Your baby's 12-week vaccinations: what to expect

Last modified on Tuesday 14 March 2023

A baby receiving an injection

Your essential guide to your baby's 12-week vaccinations, including information on which vaccinations they will have, what to expect after the vaccinations, and any other FAQs on their 12-week vaccinations.

Going for your baby's 12-week vaccinations can be daunting, and while you may have some idea of what to expect following your baby's 8-week injections, you're still likely to have questions about this set of vaccinations and how to prepare for them, as well as any side effects after the vaccinations.

The health of your baby is of course paramount, so we've dug into the research from experts like the NHS and Oxford Vaccine Group, to put together this handy guide of what to expect at your baby's 12-week vaccinations and why they're important, along with FAQs and top tips.

Baby vaccinations are still going ahead as normal despite COVID-19, as well as newborn screening appointments. It's important that you still attend – unless you, your child or someone you live with has symptoms of coronavirus. If so, let your GP practice know and they will be able to rearrange your appointment.


What vaccinations will my baby have at 12 weeks?

According to the NHS, at 12 weeks, your child will have the following vaccinations:

6-in-1 vaccine (2nd dose)

Following on from their first dose at eight weeks, your baby will now have their second dose of the 6-in-1 vaccine. This protects them against six serious childhood diseases - diphtheria, hepatitis B, Hib (Haemophilus influenzae type b), polio, tetanus, and whooping cough.

Injected into your baby's thigh, it gives very good immunity to those diseases, with immunity increasing from this second dose, and again following their 16-week dose of the vaccine.

The 6-in-1 vaccine is very safe for your baby, and there's no risk of them getting any diseases from it since it does not contain any live organisms.

RV (rotavirus vaccine, 2nd dose)

This oral vaccine is first given to your baby at 8 weeks, and now again at 12 weeks. It protects against rotavirus, which is a highly infectious stomach bug affecting babies and young children. Rotavirus commonly causes vomiting and diarrhoea, tummy ache and fever.

The rotavirus vaccine is very effective and provides good immunity to rotavirus – particularly after the second dose – and has had a significant impact on the number of cases of the disease since the vaccine was first introduced.

PCV (pneumococcal vaccine)

Your baby will have two doses of PCV, one at 12 weeks, and one at one year old. The childhood PCV protects against 13 strains of the pneumococcal bacterium, providing excellent immunity for children.

Pneumococcal infections can lead to serious conditions including pneumonia, septicaemia, and meningitis. At their worst, these conditions can cause permanent brain damage or even death.

The vaccine is very safe for your baby, and there's no risk of them getting any diseases from it since it does not contain any live organisms.

Netmums' official GP, Dr Kenny Livingstone comments:

'Many of the initial vaccines are combined within the ‘6-in-1 vaccine’ so there are fewer injections.

'The rotavirus vaccine involves a few drops of fluid in your baby's mouth – rarely do babies complain too much about it. ‘

What should I expect after my baby's 12-week vaccinations?

As with any vaccine, it is possible for your baby to experience some minor side effects following their 12-week vaccinations.

Side effects may include:

  • Sickness - following the 6-in-1 vaccine, some 1 in 10 babies may experience sickness after their vaccinations. If this is the case with your baby, make sure you keep them hydrated, with smaller feeds little and often, and keep them as comfortable as possible. This should not last longer than a day or so.
  • Fever - or a temperature over 38C is a possibility after your baby's vaccinations. If your baby develops a fever, give them infant paracetamol which helps to reduce their temperature, keep them cool in fewer layers, and offer extra feeds where possible.
  • Diarrhoea - if your child suffers from diarrhoea, allow them to have plenty of rest, and do carry on breast or bottle feeding. If they're sick too, try giving smaller feeds more often than usual.
  • Tiredness and irritability - your baby feeling extra sleepy and irritable following a vaccination is fairly common, but shouldn't last long. If your baby seems to be in pain, liquid paracetamol should help.
  • Crying - it is common for babies to cry after their injections, but nothing a feed and some cuddles can't help with.
  • Decreased appetite - a mild side-effect of the PCV vaccine and the 6-in-1 vaccine is a slight loss of appetite. This is temporary and your baby's appetite should return to normal within one to two days.
  • Redness/swelling at the site of injection - babies may have temporary redness, swelling and a small bump at the injection site. This isn't anything to worry about and should fade within a day or so.

It is important to bear in mind that these side effects may not happen at all, and even if they do, will be mild and short-lived, usually lasting one to two days max, so try not to worry.

Dr Kenny Livingstone says:

‘My top tip for all vaccines is essentially, distraction. As parents, you are the best ones that can support with this, try not to be too nervous as your baby will pick up on this prior to and during the consultation.

'Simply smiling and talking to/cuddling your baby will help. With all newborns, having their next feed available also helps reduce any stress and settles them quickly.

