[Medical Q&A] What reactions will children experience after vaccination? What should I do?

Planner: Chinese Medical Association

Reviewer: Huang Lei, deputy chief physician, Fifth Medical Center, PLA General Hospital

After vaccination, your child may experience some common short-term reactions. These are normal signs that the immune system is building its ability to fight pathogens. They are usually mild and limited. Common reactions and how to deal with them are as follows.

1. Common reactions

1. Local reactions: After vaccination, redness, swelling, pain and nodules appear at the injection site.

Redness and swelling usually occur several hours to 24 hours after subcutaneous injection, often accompanied by pain. This reaction usually disappears within 48 to 72 hours.

Nodules often appear when administering vaccines containing adsorbents and can disappear within 7 days to 3 months. Some nodules may disappear after a longer period of time.

BCG suppuration and scars appear about 2 weeks after BCG vaccination. Redness and swelling appear at the injection site, followed by suppuration or ulceration. The scabs will fall off within 3 months and leave scars.

2. Fever: The fever reaction caused by the vaccine usually does not exceed 38.5℃ and will last for 1 to 2 days. It is rare for the fever to last more than 3 days.

3. Rash: Sparse rashes may appear 5 to 7 days after measles, mumps, and rubella vaccinations, and generally disappear in 7 to 10 days. Papules or herpes often appear 12 to 21 days after varicella vaccination, with a small number of papules or herpes, no scabs, and mild fever.

4. Others: You may experience symptoms such as fatigue, general discomfort, irritability, etc., which usually disappear after 1 to 2 days.

2. Treatment methods

1. Pay attention to rest, drink plenty of water, and strengthen observation to prevent secondary infection.

2. Local reactions generally do not require special treatment. For more serious local reactions, you can use a clean towel to apply hot compresses several times a day, each time for 10 to 15 minutes.

3. Local reactions caused by BCG should be treated with enhanced care, frequent changes of clothing, and strict prohibition of squeezing or cold or hot compresses. Locally formed pustules generally do not require special treatment and will gradually absorb or rupture into ulcers, forming scabs and falling off within 3 months to form scars. If local ulcers rupture, topical antibiotics can be used to prevent infection in severe cases.

4. Skin rashes and low-grade fever generally do not require special treatment. However, patients with severe systemic reactions or high fever should seek medical attention promptly.