Are vaccines normally used in pregnancy?
Yes. Pregnant people and people who are breastfeeding are already routinely and safely offered vaccines in pregnancy. For example, to protect against influenza (flu) and whooping cough. Many of these vaccines also protect their babies from infection. These vaccines, like the COVID-19 vaccines, are non-‘live’ vaccines, which are generally considered safe in pregnancy. Find out more about vaccinations in pregnancy.
How is COVID-19 vaccination being monitored in pregnancy?
Up to 31 March 2021, in the UK, healthcare professionals who met a person who had been vaccinated in pregnancy recorded this via their UK Obstetric Surveillance Service (UKOSS) reporter for the joint UKOSS/UKTIS study. Pregnant people who had been vaccinated (up to and including 31 March 2021) could also report directly to UKTIS.
You can register directly with the MHRA Yellow Card Vaccine Monitor.
Another reporting mechanism for healthcare professionals is the PHE Inadvertent Vaccination in Pregnancy (VIP) system.
As of April 2021, pregnancy status is recorded in the national vaccination programme to make sure pregnant people and their babies’ outcomes can be followed up.
Does it matter which vaccine I have?
The Joint Committe on Vaccination and Immunisation (JCVI) advises that it is preferable for all pregnant people in the UK to be offered the Pfizer-BioNTech or Moderna mRNA vaccines, where available. This is because these vaccines have been given to over 275,000 pregnant women in the US and UK and the data have not raised any safety concerns.
If you have already had one dose of AstraZeneca (before you became pregnant or earlier on in pregnancy), you are advised to complete vaccination with a second dose of AstraZeneca – see below for more information.
I have already had one dose of the AstraZeneca vaccine before or earlier in my pregnancy. I am now pregnant and due my second dose. What should I do?
The UKHSA published an update to the Green Book on Immunisation on 14 December 2021. This confirms that pregnant people who have already received a dose of AstraZeneca vaccine can have AstraZeneca for their second dose or 1 of the mRNA vaccines (Pfizer or Moderna). Evidence suggests that those who receive mixed schedules make a good immune response.
Pfizer and Moderna vaccines are the preferred vaccines for eligible pregnant people of any age. This is because of more extensive experience of their use in pregnancy. There are no reported concerns with the AstraZeneca vaccine in pregnancy, but there is less published data with this vaccine.
You are strongly recommended to complete your primary vaccination course with a second dose of any available vaccine to make sure you have maximum protection against COVID-19.
Is COVID-19 vaccination safe and effective for pregnant women and their babies?
Robust real-world data from the United States – where over 177,000 pregnant women have been vaccinated mainly with mRNA vaccines, such as Pfizer-BioNTech and Moderna – have not raised any safety concerns.
Therefore, the Joint Committee on Vaccination and Immunisation (JCVI) advises that the Pfizer-BioNTech or Moderna mRNA vaccines should be offered to pregnant women in the UK, where available.
The UK Health Security Agency (UKHSA) (formally Public Health England) have reported that more than 84,000 pregnant women in England have received at least one dose of COVID-19 vaccination.
Public Health Scotland have reported that more than 19,000 pregnant women have received a vaccine, with no serious adverse effects recorded. New safety data published on 25 November 2021 by the UKHSA showed that in August 2021, 22% of women who gave birth were vaccinated.
The initial clinical trials which showed that COVID-19 vaccines are safe and effective did not include pregnant women. As the COVID-19 vaccines were not tested in pregnant women, we cannot say for sure that they work as well in pregnant women as they do in other adults. However, more recent studies showed that pregnant women who had the vaccine made antibodies against COVID-19, suggesting that the vaccine is effective in pregnancy. Recent studies also showed that pregnant and non-pregnant women had similar mild side-effects from vaccination.
Covid-19 vaccines are not ‘live’ vaccines so cannot cause COVID-19 infection
COVID-19 vaccines do not contain ingredients that are known to be harmful to pregnant people or to a developing baby. Studies of the vaccines in animals to look at the effects on pregnancy have shown no evidence that the vaccine causes harm to the pregnancy or to fertility.
The COVID-19 vaccines that we are using in the UK are not ‘live’ vaccines and so cannot cause COVID-19 infection in you or your baby. Vaccines based on live viruses are avoided in pregnancy in case they infect the developing baby and cause harm. However, non-live vaccines have previously been shown to be safe in pregnancy (for example, flu and whooping cough). Pregnant people are offered other non-live vaccines, such as those against flu.
Studies have shown that protective antibodies from vaccination do cross the placenta, helping with the baby’s immunity to COVID-19. We know that catching COVID-19 during pregnancy can cause severe illness in a pregnant woman which is why COVID-19 vaccine in pregnancy is so strongly recommended.
What do we know about the impact of COVID-19 vaccination on babies born to women who have been vaccinated in pregnancy?