'If you need to breastfeed your child afterwards, the GP practice should also be able to provide a space for you to undertake this.'

Autism is NOT a possible side-effect of your baby's vaccinations, and there is no evidence to suggest links between the two.

Top tips in preparing for your baby's 12-week vaccinations

  • Dress baby in comfy, loose clothing that is easy to remove, since babies under 12 months have injections in the thigh.
  • Call your doctor's surgery or health clinic to let them know if someone else will be taking your child for their vaccinations.
  • Remember to take your personal child health record book along to the appointment (otherwise known as the red book).
  • Have some infant liquid paracetamol at home, just in case your baby suffers from side effects like a fever after their vaccinations.

FAQs for your baby's 12-week vaccinations

What are vaccines made of?

Vaccines contain a small part of the germs that cause the disease (e.g. a rotavirus vaccine contains small parts of the rotavirus itself). The germs in vaccines are either killed or weakened, and so won't make your baby unwell; they are in there to help your baby's immune system respond to, and build immunity to a specific disease.

According to the Oxford Vaccine Group, other ingredients in vaccines include small traces of antibiotics, egg and yeast proteins, formaldehyde, and acidity regulators.

All of these ingredients are perfectly safe in such small amounts and are needed to ensure the vaccine works properly. You'd be surprised how many normal, everyday foods like fruit and vegetables contain scary-sounding chemicals!

Do vaccines contain mercury?

Generally speaking, most childhood vaccines do not contain thiomersal (a mercury-containing compound). Originally, thiomersal was used as a preservative in some multi-dose vials of flu vaccines to prevent the growth of dangerous microbes, which can be deadly.

Today, except for some flu vaccines in multi-dose vials, no thiomersal (or mercury) is present in baby vaccinations, or the amount is close to zero.

How long do the side effects of the 12-week jabs last?

The side effects following immunisation are mostly mild and usually last one to two days. Most babies won't experience any at all. The most common side-effect is usually tiredness or irritability, or redness and swelling in the arm, both of which will not last long.

Some babies develop a fever, but this can be controlled with infant liquid paracetamol. If you are worried about new side effects that last beyond a couple of days, seek advice from your GP.

Do vaccines temporarily weaken the immune system?

Despite being a common worry among parents, scientific data shows that childhood vaccines have no adverse effects on children's immune systems.

Studies also show that having the recommended childhood vaccines in combination carries no greater risk for adverse side effects.

Can adults get rotavirus from the baby vaccine?

Although unlikely, you should take care when changing your baby's nappy; since the rotavirus vaccine is given orally, it's possible the vaccine will pass through your baby's gut and be picked up when they soil their nappy.

Having said this, the vaccine only contains a weakened form of rotavirus, so most healthy adults will not be harmed.

Those with weakened immune systems, however, should take extra care.

Is it OK to give my baby a bath after vaccination?

There is no specific advice to say you should not bathe your baby following vaccination, however, if your baby is experiencing side effects like fever, sickness or diarrhoea, it is not advisable to. Otherwise, a few hours after vaccination is fine.

Should I give my baby infant paracetamol before a vaccination?

You should not give your baby infant paracetamol before a vaccination, because your nurse or doctor will first need to check your child doesn't have signs of an existing infection – which could be a reason to delay vaccination.

After the second set of vaccinations at 12 weeks, the NHS recommends only giving your baby infant paracetamol if they are showing signs of side effects like a fever (although this is more common following the MenB vaccination at 8 weeks). Always follow the instructions on the packaging.

Need advice?

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What if my baby missed their 12-week vaccinations?

The NHS advises that it's best for babies to be vaccinated at the recommended ages of 8 weeks, 12 weeks, 16 weeks and 12 months old, as they're then protected from numerous serious diseases as early in life as possible.

Your baby's health and development checks are very important, as it's the opportunity to check that they're developing properly in their early months, as well as providing you with a chance to raise any questions or concerns.

If you've missed your baby's appointment for their 12-week vaccinations, try not to panic, as it's never too late to have it. Make an appointment with your GP or local child health clinic as soon as possible and they'll be able to advise you on when to book in.

How do vaccines work to prevent disease?

As a parent, you might be asking yourself how vaccines actually work to prevent disease.

In the simplest terms, typically, a vaccine will contain a weakened strain of the disease, which is safely injected into your baby to help them build up immunity so that if they come into contact with a disease, they will not contract it.

Vaccines greatly reduce the likelihood of infection as they work with the body's natural defences to safely develop immunity to disease, without compromising it. It is always advised that you immunise your baby at 8 weeks, 12 weeks, 16 weeks and 1 year old.

Your baby's vaccination schedule: what to expect and when

For more information on which vaccinations the NHS can give your baby, and when to expect them, check these articles:

A few sources for more information:

Looking for more information on baby vaccinations and immunisation? Get more info or chat with other parents in our Forum below.

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