Influenza (referred to as "flu") isCaused by influenza virus infectionAcute respiratory infectious diseases.Influenza vaccination isAn effective means to prevent influenza.About influenza vaccination this winter and next springSome common questions,Fujian CDC answers are as follows↓↓↓
1. What are the antigenic components of trivalent and tetravalent influenza vaccines this year?
The trivalent influenza vaccine recommended by the World Health Organization (WHO) in 2023-2024 based on chicken embryos in the northern hemisphere consists of:
A/Victoria/4897/2022（H1N1)Pdm09 similar strain
A/Darwin/9/2021(H3N2)Similar strain
B/Austria/1359417/2021(Victoria department)Similar strain
The tetravalent influenza vaccine component contains two strains of B strain, namely the above three strains and B/Phuket/3073/2013.(Yamagata system)Similar strain.
Compared with the previous year, the vaccine component recommended by WHO in this year has been replaced with influenza virus subtype A(H1N1)pdm09 vaccine strain.
2. What kinds of influenza vaccines are available in 2023-2024?
Influenza vaccines listed in the world are divided into inactivated influenza virus vaccine, live attenuated influenza virus vaccine and influenza virus recombination vaccines.
According to the components contained in the vaccine, it is divided into trivalent and tetravalent influenza vaccines.
According to the production process, it can be divided into chicken embryo culture, cell culture and recombinant influenza vaccine.
Influenza vaccines used in China in the epidemic season of 2023-2024 include trivalent inactivated influenza vaccine (IIV3), tetravalent inactivated influenza vaccine (IIV4) and trivalent live attenuated vaccine (LAIV3).
Both IIV3 and IIV4 have 0.25ml dosage form and 0.5ml dosage form, and LAIV3 has 0.2ml dosage form.
3. Which key groups and high-risk groups give priority to influenza vaccination?
It is suggested that all people who are over 6 months old and have no contraindications should be vaccinated with influenza vaccine. Combined with the epidemic situation of influenza and the prevention and control strategy of multi-disease prevention, the harm of influenza should be reduced as much as possible.
Priority recommended key and high-risk groups:
1 medical personnel, including clinical rescue personnel, public health personnel, health and quarantine personnel, etc.;
2. Older people aged 60 and over;
3. People suffering from one or more chronic diseases;
4. Vulnerable people and employees in gathering places such as old-age care institutions, long-term care institutions and welfare homes;
5. Pregnant women;
6. Children aged 6-59 months;
7. Family members and caregivers of infants under 6 months old;
8. People in key places such as kindergartens, primary and secondary schools and supervision places.
4. What is the immune persistence after influenza vaccination?
The immunity acquired by human body after being infected with influenza virus or inoculated with influenza vaccine will decline with time, and the degree of decline is related to factors such as people’s age, physical condition and vaccine antigen.
A study on antibody dynamics of influenza vaccine in Australia showed that the antibody level induced by various vaccine strains reached a peak one month after vaccination, and began to decline about three months later. After vaccination for six months, the antibody level was still higher than the baseline, suggesting that the antibody protection level can be maintained for at least six months after vaccination.
A study in Taizhou City, Zhejiang Province also found that the antibody level mediated by some vaccine strains was still high after 6 months of influenza vaccination.
Studies have shown that the serum antibody level in the body decreased significantly after one year of influenza vaccination. Studies have shown that the decrease of serum antibody is related to the decrease of the number of bone marrow plasma cells, that is, the specific bone marrow plasma cells increased after 4 weeks of influenza vaccination, but decreased to the pre-vaccination level after 1 year.
In order to match the ever-changing influenza virus, one or more strains of influenza vaccine recommended by WHO will be updated in most seasons, and it also exists that the vaccine strains are exactly the same as the previous season.
In order to ensure the maximum protection of the vaccinated population, even if the composition of the influenza vaccine is exactly the same as that of the previous season, since the antibody titer produced by most vaccinators in the last vaccination has dropped significantly, it is still recommended to vaccinate before the arrival of the influenza season in that year regardless of whether the influenza vaccine was vaccinated in the previous season.
