Under-diagnosis of SARS-CoV-2 infections among children aged 0–15 years, a nationwide seroprevalence study, Israel, January 2020 to March 2021

Until recently, children and adolescents were not eligible for COVID-19 vaccination. They may have been a considerable source of SARS-CoV-2 spread. We evaluated SARS-CoV-2 IgG antibody seroprevalence in Israeli children aged 0–15 years from January 2020 to March 2021. Seropositivity was 1.8–5.5 times higher than COVID-19 incidence rates based on PCR testing. We found that SARS-CoV-2 infection among children is more prevalent than previously thought and emphasise the importance of seroprevalence studies to accurately estimate exposure.

Knowledge, Attitude, and Prevention Practice on Dengue and Dengue Seroprevalence in a Dengue Hotspot in Sabah, East Malaysia

Background: Dengue, a major global public health concern, is growing more prevalent. Extensive measures have been undertaken to prevent and control dengue transmission in Malaysia including understanding and modification of human behaviour. This study was designed to assist in planning an effective health intervention for dengue by measuring residents’ knowledge, attitudes, and practice (KAP) in hotspot areas of Sabah, East Malaysia. Methods: A community-based and cross-sectional study was conducted at dengue hotspot area in Sabah involving 463 residents (aged 18 years and above). Information on the socio-demographic characteristics of the residents and their KAP towards dengue was collected using a structured pre-validated questionnaire developed by the researchers. In addition, residents were invited to participate in a dengue seroprevalence study using dengue Immunoglobulin M (IgM) and Immunoglobulin G (IgG) ELISA kit. Results: Most of the residents correctly identified common signs and symptoms of dengue such as fever (84.4%), chills (70.7%), and nausea or vomiting (56.0%). Nearly half of the residents (51.3%) had good knowledge, 66.0% had a positive attitude, and 63.7% had a positive practice for dengue prevention and control, respectively. The dengue seroprevalence study included 200 of the 463 residents; IgG and IgM seropositivity was 74.1% (n = 63) and 7.1% (n = 6) respectively. Based on logistic regression analysis, local and migrants differs considerably in terms of their knowledge and attitude toward dengue prevention and control, while gender and level of education were predictive of practice level (p<0.05) among all sociodemographic variables examined. Knowledge was correlated with attitude (p<0.0001) and practice (p< 0.0014). Discussion: To combat dengue epidemics in the hotspot area of Sabah, a proactive and behavioural changes among residents, are required. To effectively prevent and manage dengue transmission, a collaborative effort of government sectors, private sectors, housing residential committees, and community residents is essential.

Disparities in SARS-CoV-2 exposure: evidence from a citywide seroprevalence study in Holyoke, Massachusetts, USA

Background: Seroprevalence studies are important tools to estimate the prevalence of prior or recent SARS-CoV-2 infections, identifying hotspots and high-risk groups and informing public health responses to the COVID-19 pandemic. We conducted a city-level seroprevalence study in Holyoke, Massachusetts, USA to estimate the seroprevalence of SARS-CoV-2 antibodies and risk factors for seropositivity. Methods: We invited inhabitants of 2,000 randomly sampled addresses between November 5 and December 31, 2020. Participants completed questionnaires measuring sociodemographic and health characteristics, and COVID-19 exposure history, and provided dried blood spots for measurement of SARS-CoV-2 IgG and IgM antibodies. We calculate total and subgroup seroprevalence estimates based on presence of IgG antibodies using a Bayesian procedure that incorporates uncertainty in antibody test sensitivity and specificity. We account for clustering by household and weighting based on demographic characteristics to ensure estimates represented the citys population. Findings: We enrolled 280 households including 472 individuals. 328 underwent antibody testing. The citywide seroprevalence estimate of SARS-CoV-2 IgG was 13.1% (95%CI 6.9-22.3) compared to 9.8% based on publicly reported case counts. Seroprevalence was 16.1% (95%CI 6.2-31.8) among individuals identifying as Hispanic compared to 9.4% (95%CI 4.6-16.4) among those identifying as non-Hispanic white. Seroprevalence was higher among Spanish speaking households (21.9%; 95% CI 8.3-43.9) compared to English speaking households (10.2%; 95% CI 5.2-18.0) and among individuals living in high vulnerability areas (14.4%; 95% CI 7.1-25.5) compared to low vulnerability areas (8.2%; 95% CI 3.1-16.9). Interpretation: The measured SARS-CoV-2 seroprevalence of IgG antibodies in Holyoke was only 13.1% during the second surge of SARS-CoV-2 in this region, far from accepted thresholds for herd immunity. Already vulnerable communities were at highest risk of prior infection. Implementation of local serosurveys in tandem with proactive public health interventions that address disparities in SARS-CoV-2 exposure are crucial to ensure at-risk communities have appropriate educational materials and access to vaccines, testing, and timely treatment.

A Seroprevalence Study of Anti-SARS-CoV-2 Antibodies in Patients with Inflammatory Bowel Disease during the Second Wave of the COVID-19 Pandemic in Italy

Background and Objectives: Studies have shown a lower prevalence of anti-SARS-CoV-2 antibodies in patients with inflammatory bowel disease (IBD), including amongst those receiving biological therapy. Aims were to determine the seroprevalence of anti-SARS-CoV-2 antibodies in IBD patients and to assess any association between seropositivity and IBD characteristics. Materials and Methods: Serum from adult IBD patients was prospectively collected between December 2020 and January 2021 and analyzed for anti-SARS-CoV-2 antibodies. Information about IBD characteristics and SARS-CoV-2 exposure risk factors was collected and analyzed. Serum from non-IBD healthcare workers formed the control group. Results: 311 IBD patients on biologics and 75 on mesalazine were enrolled. Ulcerative colitis (UC) extension (p < 0.001), Crohn’s disease (CD) phenotype (p = 0.009) and use of concomitant corticosteroids (p < 0.001) were significantly different between the two IBD groups. Overall seroprevalence among IBD patients was 10.4%. The control group showed a prevalence of 13.0%, not significantly different to that of IBD patients (p = 0.145). Only a close contact with SARS-CoV-2 positive individuals and the use of non-FFP2 masks were independently associated with a higher likelihood of seropositivity amongst IBD patients. Conclusion: In IBD patients, the prevalence of anti-SARS-CoV-2 antibodies is not determined by their ongoing treatment. Disease-related characteristics are not associated with a greater risk of antibody seropositivity.