Estimating the cumulative incidence of SARS-CoV-2 infection and the infection fatality ratio in light of waning antibodies

The effects of vitamin D deficiency on mandibular bone structure: a retrospective radiological study

OBJECTIVE

The aim of the study was to evaluate the effects of vitamin D deficiency on the mandibular bone structure by fractal analysis and panoramic morphometric indices.

METHODS

Ninety participants were divided into three groups as 30 individuals with severe vitamin D deficiency, 30 individuals with vitamin D deficiency, and 30 individuals with vitamin D sufficiency. Fractal dimension analysis (FD), panoramic mandibular index (PMI), mandibular cortical index (MCI), and mandibular cortical thickness measurement (CTM) were evaluated on panoramic radiographs.

RESULTS

FD values of the patients with vitamin D deficiency were found to be statistically lower than the patients with vitamin D sufficiency (p < 0.05). FD value of supracortical area above the angulus mandible (FD2) in patients with severe vitamin D deficiency was significantly lower than FD values (p = 0.002). There was no statistically significant difference between the groups in the CTM (p > 0.05). PMI was significantly lower in patients with severe vitamin D deficiency (p < 0.001). There was a significant difference in MCI values between the groups (p < 0.05).

CONCLUSION

Vitamin D deficiency causes a decrease in bone mineral density in the mandible, and an increase in alveolar porosity. FD analysis and radiomorphometric indices in panoramic radiographs can be used to assess osteoporotic changes in patients with vitamin D deficiency.

Vitamin D deficiency: concern for rheumatoid arthritis and COVID-19?

Vitamin D is an immunomodulatory hormone with an established role in calcium and phosphate metabolism and skeletal mineralization. Evidence showing its immunological benefits by regulating essential components of the innate and adaptive immune system is prevalent. Vitamin D deficiency is reported worldwide and is thereby found to be associated with various immune-related diseases. Rheumatoid Arthritis and COVID-19 are two such diseases, sharing a similar hyperinflammatory response. Various studies have found an association of lower Vitamin D levels to be associated with both these diseases. However, contrasting data is also reported. We review here the available scientific data on risk factor association and supplementation benefits of Vitamin D in Rheumatoid Arthritis and COVID-19, intending to critically evaluate the literature.

Information About COVID-19 Testing on College Websites in the New York City Metropolitan Area

The continuing COVID-19 pandemic significantly impacted the Fall reopening plans among institutions of higher education (IHEs) in the United States (U.S.). While recommendations were made to conduct COVID-19 testing of students and staff, it is unclear as to what extent IHEs were able to engage in testing. IHEs also play a critical role in provision of accurate information related to COVID-19 to students and staff. The purpose of this cross-sectional study was to assess available information on COVID-19 testing on IHEs' websites in the New York City (NYC) metropolitan area. IHEs' websites were screened for the presence of content related to COVID-19 testing. Larger institutions (> 10,000 students) were more likely than smaller institutions (≤ 5000 students) to provide information on how to make an appointment for COVID-19 testing (χ2(2) = 8.1, P < 0.05), and information on free testing (χ2(2) = 7.0, P < 0.05). Of 150 IHEs included, 124 (82.7%) IHE's reported testing data to the campus community, with the majority providing this data biweekly (62.9%). A total of 116 IHEs recorded at least one positive COVID-19 case among their students or staff during the Fall semester. Smaller-sized institutions reported a significantly lower number of cases than medium- (P < 0.001) and large-sized (P = 0.003) institutions. Additional differences related to testing modalities and provision of information were observed according to schools' state jurisdictions. Although geographically close, IHEs in the NYC metropolitan area did not provide information on COVID-19 testing in a uniform and comprehensive fashion, which may further contribute to public confusion.

SARS-CoV-2 serology across scales: a framework for unbiased seroprevalence estimation incorporating antibody kinetics and epidemic recency

Serosurveys are a key resource for measuring SARS-CoV-2 cumulative incidence. A growing body of evidence suggests that asymptomatic and mild infections (together making up over 95% of all infections) are associated with lower antibody titers than severe infections. Antibody levels also peak a few weeks after infection and decay gradually. We developed a statistical approach to produce adjusted estimates of seroprevalence from raw serosurvey results that account for these sources of spectrum bias. We incorporate data on antibody responses on multiple assays from a post-infection longitudinal cohort, along with epidemic time series to account for the timing of a serosurvey relative to how recently individuals may have been infected. We applied this method to produce adjusted seroprevalence estimates from five large-scale SARS-CoV-2 serosurveys across different settings and study designs. We identify substantial differences between reported and adjusted estimates of over two-fold in the results of some surveys, and provide a tool for practitioners to generate adjusted estimates with pre-set or custom parameter values. While unprecedented efforts have been launched to generate SARS-CoV-2 seroprevalence estimates over this past year, interpretation of results from these studies requires properly accounting for both population-level epidemiologic context and individual-level immune dynamics.

