Helena Brenes-Chacon

Background: Costa Rica introduced universal one-dose varicella vaccination in 2007 using a one-dose schedule administered at 15 months of age through the Costa Rican Social Security Fund (CCSS). A previous national study described epidemiological changes through 2014 by comparing pre- and post-vaccination periods; however, contemporary data on subsequent patterns and residual disease burden are limited. We characterized varicella epidemiology and healthcare burden in Costa Rica using the most recent nationally available data. Methods: We conducted a nationwide retrospective descriptive study using aggregated surveillance and administrative data. Outcomes included incidence of reported varicella cases (2015–2022), outpatient and emergency department visits (2019–2024), hospitalizations (2015–2024), in-hospital deaths with a recorded varicella diagnosis (2018–2020), institutional outbreaks, and first-dose vaccination coverage (2018–2024). Results: From 2015 to 2022, reported incidence declined by 84% in males and 83% in females, after increasing through 2019 and declining markedly during the COVID-19 pandemic. Children aged 1–9 years accounted for the largest proportion of reported cases. Among 354 hospitalizations, adults aged 20–44 years accounted for 30.5%. Hospitalizations among children aged ≤4 years decreased by approximately 56% between 2015–2018 and 2021–2024, while annual hospitalizations among adults aged 20–44 years increased from 7 in 2015 to 21 in 2024, representing a 200% increase over the study period. Three deaths occurred during hospitalizations with a varicella diagnosis, all among adults, and one institutional outbreak was identified. First-dose vaccination coverage averaged approximately 94% during 2018–2022 and remained high thereafter. Conclusions: Reported varicella incidence declined substantially during the study period, but circulation and healthcare burden persisted, with hospitalizations increasingly concentrated among adults. Because our analysis lacks a pre-vaccination comparator, these trends cannot be causally attributed to vaccination based on our data alone. The findings support maintaining high first-dose coverage and strengthening surveillance. Further information on individual vaccination history and population susceptibility is needed to evaluate the potential contribution of a two-dose vaccination strategy in Costa Rica.

Background: Costa Rica introduced universal one-dose varicella vaccination in 2007. Although the disease burden subsequently declined, varicella cases and hospitalizations continue to be reported. We characterized varicella epidemiology and healthcare burden in Costa Rica using the most recent nationally available data. Methods: We conducted a nationwide retrospective descriptive study using aggregated surveillance and ad-ministrative data from the Ministry of Health and the Costa Rican Social Security Fund. Outcomes included notified incidence (2015–2022), outpatient and emergency department visits (2019–2024), hospitalizations (2015–2024), in-hospital deaths associated with varicella (2018–2020), reported institutional outbreaks, and first-dose vaccination coverage (2018–2024). Results: Between 2015 and 2022, incidence declined by 84% in males and 83% in females, although it increased until 2019 and declined markedly during the COVID-19 pandemic. Infants and children aged 1–9 years accounted for the largest proportion of reported cases. Among 354 hospitalizations, adults aged 20–44 years accounted for 30.5%. Comparing 2015–2018 with 2021–2024, hospitalizations declined by approximately 56% among chil-dren aged < 4 years and increased by approximately 200% among adults aged 20–44 years. Three varicel-la-associated in-hospital deaths, all in adults, and one institutional outbreak were identified. First-dose coverage averaged approximately 92% during 2018–2022 and exceeded 95% in 2023–2024. Conclusions: Despite substantial reductions in reported incidence, varicella circulation and healthcare burden persist, with hospitalizations increasingly concentrated among adults. These findings support sustaining high first-dose coverage, strengthening surveillance, and evaluating the potential contribution of a two-dose vac-cination strategy.

Introduction Zero-dose children (ZDC) are defined as those that have never been reached by routine immunization services. In Latin America, almost 2.7 million infants younger than 1 year of age, have incomplete vaccination schedules, and vaccine preventable diseases such as measles or polio have increase worldwide. ZDC are reported to reside in high risk and fragile settings, including remote-rural areas, urban slums, and conflict-affected areas. Identifying the problem and settings in each country is mandatory to propose possible solutions to the immunization coverage situation. Areas covered In November 2023, a group of experts of the Latin America Society of Pediatric Infectious Diseases (SLIPE) analyzed the global and regional reality of ZDC, and present in this document an updated reality of the Latin American region and the weight of the possible interventions to overcome this problem. Expert commentary Communication is a key element to improve vaccination coverage, as it is quality and use of vaccination data. Campaigns that deliver targeted and effective messages to communities and families, provide education about vaccination, avoid missed vaccination opportunities, and coordinate efforts across different sectors and communities, among other strategies, could improve the current immunization situation.

