Fever After Varicella and MMR Vaccination in Infants

Fever after receiving the varicella (chickenpox) and MMR (measles, mumps, and rubella) vaccines at 1 year of age?

Hello Doctor, my baby received the varicella and MMR vaccines on February 18.
Starting from February 22, the temperature has been fluctuating between 36.5 and 38 degrees Celsius.
On the evening of February 27, the temperature exceeded 38 degrees (the highest recorded was 38.6 degrees, and I administered some fever-reducing medication).
On February 28, the fever subsided during the day, but the urine appeared slightly yellow, and I noticed some yellow mucus on the diaper and around the urethra.
Is this normal? (On February 27, the appetite was poor, but for the other days, the appetite and energy levels were normal.) Additionally, sometimes my baby seems to exert a bit when urinating, which is accompanied by shivering; is this a normal phenomenon? I would appreciate your clarification.
Thank you!

Sheila, 0~9 year old female. Ask Date: 2017/02/28

Dr. Pei Rensheng reply Pediatrics

Hello, the possible side effects of the varicella (chickenpox) and MMR (measles, mumps, and rubella) combination vaccine may occur approximately 4 to 12 days after vaccination.
Symptoms may include fever or a rash.
If a fever occurs, it typically lasts for 1 to 2 days and is not associated with yellow mucus from the urinary tract.
I am concerned that your baby may be experiencing a urinary tract infection, and I recommend seeking medical attention for a urinalysis.
Wishing you good health and happiness! Sincerely, Dr.
Pei Ren-Sheng, Attending Physician, Pediatrics, Taoyuan Hospital, Ministry of Health and Welfare.

Reply Date: 2017/02/28

More Info

After receiving the varicella (chickenpox) and MMR (measles, mumps, and rubella) vaccines, it is not uncommon for infants to experience mild fever as a side effect. The vaccines can stimulate the immune system, leading to a temporary increase in body temperature. Typically, fever may occur within 5 to 12 days after vaccination, and it usually resolves within a couple of days. In your case, the fever starting on February 22 and peaking on February 27 aligns with this expected timeline.

The fever you described, fluctuating between 36.5°C and 38°C, is generally considered mild. However, the peak temperature of 38.6°C does warrant some attention, especially since it was accompanied by a decrease in appetite on that day. It is important to monitor the fever and ensure that your baby remains hydrated and comfortable. The use of antipyretics, such as acetaminophen, can help manage the fever and alleviate discomfort.

Regarding the yellow urine and the presence of yellow mucus in the diaper area, this could indicate a few possibilities. While mild dehydration can lead to concentrated urine that appears darker, the presence of mucus might suggest a urinary tract infection (UTI), especially if it is accompanied by any discomfort during urination or if your baby seems to be straining. UTIs are not uncommon in infants and can present with fever, irritability, and changes in urine appearance. Given these symptoms, it would be prudent to consult a pediatrician for a urinalysis to rule out any infection.

As for your observation that your baby sometimes seems to strain while urinating and experiences shivering, this could be related to several factors. Infants may occasionally exhibit signs of discomfort or straining due to normal variations in bowel or bladder function. However, if this behavior is frequent or associated with crying, discomfort, or changes in urination patterns, it is advisable to seek medical advice.
In summary, while mild fever after vaccination is generally expected, the additional symptoms of yellow urine and mucus warrant further investigation. It is always better to err on the side of caution when it comes to the health of your infant. If you notice any worsening of symptoms, persistent fever beyond a few days, or any signs of distress, do not hesitate to seek medical attention. Your pediatrician can provide the best guidance based on a thorough evaluation of your baby's condition.

Similar Q&A

Fever After Vaccination: What Parents Should Know About Infant Reactions

Hello, doctor! My baby is two months old. He received the 13-valent pneumococcal vaccine and the pentavalent vaccine the morning before yesterday, and he started having a fever last night, with a maximum temperature of 39 degrees Celsius. Could this be related to the vaccines, or...

Dr. Xiao Kaiwen reply Pediatrics
If fever occurs after administering the pentavalent vaccine and the 13-valent pneumococcal vaccine, it typically happens within 24 hours of vaccination and usually does not last more than 24 hours. Therefore, your child may have another illness causing the fever, and it is recomm...

Post-Vaccine COVID-19 Diagnosis in Children: What Parents Should Know

Hello Dr. Hsiao, I have twin babies who just turned one year old. They received the varicella and measles vaccine on July 14. Baby B had a fever from July 16 to July 18, and Baby A also developed a fever on July 18. During a doctor's visit on July 18, they were tested and fo...

Dr. Xiao Kaiwen reply Pediatrics
A one-year-old infant is still very young, and their immune system is not fully developed. It is important to be cautious of the warning signs of severe illness in the case of a COVID-19 infection (though it is emphasized that the likelihood of severe illness is extremely low, so...

Concerns About Vaccine Errors in Infants: What Parents Should Know

My daughter is currently over 9 months old. She was taken to receive the measles vaccine but was instead administered the measles, mumps, and rubella (MMR) vaccine, which is typically given at 12 to 15 months of age, along with the first dose of the Japanese encephalitis vaccine....

Dr. Zhao Yongkang reply Pediatrics
Dear Ms. Ivy, 1. Please have the physician check for any other symptoms of infection. 2. Generally speaking, if the vaccination schedule is not followed correctly and the child does not exhibit any specific symptoms, there should be no major issues, but observation is still nece...

Understanding Chickenpox in Infants After BCG Vaccination

Hello doctor, my son is currently over five months old. He received the BCG vaccine last Friday, and unexpectedly, he developed chickenpox a week later. Is there any conflict between the BCG vaccine and chickenpox in his body? What should I be aware of? Thank you.

Dr. Xiao Kaiwen reply Pediatrics
The BCG vaccine and varicella (chickenpox) do not conflict with each other. Aspirin and other salicylate medications should not be used as antipyretics. Complications of varicella include pneumonia, encephalitis, secondary bacterial infections, and sepsis. Therefore, the dangerou...