New study into COVID-19 vaccine for pregnant women

Date: 16/09/2021

The country’s largest clinical study investigating the best gap between first and second COVID-19 vaccine doses for pregnant women is being launched Monday 20 September, in Milton Keynes.

The Preg-CoV study will take place at Milton Keynes University Hospital, and is supported by the National Institute for Health Research (NIHR) and backed by £7.5 million of government funding. Led by St George’s, University of London, the study will provide vital clinical trial data on the immune response to vaccination at different dose intervals – either four to six weeks or eight to 12 weeks. This data will help determine the best dosage interval and tell us more about how the vaccine works to protect pregnant mothers and their babies against COVID-19.

Pregnant women are more likely to develop severe COVID-19 or die from the disease, but are excluded from clinical trials with new vaccines. This means there is currently very limited clinical trial data on the immune response and side effects caused by the vaccines for these women.

The trial will involve over 600 pregnant women being vaccinated, across 14 NIHR-supported sites, with either the Pfizer/BioNTech or the Moderna vaccine. They will be closely monitored by health professionals throughout their pregnancy and following the birth, with the safety of the women taking part in the study the utmost priority.

Following 140,000 pregnant women being vaccinated in the US and no safety concerns being raised, the Pfizer/BioNTech and Moderna vaccines were recommended by the independent experts at the Joint Committee on Vaccination and Immunisation (JCVI) for pregnant women in the UK. Over 62,000 pregnant women in England have now been vaccinated – similarly, with no safety concerns.

Data published last week by NHS England and the University of Oxford shows no pregnant women who have had both doses of a vaccine have been admitted to hospital with COVID-19. Only three have been admitted after having their first dose, meaning 99% of those admitted to hospital have not received a jab. The Preg-CoV participants will need to be between 18 and 44-years-old, be generally healthy and be between 13 and 34 weeks pregnant on the day of vaccination. They will receive two doses of a COVID-19 vaccine (or one dose if they’ve already had their first) at either the shorter interval of four to six weeks, or the longer interval of eight to 12 weeks.

They will be scheduled to attend nine visits in total and will be required to complete an electronic diary between visits on any symptoms. They will also be given a 24-hour mobile number so they can contact one of the trial team at any time if they have concerns. The scientists behind the trial will analyse blood samples from the participants and one blood sample from their newborn babies, alongside samples from breastmilk. They will use the samples to help understand more about how the vaccines are protecting both pregnant women and potentially also their babies from COVID-19, with initial results expected by the end of the year.

The study is open for applications from volunteers via the study’s website. Participants will also be recruited to the study by invites sent through the NHS COVID-19 Vaccine Research Registry, which allows research teams to speak to suitable volunteers who have signed up to be contacted about taking part in vaccine studies.

  • Extensive real-world data shows vaccines are safe and highly effective for pregnant women
  • New government-funded clinical trial investigating best COVID-19 vaccine dose interval for pregnant women launched in England
  • Research shows pregnant women more likely to become seriously ill from COVID-19 and 99% of those in hospital due to COVID-19 are unvaccinated

Mr Ghaly Hanna, Obstetrics & Gynaecology Consultant at Milton Keynes University Hospital, said: “Current evidence indicates that it is safe for pregnant women to received approved COVID-19 vaccines, but we would like to know more about why this is the case and, in particular, when vaccinations should be administered, and this trial will provide us with more data in this regard. Given that pregnant women are at an increased risk of serious COVID-19 symptoms, this study represents an important chance to obtain more information to help us to protect pregnant women and their babies.”

Chief Investigator and Professor of Paediatric Infectious Diseases at St George’s, University of London, Professor Paul Heath said: “Tens of thousands of pregnant women have now been vaccinated in both the US and the UK with no safety concerns reported, but we still lack robust, prospective clinical trial data on COVID-19 vaccines in pregnant women. This includes the best schedule to use to maximally protect them against COVID-19. We are extremely pleased to commence the Preg-CoV trial, which aims to fill these gaps in our knowledge and will ultimately inform policy recommendations on the optimal use of COVID-19 vaccines in pregnancy.”

