Five-day-old embryos too can contract Covid-19, finds study
Embryos even as old as five days develop receptors that are known to provide an easy passage to the Sars-CoV-2 virus which causes Covid-19, finds a new study by ICMR-National Institute for Research in Reproductive Health (ICMR-NIRRH) carried out using 45 donated human embryos after in-vitro fertilization (IVF) procedure at fertility clinics.
Researchers said their findings indicate that embryos can get infected with Covid-19 in the womb from infected mothers and also during IVF procedure in laboratories which, according to them, increase the chances of a miscarriage or even failure to conceive in both natural and IVF-induced pregnancy.
Though no cumulative data is available about the total number of miscarriages recorded among Covid-19 infected pregnant women, a significant number of private and civic-run hospitals have witnessed such cases.
Receptor is a specific protein that provides an entry point to the virus to hook into and infect a wide range of human cells. Studies have found that Sars-CoV-2 infects the lungs through the receptor—angiotensin-converting enzyme 2 (ACE2) – and enzyme TMPRSS2.
The ICMR-NIRRH study—Expression map of entry receptors and infectivity factors for pan-coronaviruses in preimplantation and implantation stage human embryos published in the Journal of Assisted Reproduction and Genetics in May – found many cells of the embryos that fertilized as early as five days express the same receptors—ACE2 and TMPRSS2.
Dr Deepak Modi, lead investigator of the study, explained this new finding has established the fact that embryos are susceptible to contracting the infection either through vertical transmission (from the infected mother to the foetus in the womb) or horizontal transmission during artificial fertilisation process of the embryos in labs through IVF. “We have discovered that the same cells also have the necessary machinery to allow virus multiplication and growth inside the embryonic cells. This will harm the developing embryos and may cause their death. The team also found that along with ACE2, the cells of early embryos contain receptors for other coronaviruses making them highly likely to get infected,” said Dr Modi in response to an email.
Dr Manjiri Mehta, consultant gynaecologist and obstetrician, Fortis Hiranandani hospital, Vashi, said that she has seen a definite rise in first as well as second-trimester miscarriages and intrauterine deaths among Covid-19 infected mothers.
“This can be directly or indirectly related to the Covid-19 infection. The study indicates the virus can infect the human embryo in the lab. In pregnant women, the Covid-19 virus can impact in different ways such as vertical (mother to child transmission), immunological mechanisms, to name a few. This will certainly have an impact on infertility treatment. The real impact will be known once we have more data and studies to substantiate these claims or otherwise,” she said.
BYL Nair hospital, where more than 1,000 Covid-19 pregnant women have delivered babies, has also witnessed miscarriages. “We can’t firmly say if the miscarriages happened because the foetus contracted the infection from the mother in the womb. More studies need to be done to confirm vertical transmission among the foetus,” said Dr Ramesh Bharmal, hospital dean.
Researchers said their findings can help couples who seek IVF treatment and doctors practicing IVF.
In case of IVF labs, said Modi, the virus can spread from an asymptomatic carrier and the embryos can get infected. “The virus can stay alive on surfaces of the lab and cold chain like liquid nitrogen, where embryos are preserved. Once the virus gets in touch with the embryos, it can infect them and multiply, thereby creating a problem. There might be low pregnancy rates and poor embryo quality due to viral infection to embryos,” he added.
When a woman tests positive while undergoing IVF treatment, doctors suggest that couples delay the process until complete recovery. “There is a possibility that the virus can go inside the embryos from an infected mother. So, whenever a woman gets infected before conceiving, we ask them to halt the treatment for at least 1-2 months,” said Dr Richa Jagtap, clinical director, consultant reproductive medicine, Nova IVF Fertility, Mumbai. “Although the infection rate among pregnant women was more in the second wave compared to the first wave, we didn’t see any case where an embryo contracting the infection during the fertilisation procedure in our labs,” she said.
However, IVF experts said all precautions are being taken considering the high risk associated with the fertilised embryos. ICMR issued guidelines for recommencing ART (assisted reproductive technology) services during Covid-19 pandemic.
“All procedures in laboratories are done through closed working chambers where the chance of embryos getting infected is almost zero. Also, the labs have high-efficiency particulate air filters which provide better safety against the microscopic viruses,” said Dr Kshitiz Murdia, chief executive officer and co-founder of Indira IVF.
He said all staffers have been vaccinated following ICMR guidelines, in addition to conducting RT-PCR tests on women before performing any complicated fertility procedures.
“We have started tele-consultation to avoid unnecessary crowding in clinics. For any emergency use for infected mothers, we have a separate chamber for video consultancy where a patient can virtually meet the doctors. We are in the process of acquiring RT-PCR testing kit which will get us results within 20 minutes,” said Dr Murdia.