Breakthrough SARS-CoV-2 infections in double and triple vaccinated adults and single dose vaccine effectiveness among children in Autumn 2021 in England: REACT-1 study.

Background: Prevalence of SARS-CoV-2 infection with Delta variant was increasing in England in late summer 2021 among children aged 5 to 17 years, and adults who had received two vaccine doses. In September 2021, a third (booster) dose was offered to vaccinated adults aged 50 years and over, vulnerable adults and healthcare/care-home workers, and a single vaccine dose already offered to 16 and 17 year-olds was extended to children aged 12 to 15 years. Methods: SARS-CoV-2 community prevalence in England was available from self-administered throat and nose swabs using reverse transcriptase polymerase chain reaction (RT-PCR) in round 13 (24 June to 12 July 2021, N = 98,233), round 14 (9 to 27 September 2021, N = 100,527) and round 15 (19 October to 5 November 2021, N = 100,112) from the REACT-1 study randomised community surveys. Linking to National Health Service (NHS) vaccination data for consenting participants, we estimated vaccine effectiveness in children aged 12 to 17 years and compared swab-positivity rates in adults who received a third dose with those who received two doses. Findings: Weighted SARS-CoV-2 prevalence was 1.57% (1.48%, 1.66%) in round 15 compared with 0.83% (0.76%, 0.89%) in round 14, and the previously observed link between infections and hospitalisations and deaths had weakened. Vaccine effectiveness against infection in children aged 12 to 17 years was estimated (round 15) at 64.0% (50.9%, 70.6%) and 67.7% (53.8%, 77.5%) for symptomatic infections. Adults who received a third vaccine dose were less likely to test positive compared to those who received two doses, with adjusted OR of 0.36 (0.25, 0.53). Interpretation: Vaccination of children aged 12 to 17 years and third (booster) doses in adults were effective at reducing infection risk. High rates of vaccination, including booster doses, are a key part of the strategy to reduce infection rates in the community. Funding: Department of Health and Social Care, England.

Prevaccination Seroprevalence of COVID-19 Immunoglobulin G Antibodies in Health-care Personnel and General Population after First Pandemic Wave in a Himalayan Region in North India

Introduction: COVID-19 has been declared as Public Health Emergency of International Concern with extreme risk of sustained global spread. The pandemic is likely to evolve in successive waves until herd immunity threshold (HIT) is achieved. Asymptomatic carriers and contacts are likely to elude case reporting through conventional algorithm of case finding, testing, contact tracing, and outbreak surveillance, thereby leading to underestimation of disease burden. Widespread community-level transmission of COVID-19 renders higher risk to health-care personnel due to higher propensity and duration of multiple exposures compared to general population. Methods: This is a cross-sectional clinicoepidemiological outcome surveillance study on prevaccination seroprevalence of COVID-19 immunoglobulin G (IgG) antibodies against S1 receptor binding domain in health-care personnel and general population. Results: Seroprevalence of COVID-19 IgG in 570 health-care personnel was 224/570 (39.3%), without any skew based on age or gender. 75% were exposed in the hospital while 21.2% were exposed during travel and 3.1% through high-risk contact outside the hospital. Out of 33 COVID-19 positives, 88% underwent hospital isolation including one ICU admission and 12 home isolation. Seroprevalence of COVID-19 IgG in 400 individuals from general population samples was 138/400 (34.5%). Conclusion: Prevaccination seroprevalence of COVID-19 IgG antibodies after the first pandemic wave revealed no significant difference among health-care personnel and general population reflecting upon a possibility of consecutive pandemic waves until community attainment of HIT. Seroepidemiology can be a robust tool essential to ascertain exposure, immune response, immunity status, and predict susceptibility in population cohorts.

Wastewater-based SARS-CoV-2 environmental monitoring for Piedmont, Italy.

The experience gained over the last hundred years clearly indicates that two groups of viruses represent the main risk for the development of highly transmissible epidemics and pandemics in the human species: influenza viruses and coronaviruses (CoV). Although the search for viruses with pandemic potential in the environment may have an important predictive and monitoring role, it is still based on empirical methodologies, mostly resulting from the clinic and not fully validated for environmental matrices. As far as the SARS-CoV-2 pandemic, currently underway, is concerned, environmental monitoring activities aiming at checking the presence of SARS-CoV-2 in wastewater can be extremely useful to predict and check the diffusion of the disease. For this reason, the present study aims at evaluating the SARS-CoV-2 diffusion by means of a wastewater-based environmental monitoring developed in Piedmont, N-W Italy, during the second and third pandemic waves. Wastewater sampling strategies, sampling points sample pre-treatments and analytical methods, data processing and standardization, have been developed and discussed to give representative and reliable results. The following outcomes has been highlighted by the present study: i) a strong correlation between SARS-CoV-2 concentration in untreated wastewater and epidemic evolution in the considered areas can be observed as well as a predictive potential that could provide decision-makers with indications to implement effective policies, to mitigate the effects of the ongoing pandemic and to prepare response plans for future pandemics that could certainly arise in the decades to come; ii) moreover, the data at disposal from our monitoring campaign (almost 500 samples analysed in 11 months) confirm that SARS-CoV-2 concentrations in wastewater are strongly variable and site-specific across the region: the highest SARS-CoV-2 concentration values have been found in sewer networks serving the most populated areas of the region; iii) normalization of viral concentrations in wastewater through Pepper Mild Mottle Virus (a specific faecal marker) has been carried out and commented; iv) the study highlights the potential of wastewater treatment plants to degrade the genetic material referable to SARS-CoV-2 as well. In conclusion, the preliminary data reported in the present paper, although they need to be complemented by further studies considering also other geographical regions, are very promising.