Influenza behavior depends on several characteristics: the agent itself, the host response, and environmental changes that determine seasonality, presentation, disease severity, lethality, and intensity of contagion. Vulnerable populations, such as the elderly, people with underlying diseases, and incomplete vaccination status, can influence disease presentation and epidemiology. These information changes are necessary for existing surveillance systems. Special surveillance of human and animal diseases is necessary, considering recent outbreaks and epidemic waves of viral diseases such as avian influenza. This study analyzed the impact of the COVID-19 pandemic on influenza vaccination coverage in Mexico and Central America. We used existing data and information in the countries and what was reported to WHO and UNICEF on administrative coverage of influenza vaccination reported by the countries, and the PAHO surveillance databases for influenza and other respiratory viruses. Influenza vaccine application varies in Central American countries and Mexico. Vaccination schedules have been adapted following WHO and PAHO recommendations, and considering the epidemiological, organizational conditions and financial realities of each country. Surveillance systems must be prepared for a possible “tridemic” in humans involving influenza, SARS-CoV-2 and respiratory syncytial virus (RSV). Influenza-associated disease was considerably affected during the COVID-19 pandemic. Given the preventive measures implemented, cases were unusually low during 2021-22, but cases increased sharply in 2022-23 caused by influenza A and influenza A H1N1 pdm09, with some isolated cases of influenza B.

Introduction Zero-dose children (ZDC) are defined as those that have never been reached by routine immunization services. In Latin America, almost 2.7 million infants younger than 1 year of age, have incomplete vaccination schedules, and vaccine preventable diseases such as measles or polio have increase worldwide. ZDC are reported to reside in high risk and fragile settings, including remote-rural areas, urban slums, and conflict-affected areas. Identifying the problem and settings in each country is mandatory to propose possible solutions to the immunization coverage situation. Areas covered In November 2023, a group of experts of the Latin America Society of Pediatric Infectious Diseases (SLIPE) analyzed the global and regional reality of ZDC, and present in this document an updated reality of the Latin American region and the weight of the possible interventions to overcome this problem. Expert commentary Communication is a key element to improve vaccination coverage, as it is quality and use of vaccination data. Campaigns that deliver targeted and effective messages to communities and families, provide education about vaccination, avoid missed vaccination opportunities, and coordinate efforts across different sectors and communities, among other strategies, could improve the current immunization situation.

Objective To identify risk factors for severe disease in children hospitalised for SARS-CoV-2 infection. Design Multicentre retrospective cohort study. Setting 18 hospitals in Canada, Iran and Costa Rica from 1 February 2020 to 31 May 2021. Patients ChildrenMain outcome measure Severity on the WHO COVID-19 Clinical Progression Scale was used for ordinal logistic regression analyses. Results We identified 403 hospitalisations. Median age was 3.78 years (IQR 0.53–10.77). At least one comorbidity was present in 46.4% (187/403) and multiple comorbidities in 18.6% (75/403). Eighty-one children (20.1%) met WHO criteria for PCR-positive MIS-C. Progression to WHO clinical scale score ≥6 occurred in 25.3% (102/403). In multivariable ordinal logistic regression analyses adjusted for age, chest imaging findings, laboratory-confirmed bacterial and/or viral coinfection, and MIS-C diagnosis, presence of a single (adjusted OR (aOR) 1.90, 95% CI 1.13 to 3.20) or multiple chronic comorbidities (aOR 2.12, 95% CI 1.19 to 3.79), obesity (aOR 3.42, 95% CI 1.76 to 6.66) and chromosomal disorders (aOR 4.47, 95% CI 1.25 to 16.01) were independent risk factors for severity. Age was not an independent risk factor, but different age-specific comorbidities were associated with more severe disease in age-stratified adjusted analyses: cardiac (aOR 2.90, 95% CI 1.11 to 7.56) and non-asthma pulmonary disorders (aOR 3.07, 95% CI 1.26 to 7.49) in childrenConclusion We identified risk factors for disease severity among children hospitalised for PCR-positive SARS-CoV-2 infection. Comorbidities predisposing children to more severe disease may vary by age. These findings can potentially guide vaccination programmes and treatment approaches in children.