Modelling COVID-19 outbreaks in USA with distinct testing, lockdown speed and fatigue rates

Each state in the USA exhibited a unique response to the COVID-19 outbreak, along with variable levels of testing, leading to different actual case burdens in the country. In this study, via per capita testing dependent ascertainment rates, along with case and death data, we fit a minimal epidemic model for each state. We estimate infection-level responsive lockdown/self-quarantine entry and exit rates (representing government and behavioural reaction), along with the true number of cases as of 31 May 2020. Ultimately, we provide error-corrected estimates for commonly used metrics such as infection fatality ratio and overall case ascertainment for all 55 states and territories considered, along with the USA in aggregate, in order to correlate outbreak severity with first wave intervention attributes and suggest potential management strategies for future outbreaks. We observe a theoretically predicted inverse proportionality relation between outbreak size and lockdown rate, with scale dependent on the underlying reproduction number and simulations suggesting a critical population quarantine 'half-life' of 30 days independent of other model parameters.

Nationwide seroprevalence of antibodies against SARS-CoV-2 in Israel

The first local spread of COVID-19 in Israel was detected in March 2020. Due to the diversity in clinical presentations of COVID-19, diagnosis by RT-PCR alone might miss patients with mild or no symptoms. Serology testing may better evaluate the actual magnitude of the spread of infection in the population. This is the first nationwide seroprevalence study conducted in Israel. It is one of the most widespread to be conducted thus far, and the largest per-country population size. The survey was conducted between June 28 and September 14, 2020 and included 54,357 patients who arrived at the Health Maintenance Organizations to undergo a blood test for any reason. A patient was considered seropositive after two consecutive positive results with two different kits (Abbott and DiaSorin).The overall seroprevalence was 3.8% (95%CI 3.7-4.0), males higher than females [4.9% (95%CI 4.6-5.2) vs. 3.1% (95%CI 2.9-3.3) respectively]. Adolescents had the highest prevalence [7.8% (95%CI 7.0-8.6)] compared to other age groups. Participants who had undergone RT-PCR testing had a tenfold higher risk to be seropositive. The prevalence-to-incidence ratio was 4.5-15.7. Serology testing is an important complimentary tool for assessing the actual magnitude of infection and thus essential for implementing policy measures to control the pandemic. A positive serology test result was recently accepted in Israel as being sufficient to define recovery, with possible far-reaching consequences, such as the deploying of employees to ensure the maintenance of a functional economy.

Reconciling estimates of global spread and infection fatality rates of COVID-19: An overview of systematic evaluations

BACKGROUND

Estimates of community spread and infection fatality rate (IFR) of COVID-19 have varied across studies. Efforts to synthesize the evidence reach seemingly discrepant conclusions.

METHODS

Systematic evaluations of seroprevalence studies that had no restrictions based on country and which estimated either total number of people infected and/or aggregate IFRs were identified. Information was extracted and compared on eligibility criteria, searches, amount of evidence included, corrections/adjustments of seroprevalence and death counts, quantitative syntheses and handling of heterogeneity, main estimates and global representativeness.

RESULTS

Six systematic evaluations were eligible. Each combined data from 10 to 338 studies (9-50 countries), because of different eligibility criteria. Two evaluations had some overt flaws in data, violations of stated eligibility criteria and biased eligibility criteria (eg excluding studies with few deaths) that consistently inflated IFR estimates. Perusal of quantitative synthesis methods also exhibited several challenges and biases. Global representativeness was low with 78%-100% of the evidence coming from Europe or the Americas; the two most problematic evaluations considered only one study from other continents. Allowing for these caveats, four evaluations largely agreed in their main final estimates for global spread of the pandemic and the other two evaluations would also agree after correcting overt flaws and biases.

CONCLUSIONS

All systematic evaluations of seroprevalence data converge that SARS-CoV-2 infection is widely spread globally. Acknowledging residual uncertainties, the available evidence suggests average global IFR of ~0.15% and ~1.5-2.0 billion infections by February 2021 with substantial differences in IFR and in infection spread across continents, countries and locations.

SARS-CoV-2 Infection Is Asymptomatic in Nearly Half of Adults with Robust Anti-Spike Protein Receptor-Binding Domain Antibody Response

Between June and November 2020, we assessed plasma antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid protein in 4996 participants (aged 18-82 years, 34.5% men) from the National and Kapodistrian University of Athens. The weighted overall prevalence was 1.6% and monthly prevalence correlated with viral RNA-confirmed SARS-CoV-2 infections in Greece, in the same period. Notably, 49% of seropositive cases reported no history of SARS-CoV-2 infection-related clinical symptoms and 33% were unsuspected of their previous infection. Additionally, levels of anti-SARS-CoV-2 antibodies against the spike-protein receptor-binding domain were similar between symptomatic and asymptomatic individuals, irrespective of age and gender. Using Food and Drug Administration Emergency Use Authorization-approved assays, these results support the need for such studies on pandemic evaluation and highlight the development of robust humoral immune responses even among asymptomatic individuals. The high percentage of unsuspected/asymptomatic active cases, which may contribute to community transmission for more days than that of cases who are aware and self-isolate, underscores the necessity of measures across the population for the efficient control of the pandemic.