June 25, 2024

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The adverse reaction of vaccines

The adverse reaction of vaccines

The adverse reaction of vaccines. Usually 1/3 of vaccine inquiries in hospital outpatients or clinics are vaccine adverse reaction.  For example, 

“Doctor, my family received the DPT vaccine yesterday, and the injection site is swollen today. Is there a problem with the vaccine? What should I do?”

“Doctor, my family got the measles vaccine a few days ago, and I got a lot of rashes today. Did the vaccine get measles?”

“Doctor, my family was vaccinated yesterday, and today I have a fever, am I okay?”

The adverse reaction of vaccines. Usually, 1/3 of vaccine inquiries in hospital outpatients or clinics are vaccine adverse reaction

Adverse reactions of vaccination are divided into two categories, general reactions and abnormal reactions.

General Reaction

A general reaction is a reaction that occurs after vaccination and is caused by the inherent characteristics of the vaccine itself, which will only cause a transient physiological dysfunction to the body. Including systemic and local reactions, such as fever, general malaise, irritability, lethargy, loss of appetite, fatigue, local redness, swelling, and induration.

Abnormal Reaction

An abnormal reaction is an adverse drug reaction in which a qualified vaccine causes damage to the tissues and organs of the recipient during or after the implementation of the standardized vaccination, and the relevant parties are not at fault.

What will happen to the general reaction?

1 Possible reactions:

The vaccine is a foreign body to the body. After vaccination, it will stimulate the body and cause symptoms of systemic or local reactions. Common reactions include redness and pain at the vaccination site, low fever, crying, lack of energy, fatigue, lethargy, etc.

2. Situations that can be handled by oneself ( for reference only):

It is generally mild and does not require special treatment. It can be relieved by drinking plenty of water and a local dry and cold compress and then dry and hot compresses (induration caused by BCG vaccine cannot be applied with heat). Parents should calm their children patiently and pay attention to changes in their body temperature, generally 2-3 Days are getting better.

Specifically, the following three situations:

1. Fever (when the axillary temperature is less than 38.5℃) (because the ear temperature is generally 0.5-1℃ higher than the axillary temperature, it is not recommended to measure the ear temperature), should strengthen the observation, take proper rest, drink plenty of water to prevent secondary diseases.

2. Local reactions with redness and swelling diameter and induration less than 15mm generally do not require any treatment.

3. For local reactions with redness and swelling diameter and induration> 15mm, a dry towel can be used to pad the area within 24 hours of inoculation, and an ice pack can be placed on it for cold compress. After 24 hours of inoculation, switch to a “suitable temperature” towel for hot compress, several times a day, 10~ 15 minutes. The red and swollen area can also be applied with thin slices of potatoes (exposing the needle eye). (Knifes, cutting boards, and potatoes for cutting potatoes should be washed clean, but potato slices after cutting cannot be washed again), pay attention to hygiene to prevent infection.

If the local itching is severe and the child always wants to scratch, the following measures can be taken.
  • Measure 1: Trim your child’s nails and wash hands frequently. Keep your hands clean to prevent infection after the child is scratched.
  • Measure 2: Trimixin cream, or desonide cream, or cyproheptadine cream can be used according to the doctor’s recommendation. External use (twice a day) on the red and swollen area can relieve itching.

3. Circumstances that need to go to the hospital for treatment:

If the situation becomes serious and the following 3 situations occur, you should go to the hospital for treatment in time and notify the vaccination unit in time.

  • Fever (when the axillary temperature is ≥38.5℃) or ≤37.5℃ accompanied by other systemic symptoms, abnormal crying, malaise, convulsions, etc., you should go to the hospital for treatment in time.
  • If the redness, swelling, heat, pain or induration at the vaccination site does not get better, and it continues to aggravate, you should go to the hospital in time.
  • Cases deemed serious by other parents.
  • Special reminder:  If a child becomes ill after being vaccinated, it must be considered related to vaccinations, but it must not be subjectively determined to be related to vaccination, because it is possible that the child is already in the incubation period of the disease at the time of the injection, and he just became ill after the injection. Medically called “coincidence” “(It can be understood as “accidentally falling ill”), because it often occurs within a few hours or days of vaccination, causing many parents to delay the child’s condition because they think it must be related to the vaccination. So be sure to take your child to the hospital for treatment.

