key: cord-301484-y9l2hmqf
authors: MASSAROTTI, Claudia; ADRIANO, Marco; CAGNACCI, Angelo; GORLERO, Franco; GUSTAVINO, Claudio; VALLERINO, Gabriele; PAOLUCCI, Roberta; DI LUCA, Martina; ANSERINI, Paola; FERRAIOLO, Antonella
title: Asymptomatic SARS‐CoV‐2 infections in pregnant patients in an Italian city during complete lockdown
date: 2020-08-25
journal: J Med Virol
DOI: 10.1002/jmv.26458
sha: 
doc_id: 301484
cord_uid: y9l2hmqf

Data from both New York and London report a high prevalence of the asymptomatic SARS‐CoV‐2 infection in pregnant patients admitted for delivery, raising questions on the possible correlated dangers (i.e. contacts with healthcare workers; the possible creation of an intra‐hospital outbreak at birth; conflicting evidences on vertical transmission). For this study, results from SARS‐CoV‐2 screening via nasopharyngeal swab from maternity wards of the four hospitals of Genoa, Italy were collected during a month of complete lockdown, from April 1 to April 30, 2020. Out of 333 tested women, only nine were symptomatic. Only one symptomatic patient (0.3%) and six asymptomatic ones (1.8%) tested positive. Out of the six positive asymptomatic patients, five were from the most disadvantaged neighbourhood of the city (assessed by postal code). In conclusion, even if Italy was badly affected by COVID19 in the studied month, the reported prevalence of SARS‐CoV‐2 infections in asymptomatic pregnant patients at term was lower than the ones reported in literature. This article is protected by copyright. All rights reserved.

Early detection and isolation of asymptomatic SARS-CoV-2 positive patients is a crucial public safety action [1] , but a screening of the entire population is difficult to be This article is protected by copyright. All rights reserved.

organized and limited by test shortage. However, experiences of universal screenings in selected population were reported, among them pregnant patients admitted for delivery. The incidence of positive SARS-CoV-2 nasopharyngeal swabs in asymptomatic pregnant women were 13.5 and 6.2% in two reported screened cohort in New York and London [2, 3] .

Genoa is an Italian metropolitan city with 852.009 inhabitants, situated in Liguria, directly neighboring Lombardy, the most affected Italian region. The first COVID19 case in Genoa was reported on March 1, 2020. Italy imposed complete lockdown to the entire population since mid-March. The first COVID19 case in a symptomatic pregnant patient was diagnosed on March 13, 2020, followed by other 10 symptomatic cases in pregnancy during the same month. As a consequence, since April 1, 2020 a universal screening with RT-PCR on nasopharyngeal swabs was implemented in all maternity wards of the city hospitals (San Martino Hospital, G. Gaslini Hospital, Galliera Hospital, Villa Scassi -ASL3 Hospital).

Results from SARS-CoV-2 screening in all maternity wards were collected for this study from April 1, 2020 to April 30, 2020. Since the implementation of the universal screening, all pregnant women admitted for delivery were tested for SARS-CoV-2.

Women were initially triaged based on symptoms (fever and/or cough or other respiratory symptoms), contacts with positive patients and travel history. They were asked also for their demographic data, current working situation and observance of lockdown measures. All patients included signed a written informed consent for the use of their anonymized data for clinical research. All nasopharyngeal swabs, collected by a nurse or a midwife, were then centralized in two laboratories. Total RNA was extracted from the swabs using QIAamp viral RNA kit (Qiagen) according to the manufacturer's procedure, the RNA was retrotranscripted and amplified using SuperScript III Platinum One-Step qRT-PCR Kit and a specific assay using a Mastercycler RealPlex2S system (Eppendorf, Hamburg, Germany). The screening was performed at two levels, the first level examined the presence of gene E (Envelope) using the following primers: 313241, 313242, 313243 (TIB Molbiol s.r.l., Genoa); the second level examined the presence of gene RdRp (RNA Polymerasi RNA dependent) using the following primers:

Discussion COVID-19 transmission through asymptomatic carriers was described in literature during the early months of the pandemic [4, 5] and immediately raised great concern for the difficulties in identifying and isolating asymptomatic positive carriers. The experiences of universal screenings of pregnant people admitted to the hospital for delivery have great relevance for more than one reason. First of all, even if vertical transmission from an asymptomatic carrier was never described [6, 7] , these infections are still particularly dangerous, because of the numerous contacts with healthcare workers and the possible creation of an intra-hospital outbreak at birth. Awareness of the entity of the phenomenon is therefore an essential public health measure.

Moreover, while pregnant women could never be entirely representative of the general population, especially because of the hypothesized protective role of estrogens [8] , they are a subgroup in which such analysis is more feasible than in the entire population.

Our percentage of asymptomatic infected pregnant patients is considerably lower than previously reported, despite being in a region with high prevalence of the disease (+3508 new cases in April in Genoa) [9] . In our opinion it could be the direct effect of the lockdown measures, which were implemented in all Italy by national law more than two weeks before the start of our universal screening. Indeed, lockdown and social distancing have been proved to be among the most efficacious measure for infection containment [10] .

The existence of paid antenatal maternity leave for the vast majority of Italian population may have played a role too, but it is not possible to infer direct causation from this data. However, it is interesting to underline how none of the screened pregnant patients reported to have continued to work near term during COVID19 pandemic and they observed an almost complete lockdown. On note, the few cases reported were among the most disadvantaged population, in neighborhoods where it is more likely to live in smaller houses, with a higher number of cohabitants.

Our results represent a snapshot of a month in a severely hit area and underline once again the relevance of public health measures like social distancing, mask wearing and ultimately lockdown in the containment of the pandemic, reporting small numbers of

Racing Towards the Development of Diagnostics for a Novel Coronavirus (2019-nCoV)

Universal Screening for SARS-CoV-2 in Women Admitted for Delivery

SARS-CoV-2 in pregnancy: symptomatic pregnant women are only the tip of the iceberg

Presumed Asymptomatic Carrier Transmission of COVID-19

COVID-19 transmission through asymptomatic carriers is a challenge to containment. Influenza Other Respir Viruses

Asymptomatic COVID-19 infection in late pregnancy indicated no vertical transmission

An Analysis of 38 Pregnant Women with COVID-19, Their Newborn Infants, and Maternal-Fetal Transmission of SARS-CoV-2: Maternal Coronavirus Infections and Pregnancy Outcomes

Age-related difference in the rate of coronavirus disease 2019 mortality in women versus men

Effect of non-pharmaceutical interventions to contain COVID-19 in China