[Health Column] Why did the flu vaccine change from quadrivalent to trivalent? A comprehensive overview of the reasons for the reduction in numbers and the actual preventive effects.

 

Hello, this is Director Choi Woo-hyuk.

 

💉 As flu vaccination season approaches, we're hearing a lot of questions like, "Why a trivalent vaccine this year?"

📌 In the past, quadrivalent vaccines were the standard, but now that the number has been reduced, there are concerns that the effectiveness may be reduced.

However, this change is closer to an 'optimization' than a downgrade.

There is clear evidence behind this in surveillance data from global health organizations.

From now on, I will slowly explain the reason.

 

Why are flu vaccines divided into quadrivalent and trivalent?

📢 Included in vaccine A distinction that refers to the number of types of viruses no see.

The quadrivalent and trivalent in the flu vaccine

👉 How many flu viruses are in the vaccine? It means.

• Past quadrivalent vaccines

  • Type A, Type 2

  • Type B 2

• Currently, there are three vaccines

  • Type A, Type 2

  • Type B 1

📌 So it looks like the number has decreased by one,
This change Selective adjustments to reflect trends That's the key point.

 

What is the scientific reason for the change from 4 to 3?

📢 Results excluding non-prevalent viruses no see.

 

Every year, the World Health Organization (WHO) predicts the flu viruses most likely to be prevalent that year and issues recommendations.

 

From the 2024–2025 season onwards

• Type A (H1N1, H3N2): Same as before

• Type B:

  • ❌ Excluding Yamagata series

  • ⭕ Only maintain Victorian series

The reason is simple.

Because the B-type Yamagata series has rarely been detected in humans no see.

 

Why was the B-type Yamagata series excluded?

📢 Because it was observed to have ‘virtually disappeared’ through objective surveillance.

 

According to data from the European Center for Disease Prevention and Control, etc.

In recent years

• B-type Victoria series detected in large numbers

• Type B Yamagata series is rarely confirmed

This does not simply mean “it has decreased”,  It is judged to be not actually popular It has been done.

 

📌 So WHO Rather than including one unnecessary virus species
Focusing on the currently prevalent virus I chose .

 

If it's a trivalent vaccine, won't the flu prevention effect be reduced?

📢 No, there is no basis for believing that the preventive effect has been reduced.

This is the part that most people are worried about.

But the trivalent vaccine
✔️ Contains only essential viruses
✔️ Designed to fit the current trend

 

in other words, It is more accurate to understand it as an 'optimized vaccine' that has removed unnecessary components.

 

Just because the number has decreased The scope of protection has not been significantly reduced.

 

Is this change a decision specific to a specific country?

📢 This is a standard that is being applied simultaneously by public health organizations around the world.

This transition to a trivalent vaccine

• WHO

• US CDC

• Korea Centers for Disease Control and Prevention

• Japan, UK, etc.

📌 A trend that is applied equally worldwide no see.

In that it is not a choice of a specific country or a specific hospital. There is no reason to be anxious.

 

FAQ

Q1. I had a 4-year-old last year, but this year I have a 3-year-old, so I'm worried. Will it be okay?

A1. Yes. With a reasonable composition, excluding viruses that are not currently prevalent, there is no reason to believe that the preventive effect is insufficient.

 

Q2. Would it be a better option to request the quadrivalent vaccine at the hospital?

A2. Current health guidelines recommend a trivalent vaccine, and there is no scientific reason to insist on a quadrivalent vaccine.

 

Q3. What is more important than the type of vaccine?

A3. More than any other family or species Vaccination at the right time This is the most important.

 

conclusion

✔️ The change from 4 to 3 is not a downgrade.
✔️ Except for non-prevalent viruses reasonable adjustment no see.
✔️ Health organizations around the world are applying the same standards.

 

💉 To prevent winter flu Rather than worrying unnecessarily Vaccination at the right time Focus on .
If necessary, you can get vaccinated after sufficient consultation with medical staff.

 

 

 

 

 

Director Choi Woo-hyuk

Graduated from Korea University's College of Life Sciences
Graduated from Kyung Hee University College of Medicine
Kyung Hee University Hospital Resident
Regular member of the Korean Society of Dermatology