SARS-CoV-2 seroprevalence among children in Greece during Omicron variant period

The Omicron variant is associated with increased transmissibility, but evidence about the impact of Omicron in seropositivity of children is limited. This study aims to evaluate SARS-CoV-2 seroprevalence in children during the different variants' subperiods. A prospective multicenter seroprevalence study was conducted in 7 University public hospitals in Greece from November 2021 to August 2022 (3 subperiods: November 2021-February 2022, March 2022-May 2022, June 2022-August 2022). Children from different age groups, admitted to the hospital or examined in outpatient clinics for reasons other than COVID-19 were enrolled. Neutralizing antibodies (Nabs), anti-Spike (anti-S) and anti-nucleocapsid (anti-N) SARS-CoV-2 IgG in serum were evaluated. A total of 2127 children (males:57,2%; median age:4,8years) were enrolled. Anti-N IgG seropositivity increased from 17,8% in the first sub-period to 40,7% in the second sub-period and then decreased in the third sub-period (36,7%). Anti-S IgG seropositivity appeared to have an increasing trend over the study period, starting from 34,8% and reaching 80,7%. Children aged 1-4 years old have significantly higher anti-N IgG titers compared to children aged 0-1 years old (p < 0,001). Infants have significantly lower anti-S IgG titers compared to all other age groups (p < 0,001). Immunocompromised children and infants have the lowest seropositivity for NAbs.Conclusions During the Omicron period, seropositivity significantly increased, as a result of higher transmissibility. Neonates and infants have lower antibody titers compared to other age groups, while young children aged 1-4 years old present higher antibody titers, suggesting that this age group may mount a higher antibody response. Continuous surveillance seroprevalence studies are needed in children, in order to identify the true extent of SARS-CoV-2 and guide the planning of adequate public health measures.

Multisystem inflammatory syndrome in children (MIS-C): A nationwide collaborative study in the Greek population

Multisystem inflammatory syndrome in children (MIS-C) is a rare but severe hyperinflammatory condition that may occur following SARS-CoV-2 infection. This retrospective, descriptive study of children hospitalized with multisystem inflammatory syndrome in children (MIS-C) in 12 tertiary care centers from 3/11/2020 to 12/31/2021. Demographics, clinical and laboratory characteristics, treatment and outcomes are described. Among 145 patients (95 males, median age 8.2 years) included, 123 met the WHO criteria for MIS-C, while 112 (77%) had serological evidence of SARS-CoV-2 infection. Fever was present in 99%, gastrointestinal symptoms in 77%, mucocutaneous involvement in 68% and respiratory symptoms in 28%. Fifty-five patients (38%) developed myocarditis, 29 (20%) pericarditis and 19 (13%) coronary aneurysms. Among the above cases 11/55 (20%), 1/29 (3.4%) and 5/19 (26.3%), respectively, cardiac complications had not fully resolved at discharge. Underlying comorbidities were reported in 18%. Median CRP value was 155 mg/l, ferritin 535 ng/ml, PCT 1.6 ng/ml and WBC 14.2 × 109/mm3. Most patients had elevated troponin (41.3%) and/or NT-pro-BNP (49.6%). Intravenous immunoglobulin plus corticosteroids were used in 117/145 (80.6%), monotherapy with IVIG alone in 13/145 (8.9%) and with corticosteroids alone in 2/145 (1.3%). Anti-IL1 treatment was added in 15 patients (10.3%). Thirty-three patients (23%) were admitted to the PICU, 14% developed shock and 1 required ECMO. Mortality rate was 0.68%. The incidence of MIS-C was estimated at 0.69/1000 SARS-CoV-2 infections. Patients who presented with shock had higher levels of NT-pro-BNP compared to those who did not (p < 0.001). Acute kidney injury and/or myocarditis were associated with higher risk of developing shock.

CONCLUSION

MIS-C is a novel, infrequent but serious disease entity. Cardiac manifestations included myocarditis and pericarditis, which resolved in most patients before discharge. Timely initiation of immunomodulatory therapy was shown to be effective. NT-pro-BNP levels may provide a better prediction and monitoring of the disease course. Further research is required to elucidate the pathogenesis, risk factors and optimal management, and long-term outcomes of this clinical entity.

WHAT IS KNOWN

• MIS-C is an infrequent but serious disease entity. • Patients with MIS-C present with multi-organ dysfunction, primarily involving the gastrointestinal and cardiovascular systems.