Professor Nick Lemoine, Medical Director, NIHR Clinical Research Network, said: “The fact that every participant in this study receives an approved vaccine will give volunteers peace of mind that they are protected from the virus and that they can take confidence in the safety of these vaccines, and the monitoring involved in the study. Vaccine studies like this remain crucial for researchers to gain more information on the best intervals and methods to help protect the whole population against COVID-19. It is thanks to the continued dedication and commitment of volunteers that we are at this stage of research and the NIHR is very grateful for their efforts. The NHS COVID-19 Vaccine Research Registry continues to help us reach out to potential participants and recruit to additional studies as we keep moving forward, and we encourage interested members of the public to sign up to be contacted at”

Dr Pat O’Brien, Vice President of the Royal College of Obstetricians and Gynaecologists, said: “We now have robust data of nearly 200,000 women from across the US and the UK, who have received the COVID-19 vaccine with no safety concerns. This tells us that both the Moderna and Pfizer vaccines are safe in pregnancy. However, more research is needed to monitor and understand how pregnant women respond to the COVID-19 vaccine. We welcome this trial as the next step in further monitoring the protection provided by the vaccine, to understand the risk of any potential adverse side effects, and observe the immune response within those who are pregnant and their babies. We encourage all pregnant women to get vaccinated, as the protection that it provides against COVID-19 to both mother and baby outweigh the risks. We are seeing more pregnant women being admitted to hospital with COVID-19, and we know that the Delta variant is causing more pregnant women to have severe illness than previous strains of the virus. We hope that this research will help to gain the confidence of pregnant women that the recommendation of vaccination in pregnancy is based on robust evidence.”

Site List:

  • St George’s University Hospitals NHS Foundation Trust
  • Milton Keynes University Hospital NHS Foundation Trust
  • University Hospital Southampton NHS Foundation Trust
  • St Michael’s Hospital, University Hospitals Bristol and Weston NHS Foundation Trust
  • Liverpool Women’s NHS Foundation Trust
  • Leeds General Hospital, Leeds Teaching Hospitals NHS Trust
  • St Helier Hospital, Epsom and St Helier University Hospitals NHS Trust
  • Imperial College Healthcare NHS Trust
  • Princess Royal Hospital Team, Shrewsbury and Telford Hospital NHS Trust
  • Royal Free NHS Foundation Trust
  • The Royal Cornwall Hospitals NHS Trust
  • Royal Preston Hospital, Lancashire Teaching Hospitals NHS Foundation Trust
  • Manchester University NHS Foundation Trust
  • Birmingham Heartlands Hospital, University Hospitals Birmingham NHS Foundation Trust

Notes to Editor:

Volunteers can sign up to the trial here:

  • The trial was commissioned by the Department of Health and Social Care through the National Institute for Health Research (NIHR) and funded by the Vaccine Taskforce, with the study being undertaken by St George’s, as part of the National Immunisation Schedule Evaluation Consortium (NISEC).
  • Participants will be blinded to the vaccine they receive. The majority of participants will also be blinded to the interval between doses. This will be done by incorporating the routine whooping cough vaccine into the trial schedule. Participants will be followed up for one year after their baby is born.
  • NHS England research on pregnant women in hospital due to COVID-19 can be found here:
  • This trial has received ethics approval by the NHS Research Ethics Committee (part of the Health Research Authority), as well as approval from the Medicines and Healthcare products Regulatory Agency (MHRA).
  • Latest PHE stats on vaccine effectiveness can be found here:

About the National Institute for Health Research

The National Institute for Health Research (NIHR) is the nation’s largest funder of health and care research. The NIHR:

  • Funds, supports and delivers high quality research that benefits the NHS, public health and social care
  • Engages and involves patients, carers and the public in order to improve the reach, quality and impact of research
  • Attracts, trains and supports the best researchers to tackle the complex health and care challenges of the future
  • Invests in world-class infrastructure and a skilled delivery workforce to translate discoveries into improved treatments and services
  • Partners with other public funders, charities and industry to maximise the value of research to patients and the economy

Volunteering for COVID-19 vaccine clinical trials:

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. It is helping large numbers of people to be recruited into trials, meaning more effective vaccines for coronavirus can be found as soon as possible.

The service was commissioned as part of the UK Government’s Vaccine Taskforce in conjunction with the National Institute for Health Research (NIHR) and the Northern Ireland, Scottish and Welsh Governments. 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.  The process takes about 5 minutes to complete.

More information can be found here.