The prevalence of SARS-CoV-2 antibodies in triage-negative patients and staff of a fertility setting from lockdown release throughout 2020.

STUDY QUESTION: What is the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in triage-negative patients undergoing ART and fertility care providers after lockdown release and throughout 2020? SUMMARY ANSWER: Out of the triage-negative patients whose blood samples were assessed for SARS-CoV-2 antibodies over 6 months, 5.2% yielded positive results with a significantly higher rate in health care workers (HCWs) and a significant month-by-month increase in those with evidence of antibodies. WHAT IS KNOWN ALREADY: Patients of reproductive age are more prone to asymptomatic or minimal forms of coronavirus disease 2019 (COVID-19) as compared to older age groups, and the identification of those with active infection and those already exposed (and probably immunized) is important for safety and cost-effective use of testing resources in the fertility setting. Data on the prevalence of SARS-CoV-2 in ART patients are limited and encompass short time frames; current rates are unknown. There is also no consensus on the optimal way of screening triage-negative ART patients in moderate/high-risk areas. STUDY DESIGN SIZE DURATION: A prospective longitudinal unicentric study on triage negative ART patients (n = 516) and clinical staff (n = 30) was carried out. We analyzed 705 serological tests for SARS-CoV-2 sampled between 17 May 2020 (the first working day after lockdown release) up to 1 December 2020, to assess the positivity rates for SARS-CoV-2 antibodies. PARTICIPANTS/MATERIALS SETTING METHODS: We collected data on the serological status for IgM and IgG antibodies against SARS-CoV-2 in 516 triage-negative men (n = 123) and women (n = 393) undergoing ART at a private fertility center and 30 HCWs that were at work during the study period. Antibodies were detected with a capture chemiluminescence assay (CLIA) targeting the highly Immunogenic S1 and S2 domains on the virus spike protein. We also analyzed the molecular test results of the cases exhibiting a positive serology. MAIN RESULTS AND THE ROLE OF CHANCE: The data showed that 5.2% of the triage-negative ART patients had a positive serological result for SARS-CoV-2, with an overall conversion rate of 2.1% for IgG and 4.6% for IgM. There was no significant difference in seroprevalence between sexes. The small cohort (n = 30) of HCWs had a markedly increased seroprevalence (12.9% for Ig M and 22.6% for IgG). The highest seropositivity in our cohort was recorded in November (16.2%). The IgM positivity rates revealed significant monthly increments, paralleling official prevalence rates based on nasopharyngeal swabs. No positive molecular tests were identified in cases exhibiting a solitary positive IgG result. We show that despite a 6-fold increase in the number of ART patients with a positive serology between May and December 2020, most of our patients remain unexposed to the virus. The study was undertaken in a high-risk area for COVID-19, with a 20-times increase in the active cases across the study period. LIMITATIONS REASONS FOR CAUTION: The geographical restriction, alongside the lack of running a second, differently-targeted immunoassay (orthogonal testing), could limit the generalizability and translation of our results to other fertility settings or other immunoassays. WIDER IMPLICATIONS OF THE FINDINGS: The low positivity rates for IgG against the SARS-CoV-2 spike protein seen at the end of 2020 imply that most of the fertility patients are still at risk for SARS-CoV-2 infection. Until mass vaccination and other measures effectively diminish the pandemic, risk mitigation strategies must be maintained in the fertility units in the foreseeable future. Patients with a solitary IgG+ status are most likely 'non-infectious' and can elude further testing without giving up the strict use of universal protective measures. With increasing seroprevalences owing to infection or vaccination, and with the consecutive increase in test performance, it is possible that serological screening of ART patients might be more cost-effective than PCR testing, especially for the many patients with repeat treatments/procedures in a time-frame of months. STUDY FUNDING/COMPETING INTERESTS: This research received no external funding. All authors declare having no conflict of interest with regard to this trial.

A phenomenological estimate of the true scale of CoViD-19 from primary data.

Estimation of the prevalence of undocumented SARS-CoV-2 infections is critical for understanding the overall impact of CoViD-19, and for implementing effective public policy intervention strategies. We discuss a simple yet effective approach to estimate the true number of people infected by SARS-CoV-2, using raw epidemiological data reported by official health institutions in the largest EU countries and the USA.

SARS-CoV-2 in Danish Mink Farms: Course of the Epidemic and a Descriptive Analysis of the Outbreaks in 2020.

SARS-CoV-2 infection is the cause of COVID-19 in humans. In April 2020, SARS-CoV-2 infection in farmed mink (Neovision vision) occurred in the Netherlands. The first outbreaks in Denmark were detected in June 2020 in three farms. A steep increase in the number of infected farms occurred from September and onwards. Here, we describe prevalence data collected from 215 infected mink farms to characterize spread and impact of disease in infected farms. In one third of the farms, no clinical signs were observed. In farms with clinical signs, decreased feed intake, increased mortality and respiratory symptoms were most frequently observed, during a limited time period (median of 11 days). In 65% and 69% of farms, virus and sero-conversion, respectively, were detected in 100% of sampled animals at the first sampling. SARS-CoV-2 was detected, at low levels, in air samples collected close to the mink, on mink fur, on flies, on the foot of a seagull, and in gutter water, but not in feed. Some dogs and cats from infected farms tested positive for the virus. Chickens, rabbits, and horses sampled on a few farms, and wildlife sampled in the vicinity of the infected farms did not test positive for SARS-CoV-2. Thus, mink are highly susceptible to infection by SARS-CoV-2, but routes of transmission between farms, other than by direct human contact, are unclear.