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New Covid-19 pregnancy vaccine study will provide peace of mind for mums to be

Published: 24 May 2021


The first Covid-19 vaccine study in the UK recruiting pregnant women launched last week at St George’s, as well as across several National Institute for Health Research sites, including Guy’s and St Thomas’ NHS Foundation Trust and King’s College Hospital NHS Foundation Trust. The phase 2/3 study aims to further understand the safety, tolerability and immunogenicity of the Pfizer-BioNTech Covid-19 vaccine in healthy pregnant women, with approximately 235 volunteers involved throughout the UK.

The Vaccine Institute at St George’s, University of London and St George’s University Hospitals NHS Foundation Trust, has run multiple Covid-19 vaccine studies since the beginning of the pandemic, and has long-standing expertise in maternal vaccinations.

Speaking on the study, Professor Asma Khalil, Principal Investigator of the trial at St George’s, said: “This trial will seek to provide the evidence that can give mothers peace of mind when it comes to Covid-19 vaccinations. While there is now considerable evidence around the safety of the Pfizer and Moderna vaccines in pregnancy, this study will provide more information for the Pfizer vaccine around the immunity provided to mothers and their babies.”

Following updated guidance from the Joint Committee on Vaccination and Immunisation (JCVI) released in April, pregnant women are now offered approved Covid-19 vaccines at the same time as the rest of the UK population, based on their age and clinical risk group. Real-world data from the United States has been collected, in which over 100,000 pregnant women have been vaccinated (mainly with mRNA vaccines including Pfizer-BioNTech), without any safety concerns raised.

The role of this placebo-controlled study (Covid-19 Vacc Maternal Immunisation) is to provide more robust information on the vaccine immune response in pregnancy, as well as safety reporting and the potential transfer of maternal antibodies to infants.

Each participant enrolled in the study will initially receive either two doses of the vaccine or a placebo 21 days apart. All participants will be unblinded one-month post pregnancy, and those who were given the placebo jab (a salt water solution that does not contain any active ingredients) will receive the Pfizer-BioNTech Covid-19 vaccine.

Recruitment began last week in the UK. The study has already been running in the US since February. Research participants will be required to answer questionnaires about their health, provide blood samples, complete an e-diary and will receive extra monitoring while on the study, compared to those who receive a vaccine through the rollout.

All volunteers will need to visit their site for four planned visits before their baby is born and then two more follow up appointments after the baby is born.

Participants for the study will be identified via obstetricians and midwives at the hospital sites involved, with the study doctor determining whether each pregnant woman and their unborn baby would be suitable. Participation in the study is completely voluntary and participants can leave the study at any time.

Professor Khalil added: “It is very exciting that St George’s will be contributing to this, the first trial to recruit pregnant women to a Covid-19 vaccine study in the UK.  By investigating the transfer of antibodies across the placenta during pregnancy, we will be able to demonstrate the effectiveness of this vaccine in protecting mothers and their children, while improving our knowledge for the development of maternal vaccines in future.”

Professor Andrew Ustianowski, National Clinical Lead for the UK NIHR Covid Vaccine Research Programme, said: “We want to ensure we provide the data to guide the best way of protecting and vaccinating our entire population. This includes pregnant women and I am excited that this study is commencing as there are important questions still to be answered.

“The extra monitoring involved in being a participant in this study, along with the possibility of some pregnant women receiving a licensed and effective Covid vaccine before they would be eligible through the national rollout, is something we hope will attract potential volunteers to this important study.”

People wishing to volunteer to support clinical trials can sign up for information on Covid-19 vaccine trials with the NHS Covid-19 Vaccine Research Registry, developed in partnership with NHS Digital. Anyone living in the UK can sign up online to take part in the trials through the NHS, giving permission for researchers to contact you if they think you’re a good fit. Once you sign up, you can withdraw at any time and request that your details be removed from the Covid-19 Vaccine Research Registry.

To register interest in this trial at St George's, please reach out to the St George's Research Midwives by email ( or by phone (020 8725 3887).

This work extends a portfolio of work at St George’s to tackle the coronavirus pandemic. The University has launched a Coronavirus Action Fund to raise money for vital research into the pandemic and is actively seeking support for a broad research programme involving all parts of the University.

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