Seasonal influenza is a major concern for many people, especially families with young children. To help prevent the impact of this disease, the National Institute of Hygiene and Epidemiology has identified the influenza vaccine as an important vaccine that should be included in the national immunization strategy.
Although this vaccine is not currently included in the expanded immunization program, many people have chosen to receive seasonal influenza vaccination through optional vaccination service packages.
So, what is the seasonal influenza vaccine? What are the benefits of seasonal influenza vaccination? Let’s find out in the article below.
What is the seasonal influenza vaccine?
The seasonal influenza vaccine, also known as the flu vaccine, is a vaccine used to help prevent influenza in humans. It contains components of seasonal influenza viruses that are produced or isolated from real viruses but have lost their ability to replicate and cause disease.
The influenza vaccine usually begins to take effect about three weeks after administration. This is the time required for the immune system to produce sufficient antibodies against the virus.
Seasonal influenza vaccination should be given every year because antibodies against influenza viruses may gradually decline over time. In addition, seasonal influenza strains and variants continue to change each year, so regular vaccination helps maintain the body’s immunity. Currently, to achieve better disease prevention, countries and vaccine manufacturers are continuously researching and developing seasonal influenza vaccines.
Is seasonal influenza vaccination necessary?
Seasonal influenza vaccination is necessary to protect both individual and community health against the disease. Seasonal influenza viruses are highly contagious and can cause serious complications, especially in people with weakened health or older adults.
Historically, influenza has caused pandemics with devastating transmission. The 1918 Spanish flu pandemic was particularly severe, claiming tens of millions of lives worldwide. In recent years, influenza viruses have continued to evolve into multiple strains and variants, alongside other emerging respiratory viruses such as the coronavirus responsible for the COVID-19 pandemic.
According to epidemiological researchers, seasonal influenza will never disappear on its own. The virus continues to evolve in order to evade existing antibodies in the body. Seasonal influenza can cause dangerous complications such as pneumonia and pulmonary fibrosis, and may even affect cardiovascular function, increasing the risk of stroke or sudden cardiac arrest.
Seasonal influenza vaccination helps stimulate the immune system to produce antibodies against influenza viruses, thereby helping prevent infection or reduce the frequency and severity of flu symptoms. In addition, vaccination can also help reduce the risk of virus transmission to others.
The World Health Organization recommends annual seasonal influenza vaccination to minimize the impact of the disease on individual and community health.
Contact the hotline at 0949 416 006 or fill out the form below to register for vaccination.
Who should receive seasonal influenza vaccination?
According to WHO recommendations, seasonal influenza vaccination should be administered routinely and is recommended for everyone. Priority groups for vaccination include:
- Children over 6 months of age and older adults: These groups generally have weaker immune systems and are more vulnerable to influenza virus infection if they are not vaccinated regularly.
- Pregnant women or women planning to become pregnant: Influenza vaccination helps mothers minimize the risk of infection, thereby supporting fetal health and reducing the risk of congenital abnormalities.
People with chronic diseases, such as pneumonia, asthma, diabetes, or immunodeficiency, should have regular medical checkups and receive vaccination as prescribed. They should also avoid areas with active outbreaks and improve their health through gentle daily exercise.
Annual seasonal influenza vaccination is one of the most effective measures to strengthen the body’s protective “shield” against influenza viruses. In addition, receiving the flu vaccine on schedule can help minimize the risk of severe complications if infection occurs.
How long does the seasonal influenza vaccine remain effective?
Seasonal influenza vaccination is a necessary, safe, and effective preventive measure that has been proven over more than 60 years. According to the World Health Organization, seasonal influenza vaccines can provide more than 60% protection against infection and reduce the risk of severe, potentially fatal disease by nearly 80%. Thanks to this preventive measure, the annual number of influenza cases has decreased significantly, and severe flu-related complications have also become less common.
Because influenza viruses can continuously develop new, stronger, and more dangerous variants, influenza vaccines must be updated and improved regularly. In practice, influenza-related antibodies in the human body may retain only about 30% of their protective effect after one year and about 5% two years after vaccination. Therefore, to provide the most comprehensive protection against seasonal influenza, flu vaccination should be repeated every year, especially before the peak flu season.
People should also be aware that the seasonal influenza vaccine does not become effective immediately after injection. The body needs time to adapt and allow the immune system to produce sufficient antibodies. Protective antibody levels are usually achieved at least 15 days after vaccination.
When is the best time to receive seasonal influenza vaccination?
Currently, there is no specific cure for seasonal influenza. Available medications mainly help relieve symptoms. If medical care is not provided promptly, patients with influenza may face serious health risks, including death.
In fact, there is no single “best” time to receive seasonal influenza vaccination. To optimize protection, people should receive the flu vaccine every year, especially before the peak flu season. Children and pregnant women, in particular, should be fully vaccinated to help ensure comprehensive health protection.
Studies show that seasonal influenza viruses can spread easily through the air, especially in low humidity conditions. In Vietnam, with a tropical monsoon climate and high humidity throughout much of the year, influenza viruses can spread rapidly, particularly in spring. Health experts in Vietnam warn that peak flu seasons often occur around March to April or September to October, when rainfall is high and temperatures are favorable for viral growth.
Common influenza vaccines used in Vietnam
In Vietnam, four vaccines are commonly used for seasonal influenza vaccination: Influvac Tetra, GC Flu, Ivacflu-S, and Vaxigrip Tetra. Among them, Vaxigrip Tetra is an upgraded version of Vaxigrip and can protect against four influenza strains, including A/H1N1, A/H3N2, Yamagata, and Victoria. The remaining vaccines can protect against three influenza viruses, including two influenza A strains, A/H1N1 and A/H3N2, and one influenza B strain, either Yamagata or Victoria. Let’s learn more about these vaccines.