As these are new vaccines, there are no studies yet on the long-term effects on babies born to women who had a COVID-19 vaccine in pregnancy. But as COVID-19 vaccines are not ‘live’ vaccines they cannot cause infection, and other non-live vaccines have been given to women in pregnancy for many years without any safety concerns.
The mRNA vaccines (Pfizer and Moderna) are also quickly broken down once they have been injected – within a few days of vaccination there will be no vaccine mRNA left.
Studies have shown that protective antibodies developed from vaccination can transfer from mother to baby across the placenta, and after birth through breast milk, helping with the baby’s immunity to COVID-19. The degree of protection this provides to the baby is unknown at present and more research is needed.
No increased risk of miscarriage, preterm birth or stillbirth caused by vaccination
The data available shows that if a pregnant person has the COVID-19 vaccine they are not at an increased risk of having adverse pregnancy outcomes. Research from across 13 studies in 5 countries, involving more than 100,000 people vaccinated in pregnancy, shows having the vaccine does not increase the risk of miscarriage, preterm birth or stillbirth. Nor does it increase the risk of a small-for-gestational age baby, or the risk of congenital anomalies.
One of these studies was from St George’s, University of London and published in the American Journal of Obstetrics and Gynecology (AJOG) on 9 August 2021. The research compared pregnancy outcomes for women who had received the COVID-19 vaccine and those who had not. They found there were no significant differences between the two groups, with no increase in stillbirths or premature births, no anomalies with development and no evidence of babies being smaller or bigger.
More research is being done, monitoring both the mother and baby’s health during pregnancy and for a year after the baby’s birth. We know that the vaccine is safe in pregnancy, but this is the next step in looking at the level of protection that the vaccine provides, what the best interval between doses is, and monitoring the immune response of both the mother and baby after the vaccine.
What are the possible adverse effects from COVID vaccines?
The COVID vaccines are known to have mild and short-lasting side effects, such as a fever or muscle ache lasting a day or two in non-pregnant people. Reports of serious side effects, such as allergic reaction or clotting problems, have been very rare.
Regarding serious blood clots, the JCVI has stated that "there are currently no known risk factors for this extremely rare condition, which appears to be an idiosyncratic reaction on first exposure to the AstraZeneca COVID-19 vaccine". This means that someone is not necessarily at higher risk of this serious side effect just because they have a higher risk of other blood clots, for example because they are pregnant. Because this side effect is so rare, we can't know the exact risk in pregnancy.
This information on the AstraZeneca vaccine may be less relevant for you now that the JCVI recommends that the Pfizer-BioNTech or Moderna vaccines are offered in pregnancy, where available.
The government has also advised that individuals under the age of 40 should be offered an alternative vaccine to the AstraZeneca vaccine, based on the risk/benefit ratio for that age group.
What should I do if I develop a reaction to the vaccine?
Like all medicines, vaccines can cause adverse effects. These are usually mild and do not last long. Very common side effects in the first day or two after your vaccine include: pain or tenderness in your arm where you had your injection, feeling tired and headaches, aches and chills.
You may also have flu-like symptoms and experiences episodes of shivering or shaking for a day or two. If you develop a fever (your temperature is 38C or above) you can rest and take paracetamol, which is safe in pregnancy.
You can report any suspected side effects through the Yellow Card scheme, which allows the Medicines and Healthcare Regulatory Agency (MHRA) to monitor side effects and ensure vaccines are safe.
If you are concerned about your symptoms, you can contact your GP or maternity team for further advice.
There have been reports of an extremely rare clotting problem associated with people receiving the Oxford AstraZeneca vaccine. If you experience any of the following from around 4 days to 4 weeks after any vaccination you should seek medical advice urgently:
- a new, severe headache which is not helped by usual painkillers or is getting worse
- an unusual headache which seems worse when lying down or bending over or may be accompanied by:
- blurred vision, nausea and vomiting
- difficulty with your speech
- weakness, drowsiness or seizures
- new, unexplained pinprick bruising or bleeding
- shortness of breath, chest pain, leg swelling or persistent abdominal pain
Are there any vaccine clinical trials or studies taking place in the UK?
Two trials of COVID-19 vaccines in pregnant women in the UK have launched and another is planned.
- A clinical trial by the vaccine manufacturer Pfizer launched across several National Institute for Health Research (NIHR) sites in the UK in May 2021. Women who participate in this study will be randomly assigned to receive either the vaccine or a placebo (this is a randomised controlled trial, or RCT). Those who received the placebo will then be offered the vaccine once they give birth, so that all the women participating will have received the vaccine either in pregnancy or shortly after giving birth. The role of this 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.
- A government-funded clinical trial investigating best COVID-19 vaccine dose interval for pregnant women was launched in England in August 2021. The study is being led by St George’s, University of London, and will gather more robust data on how best to protect pregnant women and their babies from COVID-19. The clinical trial will investigate the immune response to vaccination at different dose intervals, monitoring the protection provided by the vaccine for pregnant women and their babies.
- There are plans for a pragmatic trial of different vaccines in pregnant women, and full details of that trial will be available shortly.