Seroprevalence of antibodies to SARS-CoV-2 among blood donors in the early month of the pandemic in Saudi Arabia

Background: Serologic testing provides better understanding of SARS-CoV-2 prevalence and its transmission. This study was an investigation of the prevalence of antibodies to SARS-CoV-2 among blood donors in Saudi Arabia. Objective: To estimate the seroprevalence of anti-SARS-CoV-2 antibodies among blood donors in Saudi Arabia during the early phase of the COVID-19 pandemic. Methods: Serology results and epidemiological data were analyzed for 837 adult blood donors, with no confirmed SARS-CoV-2 infection, in Saudi Arabia from 20th to 25th May 2020. Seroprevalence was determined using electrochemical immunoassay to detect anti-SARS-CoV-2 antibodies. Results: The overall seroprevalence of anti-SARS-CoV-2 antibodies was 1.4% (12/837). Non-citizens had higher seroprevalence compared with citizens (OR 13.6, p = 0.001). Secondary education was significantly associated with higher seroprevalence compared with higher education (OR 6.8, p = 0.005). The data showed that the highest seroprevalence was in Makkah (8.1%). Uisng Makkah seroprevalence as the reference, the seroprevalence in other areas was: Madinah 4.1% (OR 0.48, 95% CI 0.12-1.94), Jeddah 2.3% (OR 0.27, 95% CI 0.31-2.25), and Qassim 2.9 % (OR 0.34, 95% CI 0.04-2.89) and these were not statistically different from seroprevalence in the Makkah region. Conclusions: At the early months of the COVID-19 pandemic in Saudi Arabia, the seroprevalence of antibodies to SARS-CoV-2 among blood donors was low, but was higher among non-citizens. These findings may indicate that non-citizens and less educated individuals may be less attentive to preventive measures. Monitoring seroprevalence trends over time require repeated sampling

Household Air Pollution Causes Dose-dependent Inflammation and Altered Phagocytosis in Human Macrophages

Background Three billion people are exposed to household air pollution from biomass fuel use. Exposure is associated with higher incidence of pneumonia, and possibly tuberculosis. Understanding mechanisms underlying these defects would improve preventive strategies. Methods We used human alveolar macrophages obtained from healthy Malawian adults exposed naturally to household air pollution, and compared with human monocyte-derived macrophages exposed in vitro to respirable-sized particulates. Cellular inflammatory response was assessed by: IL-6 and IL-8 production in response to particulate challenge; phagocytosis of fluorescent-labelled beads and intraphagosomal oxidative burst capacity; ingestion and killing of Streptococcus pneumoniae and Mycobacterium tuberculosis measured by microscopy and quantitative culture. Particulate ingestion was quantified by digital image analysis. Results We were able to reproduce the carbon loading of naturally exposed alveolar macrophages by in vitro exposure of monocyte derived macrophages. Fine carbon black induced IL-8 release from monocyte derived and alveolar macrophages (p<0.05), with similar magnitude responses (log10 increases of 0.93 [SEM 0.2] vs 0.74 [SEM 0.19] respectively). Phagocytosis of pneumococci and mycobacteria was impaired with higher particulate loading. High particulate loading corresponded with a lower oxidative burst capacity (p=0.0015). There was no overall effect on killing of M. tuberculosis. Conclusion Alveolar macrophage function is altered by particulate loading. Our macrophage model is comparable morphologically to the in vivo uptake of particulates. Wood smoke exposed cells demonstrate reduced phagocytosis but unaffected mycobacterial killing, suggesting defects related to chronic wood smoke inhalation limited to specific innate immune functions

SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study

Background: Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods: The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18-49, 50-69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results: NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. Conclusion: As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population