RSV (or Respiratory Syncytial Virus) is a virus that commonly causes coughs and colds. In healthy children and adults, it usually gets better by itself, but in babies it can cause chest infections that may need to be treated in hospital and can be life-threatening. In the UK, between 20 and 30 babies die of RSV every year. 

Babies cannot be vaccinated against RSV, but having the vaccine while you are pregnant protects your baby against RSV after they are born. When you are vaccinated, your immune system makes antibodies that protect you against RSV. These antibodies cross the placenta and also protect your baby. 

You can get the RSV vaccine at any time between week 28 of your pregnancy and your due date. 

You can have the RSV vaccine at the same time as your other pregnancy vaccines, such as whooping cough and flu, but it’s best to get your vaccine as soon as you are offered it. 

In many areas, your vaccine will be given by your GP practice. However, some hospitals have now set up special 'vaccination clinics' so you can receive your vaccine when attending your routine antenatal appointments. If they have a vaccination clinic at your booking hospital, your midwife will discuss this with you at one of your appointments.  

You can also ask your midwife about the RSV vaccine at any of your appointments or contact your GP yourself if you haven’t heard from them. 

The RSV vaccine has been carefully tested to find out how much protection it gives babies in their first few months of life.

In a clinical trial comparing active vaccine to a version without the active ingredient, RSV vaccination during pregnancy reduced the chance of babies under three months old getting severe RSV by more than 80%. 

Real world data from the first year the RSV vaccine was offered in the UK found that RSV vaccination in pregnancy reduced the chance of babies being hospitalised with RSV by 72%.

When the RSV vaccine was tested in a clinical trial, it did not increase the chance of pregnancy loss, pregnancy problems or health problems for babies after birth. There were slightly more premature babies in the vaccine group (2.1%) than the comparison group (1.9%). This difference was most likely to be due to chance, but nonetheless, the rate of preterm birth following RSV vaccination has been carefully monitored in the general population. In the USA, a comparison of 13,996 people vaccinated in pregnancy compared to 13,996 unvaccinated controls found no increased risk of preterm birth in the vaccinated group. 

Like all medicines, vaccines can cause side effects, but not everyone will experience them. Common side effects of the RSV vaccine (affecting more than 1 in 10 people) are:   

• Pain, redness or swelling at the site of the injection 

• Headache 

• Muscle pain 

• Nausea 

These side effects may be unpleasant if you experience them, but it is important to know that they are not dangerous for you or your baby, and having any of these does not mean that you have caught RSV. These side effects can be managed with paracetamol and usually go away within 1-2 days. 

Most people who are offered the RSV vaccine can have it. The only people who should not have the RSV vaccine are those who have had a serious allergic reaction (anaphylaxis) to a previous dose of the RSV vaccine, or an ingredient of the vaccine.  

Different kinds of RSV vaccines are offered to different groups. The vaccine you will be offered is called Abrysvo. The most important ingredient of Abrysvo is a small part of the virus, which has been made in a laboratory, called the prefusion F protein. Because this is only a small part of the virus, it cannot cause an infection but still allows your immune system to learn what the virus looks like and make antibodies against it. These antibodies cross the placenta to protect your baby. 

The other ingredients are: 

• Water 

• Sodium and tromethamine salts, used to make the liquid of the vaccine as salty and acidic as body fluids 

• Table sugar (sucrose) and sugar alcohol (mannitol), used as stabilisers 

• Polysorbate, used to hold the vaccine ingredients together (an emulsifier) 

• Residual amounts of cell contents from the cells in which the active ingredient (prefusion F protein) was made 

The RSV vaccine offered in pregnancy is called Abrysvo. Abrysvo does not contain any animal products.

The RSV vaccine offered in pregnancy is called Abrysvo. Like all vaccines routinely offered in the UK, Abrysvo does not contain mercury.