Small girl receiving vaccine in a medical clinic.

January 17, 2024

COVID: Children and Other Vulnerable Populations

  • Outcomes of SARS-CoV-2 and Seasonal Viruses Among Children Hospitalized in Brazil
    This population-based, retrospective cohort study included children and adolescents hospitalized with severe acute respiratory infection (SARI) from February 2020 to February 2023 in Brazil. The investigators looked at a total of 235,829 patients that had available results of the viral tests, with SARS-CoV-2 predominance. According to the competing-risk survival analysis, they estimated probability of a fatal outcome at 30 days of hospitalization according to the different viral infections. Fatal outcome for in-hospital mortality was SARS-CoV-2 – 6.5%, coinfection – 3.4%, adenovirus – 2.9%, influenza – 2.3%, other viruses – 2.1%, and respiratory syncytial virus – 1.8%.
  • COVID-19 Vaccine Effectiveness Among Adolescents
    In this study, nationwide register-based 1-to-1 matched cohort analyses were conducted in Denmark, Finland, Norway, and Sweden between May 28, 2021, and April 30, 2023, to estimate VE for primary COVID-19 vaccine (two-dose) schedules among adolescents aged 12 to 17 years. Cumulative incidences of COVID-19–related hospitalization (primary outcome) and laboratory-confirmed SARS-CoV-2 infection (secondary outcome) were compared for vaccinated and unvaccinated at six months of follow-up. The study included 526,966 primary schedule vaccinated adolescents. VE against COVID-19–related hospitalization was 72.6% at six months of follow-up compared with unvaccinated. Estimates were comparable when restricting to a period of Omicron predominance and extending follow-up to 12 months.
  • Vaccine Effectiveness Against Long COVID in Children
    The adjusted vaccine effectiveness within 12 months was 35% against probable Long COVID in a retrospective cohort study used data from 17 health systems that looked at 1,037,936 children.
  • Socioemotional Development of Infants and Toddlers During the COVID-19 Pandemic
    The background of this study as the authors point out is that the COVID-19 pandemic and its related social distancing have negatively affected children and families. Caregiver stress increased, which can negatively affect infant development and health. Children’s screen time increased, which is associated with poorer language, problem-solving, and social development. Daycare and preschool closures, along with social distancing, decreased peer interactions for young children. While studies suggest young children’s socio-emotional development was affected during the pandemic, assessments specifically designed to evaluate socio-emotional development, changes in screening results over time, or referrals to early intervention (EI) have not been examined. Here, they used specific validated early childhood development assessments and looked at 60,171 families and found that the pandemic contributed to delays in young children’s socio-emotional development, particularly during the first year of life.

COVID: The Late Phase/PASC/Long COVID

  • Long COVID Manifests with T cell Dysregulation, Inflammation and an Uncoordinated Adaptive Immune Response to SARS-CoV-2
    This paper really requires some time but is complicated and requires a solid background in immunology to fully understand. The authors explain that they used ‘omic” assays and serology to deeply characterize the global and SARS-CoV-2-specific immunity in the blood of individuals with clear LC and non-LC clinical trajectories, eight months postinfection. They found that LC individuals exhibited systemic inflammation and immune dysregulation evidenced by global differences in T cell subset distribution implying ongoing immune responses, as well as by sex-specific perturbations in cytolytic subsets. LC individuals displayed increased frequencies of CD4+ T cells poised to migrate to inflamed tissues and exhausted SARS-CoV-2-specific CD8+ T cells, higher levels of SARS-CoV-2 antibodies and a mis-coordination between their SARS-CoV-2-specific T and B cell responses. Their analysis suggested an improper crosstalk between the cellular and humoral adaptive immunity in LC, which can lead to immune dysregulation, inflammation and clinical symptoms associated with this debilitating condition. Every figure is complicated with multiple panels and there are supplemental figures as well.
  • The effectiveness of COVID-19 vaccines to prevent long COVID symptoms: staggered cohort study of data from the UK, Spain, and Estonia
    Investigators conducted a staggered cohort study using primary care records from the UK (Clinical Practice Research Datalink [CPRD] GOLD and AURUM), Catalonia, Spain (Information System for Research in Primary Care [SIDIAP]), and national health insurance claims from Estonia (CORIVA database).  They found that compared with unvaccinated people, overall HRs for Long COVID symptoms in people vaccinated with a first dose of any COVID-19 vaccine ranged from 0.49-0.71 and consistently was associated with a reduced risk of persistent symptoms after a COVID infection. The other way to interpret this is that Vaccine efficacy (VE) against long COVID ranged from 29% to 52%. This is consistent with several other studies, and the benefit may be more pronounced in women than in men.
  • Impact of COVID-19 vaccination on symptoms and immune phenotypes in vaccine-naïve individuals with Long COVID
    (Preprint, posted on MedRxiv.) In this prospective study, authors evaluated changes in symptoms and immune responses after COVID-19 vaccination in 16 vaccine-naïve individuals with Long COVID. Surveys were administered before vaccination and then at two, six, and 12 weeks after receiving the first vaccine dose of the primary series. Simultaneously, SARS-CoV-2-reactive TCR enrichment, SARS-CoV-2-specific antibody responses, antibody responses to other viral and self-antigens, and circulating cytokines were quantified before vaccination and at six and 12 weeks after vaccination. Self-report at 12 weeks post-vaccination indicated 10 out of 16 participants had improved health, three had no change, one had worse health, and two reported marginal changes. Significant elevation in SARS-CoV-2-specific TCRs and Spike protein-specific IgG were observed six and 12 weeks after vaccination. No changes in reactivities were observed against herpes viruses and self-antigens. Within this dataset, higher baseline sIL-6R was associated with symptom improvement, and the two top features associated with non-improvement were high IFN-β and CNTF, among soluble analytes.

Situation Dashboards


World Health Organization (WHO)

Novel Coronavirus (COVID-19) Situation from World Health Organization (WHO)

Johns Hopkins University (JHU)

Coronavirus COVID-19 Global Cases by the Center for Systems Science and Engineering (CSSE) at JHU

COVID-19 in US and Canada

1Point3Acres Real-Time Coronavirus (COVID-19) Updates in US and Canada with Credible Sources

Genomic Epidemiology COVID-19

Genomic Epidemiology of (COVID-19) Maintained by the Nextstrain team, enabled by data from GISAID.

Sources for COVID-19 Information


World Health Organization (WHO)


Centers for Disease Control, US


International Society for Infectious Diseases


This Week in Virology (TWIV)

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