Age is the most important determinant of COVID-19 severity. Infectious disease severity by age is typically J-shaped, with infants and the elderly carrying a high burden of disease. We report on the comparative disease severity between infants and older children in a multicenter retrospective cohort study of children 0 to 17 years old admitted for acute COVID-19 from February 2020 through May 2021 in 17 pediatric hospitals. We compare clinical and laboratory characteristics and estimate the association between age group and disease severity using ordinal logistic regression. We found that infants comprised one-third of cases, but were admitted for a shorter period (median 3 days IQR 2–5 versus 4 days IQR 2–7), had a lower likelihood to have an increased C-reactive protein, and had half the odds of older children of having severe or critical disease (OR 0.50 (95% confidence interval 0.32–0.78)).    Conclusion: When compared to older children, there appeared to be a lower threshold to admit infants but their length of stay was shorter and they had lower odds than older children of progressing to severe or critical disease. What is Known: • A small proportion of children infected with SARS-CoV-2 require hospitalization for acute COVID-19 with a subgroup needing specialized intensive care to treat more severe disease. • For most infectious diseases including viral respiratory tract infections, disease severity by age is J-shaped, with infants having more severe disease compared to older children. What is New: • One-third of admitted children for acute COVID-19 during the first 14 months of the pandemic were infants. • Infants had half the odds of older children of having severe or critical disease.

Understanding antibiotic profiles and their resistance patterns can improve hospital quality care and optimize clinical outcomes. This paper characterizes the use of meropenem in the National Children’s Hospital of Caja Costarricense del Seguro Social (CCSS) in Costa Rica, and its role in antibiotic stewardship. This is a retrospective observational study from hospitalized patients under 13 years of age that received meropenem as part of their treatment. Patients were identified through medical and pharmacy records. Data was summarized using frequencies and percentages for categorical variables, means and standard deviations for normally distributed continuous variables, and medians with interquartile ranges (IQR) for non-normally distributed continuous variables. A total of 181 of the 309 selected patients met inclusion criteria. Median age was 21 months (IQR: 4.0-79.0). Mean length of stay was 31 days (16.0-58.0). The most frequent diagnosis was septic shock (29%). 87% of patients received at least one antibiotic prior to receiving meropenem; 71% of patients received a second antibiotic simultaneously with meropenem. In 113 (62%) cases, meropenem was prescribed as empirical therapy. The most frequent isolate was extended-spectrum ß-lactamase Escherichia coli (24%). 74% of patients who received meropenem as targeted therapy had a favorable outcome. Meropenem can be used as monotherapy for complicated, multi-drug resistant, gram negative, bacterial infections, due to its susceptibility profile, convenient dosing schedule, and minimum adverse effects. However, it should be restricted to cases where no other drug is available in order to safeguard its value.

Background A cohort study was conducted to describe and compare the characteristics of SARS-CoV-2 infection in hospitalized children in three countries. Methods This was a retrospective cohort of consecutive children admitted to 15 hospitals (13 in Canada and one each in Iran and Costa Rica) up to November 16, 2020. Cases were included if they had SARS-CoV-2 infection or multi-system inflammatory syndrome in children (MIS-C) with molecular detection of SARS-CoV-2 or positive SARS-CoV-2 serology. Results Of 211 included cases (Canada N=95; Costa Rica N=84; Iran N=32), 103 (49%) had a presumptive diagnosis of COVID-19 or MIS-C at admission while 108 (51%) were admitted with other diagnoses. Twenty-one (10%) of 211 met criteria for MIS-C. Eighty-seven (41%) had comorbidities. Children admitted in Canada were older than those admitted to non-Canadian sites (median 4.1 versus 2.2 years; pConclusions Approximately half of hospitalized children with confirmed SARS-CoV-2 infection or MIS-C were admitted with other suspected diagnoses. Disease severity was higher at non-Canadian sites. Neonates, children with comorbidities and those with chest radiographs compatible with COVID-19 were at increased risk for severe or critical COVID-19. Main points Approximately half of hospitalized children with laboratory confirmed MIS-C or SARS-CoV-2 infection were admitted with another primary diagnoses. The severity of disease was higher in the middle income countries (Costa Rica and Iran) than in Canada.