The influenza vaccine is a biological preparation used to prevent seasonal influenza. It primarily stimulates the human immune system to produce antibodies that combat the influenza virus. This vaccine targets the surface antigens of the seasonal influenza virus and is updated annually based on data from global influenza surveillance networks to ensure compatibility with circulating strains. Its main goals are to reduce infection risk, alleviate symptom severity, and lower the incidence of severe illness or death among high-risk groups.
This preventive method is suitable for all eligible populations, especially high-risk groups such as the elderly, pregnant women, and individuals with chronic illnesses, offering significant protective value. The vaccine is available in two main forms: injectable and nasal spray, with the choice depending on age and health status.
The influenza vaccines are mainly divided into three categories: Inactivated Influenza Vaccine (IIV), Live Attenuated Influenza Vaccine (LAIV), and Recombinant Influenza Vaccine. Inactivated vaccines use virus particles that have lost infectivity, while live attenuated vaccines contain weakened virus strains. Recombinant vaccines only contain surface proteins of the virus. These components stimulate B cells to produce antibodies and train T cells to develop immune memory against the virus.
After vaccination, it takes approximately two weeks for the body to produce sufficient antibodies, with protection lasting 6 to 8 months. Due to frequent genetic mutations (antigenic drift) of the virus, vaccines need to be updated regularly, so annual vaccination is recommended to maintain immunity. This active immunization significantly reduces community transmission and contributes to herd immunity.
The vaccine is suitable for all individuals aged 6 months and above without contraindications, especially the following high-risk groups:
The World Health Organization (WHO) recommends annual vaccination for high-risk groups and suggests concurrent vaccination with pneumococcal vaccines to enhance protection. This approach remains effective against antiviral-resistant strains and is the most effective current preventive measure.
The vaccine can be administered via intramuscular injection (usually in the upper arm) or nasal spray. Children over 6 months can receive the injectable form, while healthy individuals aged 2 to 49 years may choose the nasal spray. Regarding dosage:
The injection site may experience redness or pain, which usually resolves within 48 hours. The optimal vaccination time is before the end of October each year, but vaccination can be performed at any time during the year. Special populations such as immunocompromised individuals should follow medical advice to adjust their vaccination plan.
Main benefits include:
Compared to natural infection, vaccination can prevent severe symptoms such as high fever and pneumonia, and reduce the use of antiviral medications. Studies show that vaccinated individuals who do get infected tend to experience milder symptoms and shorter illness duration.
Common local reactions include pain, redness at the injection site, and mild fever, which usually resolve within 2-3 days. Some people may experience headache or muscle soreness, which are normal immune responses. Important considerations include: Severe egg allergy requires allergy testing prior to vaccination, and those with a history of epilepsy should inform their doctor.
The incidence of severe allergic reactions (such as anaphylactic shock) is less than one in a million, typically occurring within 15 minutes post-vaccination. Those with previous neurological or hematological adverse reactions should avoid vaccination.
Contraindications include: severe allergy to any vaccine component, acute febrile illness, or allergy to thiomersal (preservative). Prior to vaccination, inform your healthcare provider if you have allergies to eggs, embryonated eggs, or antibiotics (such as neomycin).
Immunocompromised individuals (e.g., HIV patients) may require higher doses, and those with a history of Guillain-Barré syndrome should be carefully evaluated. Post-vaccination, observe for 15-30 minutes at the vaccination site to promptly manage any allergic reactions.
Influenza vaccines can be administered simultaneously with other vaccines, preferably at different injection sites. There are no interactions with antiviral drugs (such as oseltamivir), but those on immunosuppressive therapy should inform their doctor. There are no direct interactions with NSAIDs (like ibuprofen), but use during fever should follow pharmacist instructions.
Patients undergoing chemotherapy or post-organ transplant immunosuppressive therapy should evaluate vaccine efficacy. When used with tetanus vaccines or other protein-based drugs, inform your doctor of your complete medication history to avoid allergic risks.
Clinical trials show that the vaccine provides about 50-60% protection against circulating strains of the current year, with seroprotection rates exceeding 70% for strains like H5N1. Long-term follow-up indicates a 60% reduction in influenza hospitalization rates and an approximately 18% decrease in cardiac events among cardiac patients.
Epidemiological data confirm that every 10% increase in community vaccination rate reduces community influenza transmission by about 25%. Even when vaccine strains do not perfectly match circulating strains, cross-protection can still be induced, reducing severe illness risk.
Short-term prevention can involve antiviral medications (such as oseltamivir) used as post-exposure prophylaxis within 72 hours of contact. Long-term alternatives include improving personal hygiene and reducing gatherings, though these are less effective than vaccination. In special cases, monoclonal antibody drugs may be considered, but only for immunodeficient individuals.
Immunity from natural infection lasts only 1-3 years and may lead to severe illness, whereas vaccination offers a safer form of active immunity. These alternatives are generally reserved for cases where vaccination is not feasible.
It is recommended to confirm your health status before vaccination. If you have a fever or acute illness, delay vaccination. Those with egg allergies or a history of severe allergic reactions to vaccine components should consult a doctor for risk assessment. Infants under 6 months cannot be vaccinated; their caregivers should get vaccinated to provide indirect protection. On the day of vaccination, avoid fasting and bring previous vaccination records for reference.
What should I do if I develop redness or mild fever at the injection site after vaccination?Minor redness can be alleviated with cold compresses, and pain can be managed with painkillers as advised by a doctor. Mild fever usually subsides within 24-48 hours; rest and hydration are recommended. If experiencing difficulty breathing, widespread rash, or other severe allergic reactions, seek medical attention immediately and report suspected adverse vaccine reactions. Health authorities will provide follow-up assistance.
If I get a cold after vaccination, does it mean the vaccine failed?The influenza vaccine does not protect against other respiratory viruses such as coronaviruses or adenoviruses. It only targets the circulating influenza strains of the season. If symptoms match typical influenza (high fever, muscle aches), antiviral treatment can be initiated within 48 hours of onset, and symptoms should be monitored. The vaccine's effectiveness is about 40-60%, but it significantly reduces the risk of severe illness.
How long should I wait between receiving the influenza vaccine and other vaccines?It is preferable to wait at least 7 days between influenza vaccination and other injectable vaccines, but concurrent vaccination with pneumococcal vaccines is not contraindicated. Oral vaccines (such as rotavirus) are unaffected. If passive immunity agents like immunoglobulins have been administered, a minimum interval of 3 months is recommended before live vaccines. Specific scheduling should follow the vaccine instructions for the year and health authority guidelines.
Do chronic disease patients need to adjust their medication after vaccination?Chronic disease patients (such as those with diabetes or heart disease) generally do not need to change their routine medications after vaccination but should continue monitoring their underlying condition. Immunocompromised individuals (e.g., dialysis patients) may require booster doses, and their healthcare provider will adjust vaccination strategies accordingly. If symptoms worsen post-vaccination, seek immediate medical evaluation to determine if related to the vaccine or underlying disease changes.
%201.svg)
Copyright © 2025 MedFrontiers. All Rights Reserved.