Vaxigrip Tetra
Vaxigrip Tetra is a seasonal influenza vaccine manufactured by Sanofi Pasteur, originating from France, and is recommended for people aged 6 months and older. This vaccine helps prevent infection or reduce the severity of disease caused by four influenza virus strains if they enter the human body, including two influenza A strains, A/H1N1 and A/H3N2, and two influenza B strains, Yamagata and Victoria.
Each dose of Vaxigrip Tetra is 0.5 mL, and the vaccination schedule varies by age:
- Children from 6 months to under 9 years of age: Two doses are required, with the second dose given 1 month after the first. Parents should also ensure annual booster vaccination.
- People aged 9 years and older: One dose should be given each year.
With the advantage of protecting against four influenza virus strains, Vaxigrip has been widely used in more than 100 countries and territories since 2016.
Influvac Tetra
Influvac Tetra is a seasonal influenza vaccine manufactured by Abbott, a pharmaceutical company based in the Netherlands. Influvac Tetra contains antigenic components from different seasonal influenza viruses, including influenza A and influenza B viruses. The vaccine helps stimulate the immune system to respond and produce antibodies against these seasonal influenza viruses.
In Vietnam, the Influvac Tetra vaccination period usually begins in September and lasts until December, before the seasonal influenza outbreak period. Each dose is 0.5 mL and is administered as follows:
- Children from 6 months to under 9 years of age: Two doses per year, with the second dose given at least 4 weeks after the first, followed by annual booster vaccination.
- People aged 9 years and older: One dose should be given each year.
Note: The booster dose should be administered at least 12 months after the previous dose.
GC Flu
GC Flu is a seasonal influenza vaccine manufactured by Green Cross Corporation, a pharmaceutical and medical device company from South Korea. This vaccine contains antigenic components from three seasonal influenza viruses, including two influenza A viruses and one influenza B virus. Similar to the vaccines mentioned above, GC Flu vaccination should be considered between September and December each year.
GC Flu is recommended for children aged 3 years and older and adults. The vaccination schedule is as follows:
- Children from 3 to 9 years of age: Two doses are required, with the second dose given at least 1 month after the first. Parents should also remember to have their child receive annual booster vaccination.
- Children over 9 years of age and adults: One dose is required, followed by annual booster vaccination, with each subsequent dose given at least 12 months after the previous one.
Ivacflu-S
Ivacflu-S is a seasonal influenza vaccine manufactured by Vietnam’s Central Pharmaceutical Joint Stock Company No. 1, or VACO. It is produced according to Good Manufacturing Practice, or GMP, standards of the World Health Organization and is widely used in Vietnam.
Ivacflu-S is recommended annually for seasonal influenza prevention, especially during winter and spring, which are peak periods for influenza outbreaks. Unlike the vaccines mentioned above, healthcare specialists recommend Ivacflu-S for people aged 18 years and older, with annual booster vaccination.
Important notes on seasonal influenza vaccination
Injection site for seasonal influenza vaccination
Seasonal influenza vaccines are usually administered in the upper arm, specifically into the deltoid muscle. Injecting the flu vaccine at this site helps improve absorption and vaccine effectiveness. The seasonal influenza vaccine should not be injected into the leg, as this site may not ensure optimal safety or vaccine efficacy.
Seasonal influenza vaccination can be performed at healthcare facilities, including hospitals, medical centers, clinics, and other centralized healthcare facilities. In some cases, agencies, companies, or organizations may also arrange seasonal flu vaccination for employees and members as part of routine or special vaccination programs.
Side effects after seasonal influenza vaccination
Side effects after seasonal influenza vaccination are usually mild and short term. After vaccination, some people may experience reactions such as pain and swelling at the injection site, redness or warmth of the skin around the injection area, lightheadedness, headache, fatigue, discomfort, joint or muscle pain, mild fever, vomiting, or a mild rash.
These reactions are usually not serious and often resolve on their own after a few days. To reduce the risk of side effects, individuals should receive seasonal influenza vaccination at an experienced healthcare facility and consult a doctor or nurse if they have any health concerns.
However, if any severe reactions occur after seasonal influenza vaccination, such as difficulty breathing, swelling of the face or throat, persistent rash, angioedema, nausea, or dizziness, patients should contact a healthcare facility immediately for timely examination and treatment.
Individuals who should not receive the vaccine
Although seasonal influenza vaccination has been proven safe and effective, some individuals should not receive the vaccine or should exercise caution before vaccination. These include:
- People with allergy or a severe reaction to any vaccine component, such as gelatin, antibiotics, or other ingredients.
- People with severe immunodeficiency, such as cancer patients undergoing treatment, patients with inherited immunodeficiency, or individuals using immunosuppressive medications.
- Infants under 6 months of age, because maternal antibodies transferred through pregnancy and breast milk may still remain in the body.
- People who have received another vaccine within the past 2 weeks.
In addition, during pre vaccination screening and post vaccination monitoring, doctors should pay special attention to:
- People with egg allergy.
- People with Guillain Barré syndrome.
In these cases, anyone with concerns or questions should consult a doctor or nurse before deciding to receive the vaccine.
Note: The information provided in this article by Hong Ngoc General Hospital is for reference purposes only and is not intended to replace professional medical diagnosis or treatment.
Follow the Facebook fanpage of Hong Ngoc General Hospital for more useful information: https://www.facebook.com/BenhvienHongNgoc
