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1.
SSRN;
Preprint in English | SSRN | ID: ppcovidwho-326281

ABSTRACT

Background: The omicron variant has spread globally at unprecedented speed due to a combination of epidemiological and virological factors that still need to be fully unraveled. Although boosting of immunity in vaccinated populations has proven to increase the antibody recognition for this variant, we still ignore the impact that this intervention has on protection from infection and disease. Methods: Relying on a live virus neutralization assay and a commercial chemiluminescence immunoassay targeting antibodies against the receptor binding domain (RBD) of the parental Spike protein, we tested the efficacy of homologous and heterologous booster vaccinations in inducing antibodies against SARS-CoV-2 parental, delta, beta and omicron variants by history of SARS-CoV-2 infection and age of population. Booster vaccination was performed with the BNT126b2 vaccine, while individuals who underwent heterologous booster vaccination were primed with the ChAdOx1 nCov-19 vaccine. Moreover, we studied the impact that prior immunity has on vaccination, in mildly infected individuals who received 2-3 doses of the BNT1262b vaccine at different times after infection. Children previously infected with delta were evaluated 3·5 months after infection. To translate neutralization data into estimates of protection, we relied on published predictive models and inferred variant-specific thresholds of protection for both assays and assessed the accuracy of the commercial assay at identifying highly protected individuals. Findings: We confirm that boosting significantly restores the ability of antibodies to recognize omicron and other variants, and that the homologous protocol with the BNT126b2 vaccine achieves higher and more broadly reactive neutralizing antibody titers, than those observed among individuals who crossed-over vaccines. On the other hand, mild prior infection with the parental virus and subsequent homologous vaccination with BNT126b2 induces high antibody levels, but with moderate breadth of response, while children aged 5-11 show negligible neutralizing antibodies against the omicron variant few months from infection. Neutralizing and binding antibodies correlate across all variants and allow the identification of variant-specific anti-RBD thresholds for 90% protection efficacy. Interpretation: Boosting with the BNT126b2 vaccine is an immediate and effective measure to increase the protection against omicron, in naïve, as well as in previously infected individuals. Identification through serological commercial assays of thresholds of protection against the omicron and delta variants is a crucial step towards large-scale serosurveys to finely assess infection risk both at population and individual level.

2.
Nat Commun ; 12(1): 6610, 2021 11 16.
Article in English | MEDLINE | ID: covidwho-1521737

ABSTRACT

COVID-19 typically manifests as a respiratory illness, but several clinical reports have described gastrointestinal symptoms. This is particularly true in children in whom gastrointestinal symptoms are frequent and viral shedding outlasts viral clearance from the respiratory system. These observations raise the question of whether the virus can replicate within the stomach. Here we generate gastric organoids from fetal, pediatric, and adult biopsies as in vitro models of SARS-CoV-2 infection. To facilitate infection, we induce reverse polarity in the gastric organoids. We find that the pediatric and late fetal gastric organoids are susceptible to infection with SARS-CoV-2, while viral replication is significantly lower in undifferentiated organoids of early fetal and adult origin. We demonstrate that adult gastric organoids are more susceptible to infection following differentiation. We perform transcriptomic analysis to reveal a moderate innate antiviral response and a lack of differentially expressed genes belonging to the interferon family. Collectively, we show that the virus can efficiently infect the gastric epithelium, suggesting that the stomach might have an active role in fecal-oral SARS-CoV-2 transmission.


Subject(s)
COVID-19/pathology , Intestinal Mucosa/virology , Organoids/virology , SARS-CoV-2/physiology , Stomach/virology , Virus Replication/physiology , Aborted Fetus , Aged , Animals , COVID-19/virology , Cell Line , Child , Child, Preschool , Chlorocebus aethiops , Humans , Infant , Intestinal Mucosa/pathology , Middle Aged , Organoids/pathology , SARS-CoV-2/isolation & purification , Stomach/pathology
3.
Eur J Epidemiol ; 36(7): 685-707, 2021 Jul.
Article in English | MEDLINE | ID: covidwho-1326830

