningitidis serogroup B. Co-administering 4CMenB with other vaccines may improve vaccine uptake provided that the safety and immunogenicity of either are not affected. Published literature on the immunogenicity and reactogenicity of 4CMenB co-administered with other routine childhood and adulthood vaccines was reviewed. From 282 publications identified, data were collated from 10 clinical studies, 3 real-world studies, and 3 reviews. The evidence showed that 4CMenB co-administration is not associated with significant safety concerns or clinically relevant immunological interferences. The increased reactogenicity (e.g., fever) associated with 4CMenB co-administration can be adequately managed with prophylactic paracetamol in children. Thus, 4CMenB co-administration has the potential to maximize vaccine coverage and improve protection against IMD globally.

Epidemiology of Meningococcal Disease in Four South American Countries and Rationale of Vaccination in Adolescents from the Region: Position Paper of the Latin American Society of Pediatric Infectious Diseases (SLIPE).

Surveillance of meningococcal disease (MD) is crucial after the implementation of vaccination strategies to monitor their impact on disease burden. Adolescent vaccination could provide direct and indirect protection. Argentina, Brazil, and Chile have introduced meningococcal conjugate vaccines (MCV) into their National Immunization Programs (NIP), while Uruguay has not. Here, we analyze the epidemiology of MD and vaccination experience from these four South American countries to identify needs and plans to improve the current vaccination programs. METHODOLOGY: Descriptive study of MD incidence rates, serogroup distribution, case fatality rates (CFR), and MCV uptakes during the period 2010-2021 in Argentina, Brazil, Chile, and Uruguay. Data were extracted from national surveillance programs, reference laboratories, NIPs, and Pubmed. RESULTS: MD overall incidence from 2010 to 2021 have a decreasing trend in Argentina (0.37 [IQR = 0.20-0.61]), Brazil (0.59 [IQR = 0.54-1.22]), and Chile (0.45 [IQR = 0.40-0.77]), while a significant increase in Uruguay (0.47 [IQR = 0.33-0.69]) was found from 2016 to 2019. During the COVID-19 pandemic, all countries sharply reduced their MD incidence. The highest incidence rates were observed among infants, followed by children 1-4 years of age. No second peak was evident in adolescents. A reduction in serogroup C, W, and Y cases has occurred in Argentina, Brazil, and Chile after introduction of MCV, serogroup B becoming predominant in all four countries. Median CFR was 9.0%, 21%, 19.9%, and 17.9% in Argentina, Brazil, Chile, and Uruguay, respectively. Median uptake of MCV for Argentina and Brazil were 66.6% and 91.0% for priming in infants; 54.7% and 84.5% for booster in toddlers; and 47.5% and 53% for adolescents; while for Chile, 95.6% for toddlers. CONCLUSIONS: Experience after the implementation of MCV programs in South America was successful, reducing the burden of MD due to the vaccine serogroups. High vaccine uptake and the inclusion of adolescents will be crucial in the post-pandemic period to maintain the protection of the population. The increase in the proportion of serogroup B cases emphasizes the importance of continuous surveillance to guide future vaccination strategies.

Pandemic's influence on parents' attitudes and behaviors toward meningococcal vaccination.

Invasive meningococcal disease is a life-threatening infection preventable through vaccination. Pediatric vaccination rates have declined during the coronavirus disease 2019 (COVID-19) pandemic. This survey aimed to understand how parents' attitudes and behaviors have changed during the pandemic with regard to immunization and, more specifically, meningococcal vaccination. An online survey was emailed to parents of eligible children 0-4 years, following the selection process from UK, France, Germany, Italy, Brazil, Argentina, and Australia; and of adolescents 11-18 years from US. Data collection took place 19 January-16 February 2021. Quotas were set to ensure a representative sample. Eleven questions relating to general perceptions around vaccination and attitudes and behaviors toward meningitis vaccination were displayed. On 4,962 parents (average 35 years) participating in the survey, most (83%) believed important for their child to continue receiving recommended vaccines during the COVID-19 pandemic. Nearly half of routine vaccine appointments were delayed or canceled due to the pandemic, and 61% of respondents were likely to have their children catch up once COVID-19 restrictions were lifted. 30% of meningitidis vaccination appointments were canceled or delayed during the pandemic, and 21% of parents did not intend to reschedule them because of lockdown/stay at home regulations, and fear of catching COVID-19 in public places. It is crucial to communicate clear instructions to health workers and the general population and to provide appropriate safety precautions in vaccination centers. This will help to maintain vaccination rates and limit infections to prevent future outbreaks.