5. What are the requirements for the vaccination times of influenza vaccine?
Children from 6 months to 8 years old should be vaccinated with IIV vaccine: children from 6 months to 8 years old who are vaccinated with influenza for the first time should be vaccinated with two doses (two doses of the same vaccine should be selected) with an interval of ≥4 weeks; Children who have received one or more doses of influenza vaccine in 2022-2023 or before are recommended to receive one dose.
Vaccination of children aged 6 months to 8 years: No matter whether they have been vaccinated with influenza vaccine, only one dose is given.
Children and adults aged 9 and over only need one dose.
6. What are the taboos for influenza vaccination?
Anyone who is allergic to any ingredients contained in the vaccine (including excipients, formaldehyde, cracking agents and antibiotics) or has a history of severe allergic reaction to any kind of influenza vaccination is prohibited from vaccination.
Patients with acute diseases, severe chronic diseases or acute attacks of chronic diseases and fever are advised to be vaccinated after recovery or stable control of their condition. Patients with Guillain-Barre syndrome within 6 weeks after previous influenza vaccination are advised to be evaluated by a doctor before considering whether to vaccinate.
The following people are prohibited from being vaccinated with LAIV:
① Persons with low immune function due to drug use, HIV infection and other reasons;
② Children and adolescents who have been treated with drugs containing aspirin or salicylic acid for a long time;
③ Children with asthma aged 2-4 years;
4 pregnant women;
⑤ Those with a history of Guillain-Barre syndrome;
⑥ Those who used antiviral drugs such as oseltamivir and zanamivir 48 hours before inoculation, or those who used palamivir 5 days before inoculation, or those who used balosevir 17 days before inoculation.
7. Can influenza vaccine and other vaccines be vaccinated at the same time?
Inoculation with other inactivated and attenuated live vaccines:
Inactivated influenza vaccine can be inoculated simultaneously or sequentially with other inactivated vaccines and attenuated live vaccines; If two live attenuated vaccines are inoculated at the same time, the interval should be at least 4 weeks.
Inoculation with Covid-19 vaccine at the same time:
People aged 18 and above can be vaccinated with inactivated influenza vaccine and Covid-19 vaccine at the same time, and at the same time, they should be vaccinated at the inoculation sites of both limbs. For the minors who have been vaccinated with LAIV and under the age of 18, it is suggested that the interval between vaccination with Covid-19 and Covid-19 should be more than 14 days due to the lack of evidence at present.
8. When is the timing of influenza vaccination?
Usually, after 2~4 weeks of influenza vaccination, antibodies with protective level can be produced.
The time and duration of the annual peak of influenza activity are different in different parts of China. In order to ensure that the recipients can get immune protection before the high-incidence season of influenza, it is suggested that all localities arrange vaccination as soon as the vaccine is available, and it is best to complete immunization before the local influenza epidemic season. Vaccination units can provide immunization services throughout the epidemic season.
In the same influenza epidemic season, people who have completed the whole vaccination according to the vaccination procedures do not need to be vaccinated again.
9. Besides influenza vaccine, what other vaccines can be vaccinated to prevent respiratory infectious diseases?
In addition to influenza vaccination this winter and next spring, pneumococcal vaccine and Covid-19 vaccine are also recommended for the elderly and people with chronic basic diseases.
For children, it is suggested that non-immunization programs such as pneumococcal vaccine and Haemophilus influenzae type B conjugate vaccine should be inoculated on the basis of continuing immunization program vaccination. No matter whether it is an immunization program vaccine or a non-immunization program vaccine, the requirements of vaccination specifications should be strictly followed during the vaccination process.
10. How should we protect against influenza vaccine before it is produced?
Wear a mask scientifically. If you go to a closed environment and crowded places, take public transport or go to the hospital, it is recommended to wear a mask and pay attention to changing it in time.
Develop good personal hygiene habits. When coughing or sneezing, cover your mouth and nose with paper towels or towels. Wash your hands or disinfect your hands in time after touching public facilities such as elevator buttons and door handles, and after coughing or sneezing. In addition, daily attention should be paid to keeping the environment in the home and workplace clean, and opening windows regularly for ventilation.
Develop a healthy lifestyle. In daily life, we should keep enough sleep, adequate nutrition and proper physical exercise to enhance our physical fitness and improve our immunity.
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