WHAT IS NEW

• NT-pro-BNP levels may provide a better prediction and monitoring of the disease course. • Acute kidney injury and/or myocarditis were associated with higher risk of developing shock.

Seroprevalence of anti-SARS-CoV-2 antibodies among children and their parents in Greece

School closures were enforced as measures to restrain the COVID-19 pandemic, based on the assumption that young children may play a key role in SARS-CoV-2 spread. This study aims to determine the prevalence of SARS-CoV-2 IgG antibodies in children and corresponding parents, in order to improve surveillance and estimate the prevalence of asymptomatic or subclinical COVID-19 cases. A prospective multicenter study was conducted between March and June 2021 in Greece. Children admitted to the hospital or examined in outpatient clinics for reasons other than COVID-19 and their parents were tested for anti-Spike SARS-CoV-2 IgG in serum. A questionnaire about clinical and demographic data was completed. The study included 823 participants: 427 children and 396 corresponding parents. The overall seroprevalence was 16.4% in parents and 13.8% in children. Among families with ≥ 1 seropositive child or parent, the combination of a seropositive parent and a corresponding seronegative child was 29.6%, a seronegative parent and a corresponding seropositive child was 24.7%, and a seropositive child with a corresponding seropositive parent was 45.7%. Age, level of education, and school or work attendance were not significantly associated with increased seropositivity. On the contrary, ethnic minority of Roma, close contact with known COVID-19 case, previous symptoms consistent with COVID-19, and mass gatherings were risk factors for seropositivity.

CONCLUSION

The spread of SARS-CoV-2 during a period of lockdown in Greece was low in children and comparable to adults most likely due to intrafamilial transmission. Accordingly, it is unlikely that children have boosted virus transmission.

WHAT IS KNOWN

• In the earliest months of the pandemic, it was demonstrated that children had significantly lower seroprevalence rates than the older age groups, due to the fact that children had decreased exposure to the virus, because of early public health interventions, such as school and day care closure. • Later, further studies reported that children have similar incidence rate of SARS-CoV-2 infection compared to adults in households and community settings.

WHAT IS NEW

• In this seroprevalence study, the spread of SARS-CoV-2 infection during a period of lockdown in Greece with the predominance of the Alpha-variant was particularly low in children and comparable to adults, most likely due to intrafamilial transmission. • These study findings will be useful for decisions regarding non-pharmaceutical interventions during the pandemic, and especially, to guide in designing and implementing appropriate containment measures for schools and social gatherings.

Cross-sectional prevalence of SARS-CoV-2 antibodies in healthcare workers in paediatric facilities in eight countries

Background

Healthcare workers (HCWs) have been disproportionately affected by coronavirus disease 2019 (COVID-19), which may be driven, in part, by nosocomial exposure. If HCW exposure is predominantly nosocomial, HCWs in paediatric facilities, where few patients are admitted with COVID-19, may lack antibodies to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and be at increased risk during the current resurgence.

Aim

To compare the seroprevalence of SARS-CoV-2 amongst HCWs in paediatric facilities in seven European countries and South Africa (N=8).

Methods

All categories of paediatric HCWs were invited to participate in the study, irrespective of previous symptoms. A single blood sample was taken and data about previous symptoms were documented. Serum was shipped to a central laboratory in London where SARS-CoV-2 immunoglobulin G was measured.

Findings

In total, 4114 HCWs were recruited between 1^st May and mid-July 2020. The range of seroprevalence was 0–16.93%. The highest seroprevalence was found in London (16.93%), followed by Cape Town, South Africa (10.36%). There were no positive HCWs in the Austrian, Estonian and Latvian cohorts; 2/300 [0.66%, 95% confidence interval (CI) 0.18–2.4] HCWs tested positive in Lithuania; 1/124 (0.81%, 95% CI 0.14–4.3) HCWs tested positive in Romania; and 1/76 (1.3%, 95% CI 0.23–7.0) HCWs tested positive in Greece.

Conclusion

Overall seroprevalence amongst paediatric HCWs is similar to their national populations and linked to the national COVID-19 burden. Staff working in paediatric facilities in low-burden countries have very low seroprevalence rates and thus are likely to be susceptible to COVID-19. Their susceptibility to infection may affect their ability to provide care in the face of increasing cases of COVID-19, and this highlights the need for appropriate preventative strategies in paediatric healthcare settings.