What is the context? Invasive meningococcal disease (IMD) is an uncommon infection that can lead to permanent disabilities and even death.Meningitis vaccination can prevent IMDs caused by Neisseria meningitidis.Vaccination rates have declined during the coronavirus (COVID-19) pandemic.What is new? We collected opinion of parents from the UK, France, Germany, Italy, Brazil, Argentina, Australia, and the US, to understand their attitudes and behaviors toward meningitis vaccination during the COVID-19 pandemic.Results were reviewed by health care professional experts as well as by patient authors (IMD survivors).Most (83%) of the 4,962 parents believed that it is important for their child to continue receiving recommended vaccines during the COVID-19 pandemic.Half of the scheduled appointments for meningitis vaccination were canceled or delayed during the COVID-19 pandemic, mainly due to lockdown regulations and fear of catching COVID-19.Twenty-one percent of the parents who had their child's meningitis vaccination appointment canceled, did not intend to reschedule it.What is the impact? It is crucial that clear information is communicated by health care authorities and practitioners about the availability of vaccination during pandemic and the safety precautions that are taken.Collected opinions emphasize the importance of continuing vaccinations against infectious diseases during a pandemic.

Chronic medical conditions associated with invasive pneumococcal diseases in inpatients in teaching hospitals in São Paulo city: Estimating antimicrobial susceptibility and serotype-coverage of pneumococcal vaccines.

BACKGROUND: Chronic conditions increase the risk of invasive pneumococcal diseases (IPD). Pneumococcal vaccination remarkably reduced IPD morbimortality in vulnerable populations. In Brazil, pneumococcal vaccines are included in the National Immunization Program (PNI): PCV10 for < 2 years-old, and PPV23 for high risk-patients aged ≥ 2 years and institutionalized ≥ 60 years. PCV13 is available in private clinics and recommended in the PNI for individuals with certain underlying conditions. METHODS: A retrospective study was performed using clinical data from all inpatients from five hospitals with IPD from 2016 to 2018 and the corresponding data on serotype and antimicrobial-non-susceptibility of pneumococcus. Vaccine-serotype-coverage was estimated. Patients were classified according to presence of comorbidities: healthy, without comorbidities; at-risk, included immunocompetent persons with specific medical conditions; high-risk, with immunocompromising conditions and others RESULTS: 406 IPD cases were evaluated. Among 324 cases with information on medical conditions, children < 5 years were mostly healthy (55.9%), while presence of comorbidity prevailed in adults ≥ 18 years old (> 82.0%). Presence of ≥1 risk condition was reported in ≥ 34.8% of adults. High-risk conditions were more frequent than at-risk in all age groups. Among high-risk comorbidity (n = 211), cancer (28%), HIV/AIDS (25.7%) and hematological diseases (24.5%) were the most frequent. Among at-risk conditions (n = 89), asthma (16.5%) and diabetes (8.1%) were the most frequent. Among 404 isolates, 42.9% belonged to five serotypes: 19A (14.1%), 3 (8.7%), 6C (7.7%), 4 and 8 (6.2% each); 19A and 6C expressed antimicrobial-non-susceptibility. The vaccine-serotype-coverage was: PCV10, 19.1%, PCV13, 43.8%; PCV15, 47.8%; PCV20, 62.9%; PCV21, 65.8%, and PPV23, 67.3%. Information on hospital outcome was available for 283 patients, of which 28.6% died. Mortality was 54.2% for those with meningitis. CONCLUSION: Vaccine with expanded valence of serotypes is necessary to offer broad prevention to IPD. The present data contribute to pneumococcal vaccination public health policies for vulnerable patients, mainly those with comorbidity and the elderly.

Narrative Review of the Evolution of COVID-19 Vaccination Recommendations in Countries in Latin America, Africa and the Middle East, and Asia.

The rapid rollout of vaccines to combat the coronavirus disease 2019 (COVID-19) pandemic over the past 2 years has resulted in the use of various vaccine platforms and regional differences in COVID-19 vaccine implementation strategies. The aim of this narrative review was to summarize evolving COVID-19 vaccine recommendations in countries in Latin America, Asia, and Africa and the Middle East across various vaccine platforms, age groups, and specific subpopulations. Nuances in primary and booster vaccination schedules were evaluated, and the preliminary impact of such diverse vaccination strategies are discussed, including key vaccine effectiveness data in the era of Omicron-lineage variants. Primary vaccination rates for included Latin American countries were 71-94% for adults and between 41% and 98% for adolescents and children; rates for first booster in adults were 36-85%. Primary vaccination rates for adults in the included Asian countries ranged from 64% in the Philippines to 98% in Malaysia, with corresponding booster rates varying from 9% in India to 78% in Singapore; for adolescents and children, primary vaccination rates ranged from 29% in the Philippines to 93% in Malaysia. Across included African and Middle Eastern countries, primary vaccination rates in adults varied widely from 32% in South Africa to 99% in the United Arab Emirates; booster rates ranged from 5% in South Africa to 60% in Bahrain. Evidence from the regions studied indicates preference of using an mRNA vaccine as a booster on the basis of safety and effectiveness of observed real-world data, especially during circulation of Omicron lineages. Vaccination against COVID-19 remains of paramount importance to reduce the burden of disease; strategies to overcome vaccine inequity, fatigue, hesitancy, and misinformation and to ensure adequate access and supply are also important.