5. The most common questions from parents:

The vaccination is given in the community vaccination clinic. Why do we go to the hospital with an adverse reaction?

Because most community vaccination clinics are disease prevention institutions, and hospitals are treatment institutions. Some vaccination clinics do not have the qualifications to diagnose and treat diseases. Especially if the parents think that the adverse reaction is serious, please go directly to the hospital as soon as possible.

Years of outpatient work experience tells us that the most important adverse reaction is allergic reactions, especially acute anaphylactic shock, laryngeal edema, allergic purpura, etc. Therefore, we must obey the outpatient schedule and stay for 30 minutes after vaccination!

Of course, don’t panic. The rare and serious abnormal reaction rate is about 1/100 million. Parents who have a normal reaction will have to work hard for a while, but they will get health protection. Compared with the harm of disease, everything is worth it.


Two questions for which the vaccination doctor is almost impossible to give you definite answers:

1. My child was fine before the injection, and fell ill as soon as the injection returned. Is it caused by the vaccine?

2. My child got fever, rash, or local swelling after the injection, is it all right?

The human body itself is very complicated, and each individual’s physique varies greatly. Is the illness caused by a vaccine? Unless a serious abnormal reaction is identified by the expert group, no other institutions or individuals will be identified.

After the injection, I got fever, rash, and local swelling. Because the adverse reactions of diseases and vaccines are unpredictable, it is impossible for us to tell you “nothing”.

If you find the above situation, you can consider following the treatment suggestions above (it is better to go to the hospital or clinic).


Two more special vaccines: BCG and DPT


About 2 weeks after inoculation with BCG vaccine, local swelling and infiltration may appear, followed by suppuration, forming small ulcers, most of which will scab (stuck) after 8-12 weeks. This process is actually a normal reaction after artificial infection with Mycobacterium tuberculosis. Generally, no treatment is required, but the local area should be cleaned and dried to avoid scratching to prevent secondary infection.

Local redness and swelling caused by BCG vaccination should not be applied with heat to prevent infection. If the pustule has a large ulcer and does not heal for a long time, and there is eczema-like itching around the wound, seek medical advice promptly. If lymph nodes are enlarged or ruptured on the same side of the vaccination, anti-tuberculosis treatment is required.

Special DTP (including Quad-component and Penta-component) vaccines containing this ingredient:

Each child needs 4 shots. The first 3 shots are vaccinated when they are 3, 4, and 5 months old; the fourth shot is vaccinated when they are 18 months old. Local redness and swelling tend to occur more later, especially the fourth shot. Redness and induration are most likely to occur.


1. The components in the vaccine are highly immunogenic;

2. The vaccine contains adjuvants, which have the effect of attracting inflammatory cells. After the arrival of inflammatory cells, they release inflammatory substances and stimulate inflammation such as redness and swelling;

3. Vaccines contain toxoids, which are easy to stimulate and cause inflammation.

Treatment measures:

1. The general low-heat and induration shall be handled by referring to the “self-handling situation”;

2. If high fever or local suppuration occurs (very rare), seek medical attention in time. Generally, it is necessary to repeatedly extract the pus and debride the wound in severe cases. The course of the disease is longer, and it can be absorbed and healed.

Any vaccination may have adverse effects or reactions, but the probability of serious abnormal reactions from vaccination is extremely low. When you agree to the injection, it is deemed that you have accepted the possible, potential, but very low probability serious risk of the injection. Once there is a serious abnormal reaction (severe abnormal reaction needs to be identified by the relevant national department), compensation will be made in accordance with the relevant national laws and regulations.

In order to reduce the incidence of adverse reaction, please make sure that you are healthy, have no history of serious allergies, have no perianal abscesses, thrush and other immunocompromised diseases before vaccination. Be sure to watch for 30 minutes after vaccination!

(source:yimiaoquan. Attention: This article for reference only, please contact your doctor first)