Time trends in pediatric hospitalizations for hepatitis A in Greece (1999-2013): Assessment of the impact of universal infant immunization in 2008

Hepatitis A vaccine was introduced in the Greek National Immunization Program in 2008. To estimate possible impact of the universal vaccination implementation, time trends of hospitalizations for hepatitis A at the Infectious Diseases Unit of a Tertiary Pediatric Hospital in Athens during 1999-2013 were analyzed. Hepatitis A hospitalizations were recorded from the discharge database and were expressed as frequencies and rate of annual departmental hospitalizations. Time series analysis (ARIMA) was used to explore trends and the impact of the vaccination. Moreover, changes in patient age, population group distribution and the duration of hospitalization were also examined. Hepatitis A hospitalizations rate significantly decreased between pre-vaccination (1999-2008) and post-vaccination (2009-2013) era from 50.5 to 20.8/1000 hospitalizations (p = 0.005). A 3-year periodicity and a trend of reduction on hepatitis A hospitalizations rates across years were noted. Roma children had significant higher rates of hepatitis A hospitalization, followed by immigrant children. Importantly, possibly due to preceding vaccine availability with considerable uptake in private market and unvaccinated group/pockets of children (Roma), overall vaccination effect was less apparent when compared to data from other countries that implemented universal vaccination. No significant change in patient age, population group distribution, or duration of hospitalization was observed. High risk groups such as Roma children should be targeted for vaccination to reduce future outbreaks.

Long-lasting hyporesponsivenss induced by the 23-valent pneumococcal polysaccharide vaccine (PPV23) in asplenic patients with β-thalassemia major

We have previously shown that multiple vaccinations with 23-valent pneumococcal polysaccharide vaccine (PPV23s) resulted in attenuated antibody responses to subsequent 7-valent conjugate vaccine (PCV7) in asplenic adults with β-thalassemia major (Orthopoulos et al. Vaccine 2009; 27:350). However, there is evidence that PPV23-induced immune hyporesponsiveness could be overcome with time (Papadatou et al. Clin Infect Dis 2014; 59:862). In the current study we investigate the duration of hyporesponsiveness in the same cohort seven years after the original study vaccinations. Patients received one dose of 13-valent conjugate vaccine (PCV13) and antibody levels were measured before and one month after vaccination. Antibodies increased significantly after vaccination with PCV13, but were lower than post-PCV7 seven years earlier. Lower pre-vaccination antibody levels were associated with more robust response to PCV13. Our findings suggest that PPV23 should be used cautiously in asplenic adults vaccinated with multiple PPV23s in the past. Measurement of anti-pneumococcal antibodies before and after vaccination could be used to optimise timing of vaccinations and certify vaccine immunogenicity in such individuals.

Cognitive and psychosocial development of HIV pediatric patients receiving highly active anti-retroviral therapy: a case-control study

BACKGROUND

The psychosocial development of pediatric HIV patients has not been extensively evaluated. The study objectives were to evaluate whether emotional and social functions are differentially associated with HIV-related complications.

METHODS

A matched case-control study design was conducted. The case group (n = 20) consisted of vertically infected children with HIV (aged 3-18 years) receiving HAART in Greece. Each case was matched with two randomly selected healthy controls from a school-based population. CNS imaging and clinical findings were used to identify patients with HIV-related neuroimaging abnormalities. The Wechsler Intelligence Scale III and Griffiths Mental Abilities Scales were applied to assess cognitive abilities. The age specific Strengths and Difficulties Questionnaire was used to evaluate emotional adjustment and social skills. The Fisher's exact test, student's t-test, and Wilcoxon rank sum test were used to compare categorical, continuous, and ordinal scores, respectively, of the above scales between groups.

RESULTS

HIV patients without neuroimaging abnormalities did not differ from patients with neuroimaging abnormalities with respect to either age at HAART initiation (p = 0.306) or months of HAART treatment (p = 0.964). While HIV patients without neuroimaging abnormalities had similar cognitive development with their healthy peers, patients with neuroimaging abnormalities had lower mean General (p = 0.027) and Practical (p = 0.042) Intelligence Quotient scores. HIV patients without neuroimaging abnormalities had an increased likelihood of both Abnormal Emotional Symptoms (p = 0.047) and Hyperactivity scores (p = 0.0009). In contrast, HIV patients with neuroimaging abnormalities had an increased likelihood of presenting with Abnormal Peer Problems (p = 0.033).