Characteristics and clinical outcomes of COVID-19 in children: a hospital-based surveillance study in Latin America's hardest-hit city.

Background: In 2020, Brazil became the epicentre of the coronavirus disease (COVID-19) pandemic in Latin America, resulting in an unparalleled health catastrophe. Nevertheless, comprehensive clinical reports in Brazilian children are not available. Methods: This retrospective, hospital-based, active surveillance study was performed to identify paediatric patients with COVID-19 who presented at a private academic medical centre in a large urban area between March 2020 and March 2021. Clinical and demographic information was analysed for those requiring hospitalization, those with severe illness and those with clinical syndromes. Results: In total, 964 symptomatic cases were evaluated; of these, 17.7% required hospitalization, and 27.5% of hospitalized cases were classified as severe/critical. Acute bronchiolitis and pneumonia were the most common causes of hospitalization among the severe cases. Twenty-seven hospitalized children fulfilled the diagnostic criteria for multi-system inflammatory syndrome (median age 29 months; 85.2% cases were non-severe). A significant co-existing condition was present in 29% of hospitalized children. The risk of hospitalization was higher in children with at least one comorbidity, children aged <2 years and obese children. Increased risk of severe disease was described among those with leukopenia, leukocytosis or any significant comorbidity. No deaths occurred among the study population. Conclusion: Although most children with COVID-19 experienced mild disease, and no deaths occurred among the study population, a significant proportion of cases required hospitalization and developed severe illness. Obesity, young age, underlying comorbidity, leukopenia and leukocytosis were risk factors for hospitalization or severe disease.

Expert review of global real-world data on COVID-19 vaccine booster effectiveness and safety during the omicron-dominant phase of the pandemic.

INTRODUCTION: COVID-19 vaccines have been highly effective in reducing morbidity and mortality during the pandemic. However, the emergence of the Omicron variant and subvariants as the globally dominant strains have raised doubts about the effectiveness of currently available vaccines and prompted debate about potential future vaccination strategies. AREAS COVERED: Using the publicly available IVAC VIEW-hub platform, we reviewed 52 studies on vaccine effectiveness (VE) after booster vaccinations. VE were reported for SARS-CoV-2 symptomatic infection, severe disease and death and stratified by vaccine schedule and age. In addition, a non-systematic literature review of safety was performed to identify single or multi-country studies investigating adverse event rates for at least two of the currently available COVID-19 vaccines. EXPERT OPINION: Booster shots of the current COVID-19 vaccines provide consistently high protection against Omicron-related severe disease and death. Additionally, this protection appears to be conserved for at least 3 months, with a small but significant waning after that. The positive risk-benefit ratio of these vaccines is well established, giving us confidence to administer additional doses as required. Future vaccination strategies will likely include a combination of schedules based on risk profile, as overly frequent boosting may be neither beneficial nor sustainable for the general population.

High Fatality Rates in Pediatric Multisystem Inflammatory Syndrome: A Multicenter Experience From the Epicenter of Brazil's Coronavirus Pandemic.

BACKGROUND: Brazil´s case fatality rate (CFR) of pediatric multisystem inflammatory syndrome in children and adolescents (MIS-C) is among the highest worldwide. Despite these concerns, limited hospital-based and comprehensive pediatric data have been published on MIS-C in Brazilian children. METHODS: We performed a descriptive analysis of the MIS-C scores in 16 public and private hospitals providing secondary and tertiary care in the metropolitan area of São Paulo, Brazil. Clinical and demographic information were systematically extracted from the electronic medical records of each patient. Logistic regression analysis was performed to identify the combined effects of MIS-C phenotype, disease severity and comorbidity as dependent variables. RESULTS: A total of 101 patients met the MIS-C criteria and were evaluated. The median age was 67 months, 60% were male, 28.7% were black or afrodescendant and 62.3% were admitted to public hospitals. Underlying medical conditions were observed in 16.8% of patients and were associated with a longer duration of hospitalization. A Kawasaki disease-like phenotype was observed in 43.5% of patients, and they demonstrated a trend of lower median age. Children with severe MIS-C were older (median age 91 months vs. 36 months) and had a nonspecific phenotype, more cardiovascular and respiratory involvement and kidney injury; 73.3% required intensive care, 20.8% required mechanical ventilation and 35.6% required inotropic support. Four deaths occurred (CFR = 3.9%), three of which were in healthy participants. CONCLUSION: We identified a lower median age, particularly among children with Kawasaki disease-like phenotypes, those with a significant need for intensive care, and a high CFR in MIS-C. Our findings confirmed the increased severity of the disease in the selected Brazilian population.