Regarding the flu vaccine, parents are most concerned about these issues.

Original Zhi Ling Jie’s children’s medicine circle

We often say that the full name of the flu is influenza. The symptoms of the flu are similar to those of the common cold, accompanied by high fever (above 39℃), sore throat, cough, sneezing, runny nose, headache, muscle pain, general fatigue and other symptoms. Compared with the common cold, the flu has a faster onset, stronger infectivity and more serious symptoms. Vaccination is an effective measure to prevent influenza virus. Children aged 6 months to 2 years are high-risk groups, so parents are advised to actively vaccinate their children. September-October is the best time to vaccinate them. Parents should pay attention to the arrival of local influenza vaccines and make an appointment in advance. Recently, many parents have consulted some questions about influenza vaccine in the background, and summarized them, hoping to help everyone.

Will influenza vaccination reduce immunity?

Influenza vaccine will not reduce immunity.

Under normal circumstances, the human body is not immune to influenza virus. It is suggested to vaccinate against influenza every year because vaccination can enhance the "immunity". However, with the passage of time, the protective power of the vaccine gradually weakens and the immunity returns to the normal level, not because the vaccine reduces the body’s immunity.

Is trivalent good or tetravalent good?

At present, China’s "influenza virus split vaccine" and "influenza virus subunit vaccine" are trivalent, and "tetravalent influenza virus split vaccine" is tetravalent.

Four-valent inactivated vaccine has one more protection of influenza B virus than trivalent inactivated vaccine, so it is suggested to choose tetravalent inactivated vaccine first. However, if there is only trivalent vaccine in the local area, it is not recommended to postpone vaccination in order to wait for tetravalent vaccine.

It is best to use the same vaccine to complete the vaccination procedure in the same flu season, but if the first vaccine is out of stock, other vaccines can be used to complete the vaccination procedure, such as the first vaccine is tetravalent, the second vaccine is trivalent, or the first vaccine is viral, and the second vaccine is subunit, or vaccines from other manufacturers can be used.

Why do you get the flu after vaccination?

There are many types of influenza viruses, and influenza vaccines only cover the most common types, so the efficacy against influenza is not 100%;

The incubation period of influenza is usually 1~4 days. If you are infected before you produce enough antibodies, you may get the flu.

Other diseases such as the common cold can produce flu-like symptoms, and flu vaccines can’t prevent these diseases.

How many doses should I get the flu vaccine?

Children and adults over 9 years old only need one dose even for the first time;

Children ≥6 months and < 9 years old should receive 2 doses of influenza vaccine for the first time (at least 4 weeks apart, not both doses at one time); If the first dose was inoculated at the age of 8 years and 11 months, the second dose should be inoculated after 4 weeks;

Children ≥6 months and < 9 years old have been vaccinated with one dose of influenza vaccine in the past. Both China’s CDC and the Hong Kong Department of Health recommend one dose this flu season, while the US CDC recommends two doses.

Children ≥6 months and < 9 years old who have been vaccinated with two doses of influenza vaccine in the past (trivalent or tetravalent, whether they were vaccinated in the same flu season or two consecutive flu seasons) and the interval is ≥4 weeks, only one dose is required in this flu season. In other words, two doses of trivalent vaccine were inoculated before, and one dose of tetravalent vaccine was enough for the first time this year.

Can I get an "adult dose" if I am under 3 years old?

Children under the age of 3 can be vaccinated against influenza. Sometimes there is no vaccine under the age of 3 in the local area, so the staff may say that they can’t fight.

"Adult dose" influenza vaccine refers to a vaccine with a dose of 0.5 mL, and some vaccine instructions believe that the vaccine is used for adults and children over 36 months old. Although the experiment shows that there is no significant difference in safety, reactivity, local or systemic adverse reactions between children aged 6-35 months using 0.5mL dose and using 0.25mL dose of tetravalent inactivated influenza vaccine (IIV4), they should still be vaccinated at the age suggested in the instructions.

Note: The concept of "dosage" is different from that of "dosage times". The influenza vaccine listed in China, 0.25 mL dose is suitable for children aged 6~35 months, and 0.5 mL dose is suitable for children and adults aged 3 years and above. Children who need two doses of 0.25 mL influenza vaccine should be divided into two doses with an interval of ≥4 weeks (28 days), instead of one dose of 0.5ml..

How long should the interval between the second and first doses be?

The contents of the instructions are usually based on the results of clinical trials, and it is suggested that the interval between two stitches should be 2~4 weeks. The guidelines are recommended based on the latest research data, and it is recommended that the interval be at least 4 weeks. For children who need two injections, the instructions in the guide should prevail, and the interval should be at least 4 weeks.

Antibodies with protective level can usually be produced after 2~4 weeks of influenza vaccination. If the interval between the second dose and the first dose is more than 4 weeks, the time to produce antibodies with protective level will be delayed accordingly, but the final effect will not be affected. Just make up the second dose as soon as possible.

Can I take anti-influenza drugs after vaccination?

Inactivated influenza vaccine can be inoculated during the prevention and treatment of influenza antiviral drugs. However, live attenuated influenza vaccine should not be inoculated within 48 hours after using influenza antiviral drugs;

If you have been vaccinated with live attenuated influenza vaccine, you should not use antiviral drugs to prevent influenza within 14 days (if necessary, you can treat it) because antiviral drugs will affect the immune effect of live attenuated influenza vaccine.

Original title: "Parents are most concerned about these issues about influenza vaccine"

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