What was behind the first recognition and characterization of autochthonous SARS-CoV-2 transmission in Italy: who opened Pandora’s Box in Europe? (preprint)

An Italian male with no link to China SARS-CoV-2 epidemic presented at Emergency Room with severe respiratory impairment. The RT-PCR on 20th February, 2020, nasopharyngeal swab revealed SARS-CoV-2 infection, confirmed with viral culture and sequencing. This was the first identified autochthonous SARS-CoV-2 transmission in Italy, that unveiled global pathogen diffusion.

Geographic reconstruction of the SARS-CoV-2 outbreak in Lombardy (Italy) during the early phase (preprint)

The circulation of SARS-CoV-2 in Italy has been dominated by two large clusters of outbreaks in Northern part of the peninsula, source of alarming and prolonged infections in Lombardy region, in Codogno and Bergamo areas especially. The aim of the study was to expand understanding on the circulation of SARS-CoV-2 in the affected Lombardy areas. To this purpose, twenty full length genomes were collected from patients addressing to several Lombard hospitals from February 20th to April 4th, 2020. The obtained genome assemblies, available on the GISAD database and performed at the Referral Center for COVID-19 diagnosis, identified 2 main monophyletic clades, containing 9 and 52 isolates, respectively. The molecular clock analysis estimated a clusters divergence approximately one month before the first patient identification, supporting the hypothesis that different SARS-CoV-2 strains spread all over the world at different time, but their presence became evident only in late February along with Italian epidemic emergence. Therefore, the epidemiological reconstruction carried out by this work highlights multiple inputs of the virus into its initial circulation in Lombardy Region. However, a phylogenetic reconstruction robustness will be improved when other genomic sequences will be available, in order to guarantee a complete epidemiological surveillance.

In-Utero Mother-to-Child SARS-CoV-2 Transmission: Viral Detection and Fetal Immune Response (preprint)

Pregnancy is known to increase the risk of severe illnesses in response to viral infections. Therefore, the impact of SARS-CoV-2 infection during gestational ages might be detrimental and the potential vertical transmission should be thoroughly studied.Herein, we investigated whether SARS-CoV-2 vertical transmission is possible and, in case, whether this results in a fetal involvement. Additionally, we analyzed the role of the antibody and the inflammatory responses in placenta and plasma from SARS-CoV-2-positive pregnant women and fetuses.31 SARS-CoV-2 pregnant women were enrolled. Real-time PCR was performed to detect the virus on maternal and newborns’ nasopharyngeal swabs, vaginal swabs, maternal and umbilical cord plasma, placenta and umbilical cord biopsies, amniotic fluids and milk. Maternal and umbilical cord plasma, and milk were tested for specific anti-SARS-CoV-2 antibodies. RNA expression quantification of genes involved in the inflammatory response was performed on four selected placentas. On maternal and umbilical cord plasma of the same subjects, secreted cytokines/chemokines were quantified.SARS-CoV-2 is found in at-term placentae and in the umbilical cord blood, in the vaginal mucosa of pregnant women and in milk. Furthermore, we report the presence of specific anti-SARS-CoV-2 IgM and IgG antibodies in the umbilical cord blood of pregnant women, as well as in milk specimens. Finally, a specific inflammatory response is triggered by SARS-CoV-2 infection in pregnant women at both systemic and placental level, and in umbilical cord blood plasma.Our data strongly support the hypothesis that in-utero vertical transmission is possible in SARS-CoV-2 positive pregnant women. This is essential for defining proper obstetric management of COVID-19 pregnant women, or putative indications for mode and timing of delivery.

IN-UTERO MOTHER-TO-CHILD SARS-CoV-2 TRANSMISSION: viral detection and fetal immune response (preprint)

Pregnancy is known to increase the risk of severe illnesses in response to viral infections. Therefore, the impact of SARS-CoV-2 infection during gestational ages might be detrimental and the potential vertical transmission should be thoroughly studied. Herein, we investigated whether SARS-CoV-2 vertical transmission is possible and, in case, whether this results in a fetal involvement. Additionally, we analyzed the role of the antibody and the inflammatory responses in placenta and plasma from SARS-CoV-2-positive pregnant women and fetuses. 31 SARS-CoV-2 pregnant women were enrolled. Real-time PCR was performed to detect the virus on maternal and newborns nasopharyngeal swabs, vaginal swabs, maternal and umbilical cord plasma, placenta and umbilical cord biopsies, amniotic fluids and milk. Maternal and umbilical cord plasma, and milk were tested for specific anti-SARS-CoV-2 antibodies. RNA expression quantification of genes involved in the inflammatory response was performed on four selected placentas. On maternal and umbilical cord plasma of the same subjects, secreted cytokines/chemokines were quantified. SARS-CoV-2 is found in at-term placentae and in the umbilical cord blood, in the vaginal mucosa of pregnant women and in milk. Furthermore, we report the presence of specific anti-SARS-CoV-2 IgM and IgG antibodies in the umbilical cord blood of pregnant women, as well as in milk specimens. Finally, a specific inflammatory response is triggered by SARS-CoV-2 infection in pregnant women at both systemic and placental level, and in umbilical cord blood plasma. Our data strongly support the hypothesis that in-utero vertical transmission is possible in SARS-CoV-2 positive pregnant women. This is essential for defining proper obstetric management of COVID-19 pregnant women, or putative indications for mode and timing of delivery.

Presence and vitality of SARS-CoV-2 virus in wastewaters and rivers (preprint)

Wastewater-based epidemiology has been proposed to monitor the diffusion and trend of SARS-CoV-2 pandemic. In the present study, raw and treated samples from three wastewater treatment plants, and two river samples characterized the Milano Metropolitan Area, Italy, were surveyed for SARS-CoV-2 RNA positivity to real time PCR and infectiveness. Moreover, whole genome sequencing and phylogenetic analysis of isolated strains was performed. Raw wastewater samples resulted positive to PCR amplification, while treated water samples were always negative (four and two samples, respectively, sampled in two dates). Moreover, the rate of positivity in raw wastewater samples decreased after eight days, in congruence with the epidemiological trend estimated for the interested provinces. Virus infectiveness was always not significant, indicating the effectiveness of wastewater treatments, or the natural decay of viral vitality, which implied the absence of significant risk of infection from wastewaters. Samples from receiving rivers (two sites, sampled in the same dates as wastewaters) showed in some cases a positivity to PCR amplification, probably due to non-treated discharges, or the combined sewage overflows. Nevertheless, also for rivers vitality was negligible, indicating the absence of sanitary risks. Phylogenetic analysis of genome indicated that the isolated virus belongs to the most spread strain present in Europe and similar to another strain found in Lombardy.