CONCLUSIONS

HIV patients without neuroimaging abnormalities are more likely to experience maladjustment with respect to their emotional and activity spheres, while HIV patients with neuroimaging abnormalities are more likely to present with compromised social skills. Due to the limited sample size and age distribution of the study population, further studies should investigate the psychosocial development of pediatric HIV patients following the disclosure of their condition.

Long-term immunity to measles, mumps and rubella after MMR vaccination among children with bone marrow transplants

Measles, mumps and rubella (MMR) vaccine-induced long-term immunity was studied in 30 children with bone marrow transplants (BMT). Immunity at baseline for MMR was 13.3, 33.3 and 66.6%, respectively. MMR vaccination failed to induce adequate and persistent responses to measles and mumps; seropositivity at 1 and 12 months for measles was 26.6 and 23.3% and for mumps 46.6 and 36.6%, respectively. In contrast, 27 of 30 children with a BMT were immune to rubella 1 month after immunization and retained protective antibody levels at 12 months. The MMR-induced anamnestic responses to rubella among all responders were associated with the production of high avidity antibodies. We conclude that a single dose of MMR given at 2 years after BMT induces suboptimal and short-lived immune responses to measles and mumps; a second dose should be recommended for paediatric BMT recipients.

Kinetics of antibody concentration and avidity for the assessment of immune response to pneumococcal vaccine among children with bone marrow transplants

The kinetics of the immune response to the 23-valent pneumococcal polysaccharide vaccine (PPV) were studied in 38 children who received bone marrow transplants (BMTs). Anti-pneumococcal antibody concentrations increased 1 and 3 months after vaccination for all 5 serotypes tested, but, in 21 children, the vaccine was not adequately immunogenic. Children vaccinated <18 months after receiving a BMT had a 4.2-fold increased odds of poor response (P=. 06). Antibody concentrations returned close to baseline levels 9 months after vaccination. Avidity declined significantly as early as 1 month after vaccination and remained low thereafter. Antibody concentration responses to PPV were superior among 9 healthy control children (P=.001); 37 of 38 children with a BMT elicited adequate, persistent immune responses to Haemophilus influenzae conjugate vaccine. Immune responses to PPV in children with a BMT are suboptimal, short lived, and associated with declining avidity. The different kinetics of antibody concentration and avidity indicate that both markers should be used for evaluating pneumococcal vaccines in this high-risk population.

Persistence of antibody responses to Haemophilus influenzae type b polysaccharide conjugate vaccine in children with vertically acquired human immunodeficiency virus infection

BACKGROUND

Recurrent bacterial sepsis is common in pediatric HIV infection and immunization against Haemophilus influenzae type b (Hib) is recommended. Long term persistence of anti-Hib antibody and the need for, or timing of, a booster dose has not been adequately studied.

METHODS

Immunogenicity during a 12-month period following immunization with Hib-tetanus conjugate vaccine (ACT-HIB; Merieux) was evaluated in 48 vertically HIV-infected children and 36 uninfected children, born to HIV-positive mothers. A titer of anti-Hib polysaccharide antibody of > or = 0.15 microgram/ml was considered to indicate short term and > or = 1 microgram/ml long term protection.

RESULTS

At 1 month postvaccination 36 (100%) uninfected and 42 (88%) HIV-infected children achieved titers of > or = 1 microgram/ml. However, by 1 year titers had dropped below this value in 18 (43%) infected compared with only 4 (11%) uninfected children (chi square, 9.7; P = 0.002). Although the rate of fall of antibody titer was greater in uninfected than in infected children, this was no longer the case after adjustment for the 1-month postimmunization titer. The rate of antibody titer decline was not significantly related to HIV disease status or to either the age-related CD4 count at the time of immunization or the change in age-adjusted CD4 count during the 12 months after immunization.

CONCLUSIONS

Not only was the initial antibody response to Hib conjugate vaccine decreased in children with HIV infection and AIDS but also 1 year later only 57% of the initial responders had persisting titers above the level associated with long term protection. The need for reimmunization of children with HIV infection against Hib requires further evaluation.

Hypogammaglobulinaemia secondary to reflux oesophagitis

A 7 year old girl referred for investigation of hypogammaglobulinaemia had hypoalbuminaemia and severe necrotising oesophagitis on oesophagogastroduodenoscopy. Nissen fundoplication resolved all clinical and laboratory abnormalities, but she remains under surveillance because of histological findings of Barrett's oesophagus. Erosive reflux oesophagitis can present with minimal localising symptoms, and hypogammaglobulinaemia and hypoalbuminaemia, presumably from protein loss.