August 5, 2020

expert reaction to study looking at genes in embryos and whether they are susceptible to SARS-CoV-2 infection in early pregnancy

A study, published in Open Biology, looked at genes in embryos and whether they are susceptible to SARS-CoV-2 infection in early pregnancy.

Dr Shamez Ladhani, Reader in Paediatric Infectious Diseases, St George’s, University of London, said:

“These are very early data on the potential for SARS-CoV-2 to infect human embryos and more work needs to be done to better understand the role of the virus in early pregnancy.

“We are already monitoring pregnant women with COVID-19 in the UK, through the periCOVID trial, and more work is being done worldwide.  It is vital that infants have long-term follow up from birth and through their early years to assess their neurodevelopmental outcomes and ensure that families have all the support they need.”

Dr Pat O’Brien, Consultant Obstetrician and Vice President of The Royal College of Obstetricians and Gynaecologists, said:

“During the pandemic there have been reports describing the possibility of vertical transmission of SARS-CoV-2 but we still await proof.  This study provides further evidence as to the mechanisms which could underly this.  At present there is no evidence of increased risk of miscarriage or fetal anomaly due to SARS-CoV-2.  There is some evidence that during the pandemic there has been an increase in the rate of adverse outcomes, but the reasons for this are thought to include accessing appropriate maternity care as well as any potential direct effect of COVID-19.  Studies in the UK and across the world have shown that babies born to mothers with SARS-CoV-2, even if they test positive, are no more likely to be unwell than the babies of mothers without coronavirus.”

Prof Christoph Lees, Professor of Obstetrics, Imperial College London, said:

“This is an intriguing laboratory based study using newly developed culture platforms that enable researchers to look at the expression of genes in the early human embryo.  Some genes may be implicated in how the SARS-CoV-2 virus enters cells.  The study finds that these genes might be present at a very early stage and raises the possibility – if this were the case – that the embryo might be susceptible to the virus.

“It is important to say that this work is at a very hypothetical stage – in other words there are more question marks than there are answers.  The study does not show that the SARS-CoV-2 virus either does or is more likely to infect embryo cells, but it suggests that there is a potential route through which it might.

“What appears possible in a laboratory study is a long way removed from what might actually happen in the human embryo.  It is also important to say that there has as yet been no evidence of an increased risk of miscarriage or for that matter other fetal problems from the tens of thousands of human pregnancies that we know have been exposed to SARS-CoV-2 so far.

“We know that even if mothers are infected, transmission of the virus to baby is unlikely and even if the baby does become infected, the outcomes are generally good so from this study there is no reason for women to be concerned or change their reproductive plans.”

Prof Ian Jones, Professor of Virology, University of Reading, said:

“While this is a scientifically accurate study of when critical components required for SARS-CoV-2 infection are first switched on in the developing embryo, it has very little to do with any risk of vertical transmission by the virus.  Many viruses grow is foetal tissue as no immunity is present but they do not represent a risk as they do not cross the placenta.  SARS-CoV-2 is primarily a respiratory virus and while there have been occasional reports of intrauterine transmission the overwhelming evidence is that it is very uncommon and does not represent a significant risk.  To suggest otherwise borders on scaremongering.”

Prof Andrew Shennan OBE MBBS MD FRCOG, Professor of Obstetrics, Department of Women and Children’s Health, King’s College London, said:

“This work is well conducted science research that suggests the cells of babies in the womb can be infected by Coronavirus in early pregnancy if they are exposed to the virus.  However an increasing evidence base suggests it is rare for the virus to cross the placenta in pregnancy.  Even if fetal cells are infected, this research does not indicate they would be harmed.  Most cells make a complete recovery after being infected with a virus.  This includes with the coronavirus.  So far there have been many studies showing that babies are not at increased risk if their mother has coronavirus.  About 1 in 5 babies have to be delivered early as their mother is sick, but are unharmed by the virus.”

‘Expression of SARS-CoV-2 receptor ACE2 and the protease TMPRSS2 suggests susceptibility of the human embryo in the first trimester’ by Bailey A. T. Weatherbee et al. was published in Open Biology at 00:01 UK time on Wednesday 5 August 2020.

DOI: 10.1098/rsob.200162

Declared interests

Prof Christoph Lees: “Co-chief Investigator on the UKRI funded PAN-COVID pregnancy study.”

Prof Ian Jones: “No conflicts.”

Prof Andrew Shennan: “I have no conflicts of interest.”

None others received.