Vaccines that may cause fever in your child

Vaccines have improved the lives of millions of children around the globe. Today, it is hard to imagine that people actually suffered from diseases like Smallpox. Owing to the efforts of the Ministry of Health, there has been a complete eradication of diseases like Polio, and much more are on the verge of eradication.

Medicines vs Vaccines

When we talk about medicines, they are generally given after the person is afflicted with the malady. A few are given to prevent the disease. So, most of the medicines are not needed unless you need treatment. Vaccines, however, are given to prevent the disease in the future. And the way they work is quite interesting. Before we look into the side effects of vaccines especially fever, let us quickly understand how vaccines work.

Controlled exposure

When there is any infection in the body, the body’s immunity takes care of it by reacting to the pathogens in various ways. The end objective is to remove the bacteria or viruses that cause harm to the body. The immune system is better prepared, so to say, if the body already knows about the enemy – in this case, a pathogen. That is why, generally speaking, there is no second bout of Chickenpox. 

However, not every disease is as benign as Chickenpox. In a few cases, it is imperative that the body knows everything it can about a few nasty bacteria and viruses. And that is where vaccines come in the picture. A vaccine is ‘an antigenic substance prepared from the causative agent of a disease or a synthetic substitute, used to provide immunity against one or several diseases.‘

Imagine a vaccine as a captured enemy weapon. The immune system will get an opportunity to analyse the weapon and develop countermeasures, or an immune response in case the infection occurs. This immune response to a few vaccines will cause the body to heat up – a defence mechanism aimed at getting rid of the infection, commonly termed as fever. And that is why some vaccines cause fever.

Vaccines likely to cause fever

Most of the vaccines in the National Childhood Immunisation Schedule will cause a very mild reaction. A few can cause fever and other symptoms, and it is good to anticipate them than panic later on. 

1# DTaP Vaccine

If not given separately, DTaP is given as a 5 in 1 vaccine that will provide your child with an immunity against Polio, Haemophilus influenzae type b, in addition to Diphtheria, Pertussis and Tetanus. It may also be a part of 6 in 1 vaccine, where, along with these 5, Hepatitis B vaccine is included as well. 

It is quite common to get a fever after the DTaP vaccine. In fact, 1 in 4 children gets mild to moderate fever after the vaccine. According to the reported cases to CDC, ‘these problems occur more often after the 4th and 5th doses of the DTaP series than after earlier doses. Sometimes the 4th or 5th dose of DTaP vaccine is followed by swelling of the entire arm or leg in which the shot was given, lasting 1-7 days (up to about 1 child in 30).‘

2# MMR vaccine

 This vaccine, given after your child’s first birthday, may cause a slight fever in 1 out of 6 children immunised with this. It provides immunity against Mumps, Measles, and Rubella, three of the most painful childhood infections. The next dose is given three to six months after the first dose. 

3# PCV 

The Pneumococcal Conjugate Vaccine provides an immunity against Pneumococcal diseases, a group of serious infections that may cause, pneumonia, meningitis, and middle ear infection. 1 in 3 children would experience mild fever while 1 in 20 would suffer from a high-grade fever. 

Optional vaccines that may cause fever

A few optional vaccines are also offered in Singapore. Among these, the vaccines that may cause mild fever are Varicella (chickenpox) vaccine and Meningococcal vaccine. 

Needless to say, any vaccine can cause fever. So, if your child develops a fever after a vaccine not mentioned here, there is nothing wrong with your baby. It just means that your baby is flexing her immunity-muscle and getting ready to face the real world. That said, if the fever persists for more than 24 hours, please contact your doctor. 

Preparing for vaccination

While your child may not have to do much for the vaccination, you, as a parent, have a bit of a planning to do! Here are 4 things you need to do to prepare for the vaccination.

1. Take half a day off. A ‘time-chit’ looks like a lucrative option, given that it only takes a small time for the vaccination. However, your baby will need you afterwards. So plan the vaccination in such a manner that you spend at least 3-4 hours with your baby after the jab.
2. Dress the baby in loose clothes. It is a hassle to remove the clothes just before the jab and put them on a crying baby. The best way to dress the baby for a vaccination is a onesie with the thighs exposed. This way, you don’t have to worry about undressing the baby.
3. Prepare a feed/for a feed. If you are breastfeeding, locate a room where you can feed after the vaccination. If you are using a bottle, keep it handy. The baby will need some pacification after the painful prick. 
4. Buy Paracetamol. If your doctor forgets to prescribe some, ask for it, especially if your baby is getting a vaccine known to cause fever. At every visit, check the correct dosage for your baby. It depends on the weight, so the dose that worked last time might be insufficient now.

Mums and dads, let us know if you have any more questions regarding vaccines in the comments below.