ABSTRACT

Coronavirus disease (COVID-19) is a respiratory disease affecting many people and able to be transmitted through direct and perhaps indirect contact. Direct contact transmission, mediated by aerosols or droplets, is widely demonstrated, whereas indirect transmission is only supported by collateral evidence such as virus persistence on inanimate surfaces and data from other similar viruses. The present systematic review aims to estimate SARS-CoV-2 prevalence on inanimate surfaces, identifying risk levels according to surface characteristics. Data were obtained from studies in published papers collected from two databases (PubMed and Embase) with the last search on 1 September 2020. Included studies had to be papers in English, had to deal with coronavirus and had to consider inanimate surfaces in real settings. Studies were coded according to our assessment of the risk that the investigated surfaces could be contaminated by SARS-CoV-2. A meta-analysis and a metaregression were carried out to quantify virus RNA prevalence and to identify important factors driving differences among studies. Thirty-nine out of forty retrieved paper reported studies carried out in healthcare settings on the prevalence of virus RNA, five studies carry out also analyses through cell culture and six tested the viability of isolated viruses. Overall prevalences of SARS-CoV-2 RNA on high-, medium- and low-risk surfaces were 0.22 (CI95 [0.152-0.296]), 0.04 (CI95 [0.007-0.090]), and 0.00 (CI95 [0.00-0.019]), respectively. The duration surfaces were exposed to virus sources (patients) was the main factor explaining differences in prevalence.


Subject(s)
COVID-19 , Equipment Contamination , Fomites/virology , RNA, Viral/isolation & purification , SARS-CoV-2/isolation & purification , Humans , Microbial Viability , Prevalence
4.
Pediatrics ; 148(3)2021 09.
Article in English | MEDLINE | ID: covidwho-1280670

ABSTRACT

BACKGROUND: Recent evidence suggests that neutralizing antibodies (nAbs) to severe acute respiratory syndrome coronavirus 2 may persist over time; however, knowledge regarding pediatric subjects is limited. METHODS: A single-center, prospective observational study was conducted on 57 family clusters of coronavirus disease 2019, including children of neonatal and pediatric age attending the University Hospital of Padua (Italy). For each patient, blood samples were collected for both the quantification of nAbs through a plaque reduction neutralizing test and the detection of antinucleocapsid-spike protein immunoglobulin G and/or immunoglobulin M. RESULTS: We analyzed 283 blood samples collected from 152 confirmed coronavirus disease 2019 cases (82 parents and 70 children or older siblings of median age of 8 years, interquartile range: 4-13), presenting asymptomatic or with mildly symptomatic disease. Despite the decrease of immunoglobulin G over time, nAbs were found to persist up to 7 to 8 months in children, whereas adults recorded a modest declining trend. Interestingly, children aged <6 years, and, in particular, those aged <3 years, developed higher long-lasting levels of nAbs compared with older siblings and/or adults. CONCLUSIONS: Mild and asymptomatic severe acute respiratory syndrome coronavirus 2 infections in family clusters elicited higher nAbs among children.


Subject(s)
Antibodies, Neutralizing/blood , Antibodies, Viral/blood , COVID-19/blood , SARS-CoV-2/immunology , Adolescent , Adult , Age Factors , COVID-19/immunology , COVID-19 Serological Testing , Child , Child, Preschool , Cluster Analysis , Data Collection , Humans , Immunoglobulin G/blood , Immunoglobulin M/blood , Infant , Infant, Newborn , Italy , Neutralization Tests , Prospective Studies , Symptom Assessment , Time Factors
5.
Sci Total Environ ; 778: 146191, 2021 Jul 15.
Article in English | MEDLINE | ID: covidwho-1117651

ABSTRACT

The current pandemic caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has led people to implement preventive measures, including surface disinfection and use of alcohol-based hand gel, in order to avoid viral transmission via fomites. However, the role of surface transmission is still debated. The present systematic review aims to summarize all the evidence on surface survival of coronaviruses infecting humans. The analysis of 18 studies showed the longest coronavirus survival time is 28 days at room temperature (RT) on different surfaces: polymer banknotes, vinyl, steel, glass, and paper banknotes. Concerning SARS-CoV-2 human infection from contaminated surfaces, dangerous viral load on surfaces for up to 21 days was determined on polymer banknotes, steel, glass and paper banknotes. For viruses other than SARS-CoV-2, the longest period of survival was 14 days, recorded on glass. Environmental conditions can affect virus survival, and indeed, low temperatures and low humidity support prolonged survival of viruses on contaminated surfaces independently of surface type. Furthermore, it has been shown that exposure to sunlight significantly reduces the risk of surface transmission. Although studies are increasingly investigating the topic of coronavirus survival, it is difficult to compare them, given the methodology differences. For this reason, it is advisable to define a reference working protocol for virus survival trials, but, as an immediate measure, there is also a need for further investigations of coronavirus survival on surfaces.


Subject(s)
COVID-19 , Fomites , Humans , Humidity , Pandemics , SARS-CoV-2
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