Resurgence of Influenza: A Closer Look at the B-Type strain

As spring unfolds, a resurgence of influenza, particularly the B-type strain, is raising concerns among health officials. Recent data indicates a significant increase in influenza cases, especially affecting school-aged children and adolescents. Experts emphasize the importance of preventative measures and vaccination, even for those previously infected with other influenza types.

Key Statistics and Trends

According to recent data, the number of influenza-like illness (ILI) cases has surged in recent weeks.As of the 14th week of 2025 (March 30 – April 5), the number of patients with influenza symptoms was 16.9 per 1,000 outpatients, surpassing the epidemic threshold of 8.6. This marks a four-week consecutive increase as March.

The most affected demographic is school-aged children and adolescents, with incidence rates of 56.1 and 53.8 per 1,000, respectively. While adults and the elderly show comparatively lower rates, vigilance remains crucial across all age groups.

Respiratory virus surveillance reveals that the influenza virus detection rate has been climbing steadily. The overall detection rate for the 14th week reached 22.5%,with B-type influenza accounting for a significant 21.1%. In contrast, A(H1N1) PDM09 and A(H3N2) strains show a much lower detection rate of 0.7% each.

Understanding the B-Type Influenza Virus

Unlike influenza A viruses, which can infect both humans and animals, influenza B viruses primarily infect humans. This can lead to slightly different symptoms and transmission patterns. While both types can cause seasonal epidemics,understanding the specific strain circulating is crucial for effective prevention and treatment.

Expert Recommendations and Preventative Measures

Health authorities are strongly advocating for basic respiratory hygiene practices, including frequent hand washing, proper coughing etiquette, and mask-wearing. Vaccination remains a cornerstone of prevention, even for individuals who may have been previously infected.

According to health officials, the currently circulating B-type influenza strain exhibits a genotype similar to that covered by the seasonal influenza vaccine. This suggests that vaccination can provide significant protection against infection. Furthermore, the absence of antiviral resistance mutations indicates that available treatments should remain effective.

As the influenza infection rate in children and adolescents is high, children need thorough prevention of precautionary rules in schools and homes.

Ji Young-mi,Head of Disease Control

For children aged 6 months and older who have either not been vaccinated previously or have only received one dose,a two-dose vaccination course is recommended. The national vaccination support program is scheduled to continue until April 30th, offering accessible vaccination options.

Recognizing Symptoms and Seeking Treatment

It is crucial to seek prompt medical attention if influenza symptoms are suspected. Common symptoms include a sudden fever (38°C or higher), cough, and sore throat. High-risk groups, such as those with weakened immune systems, are particularly vulnerable to serious complications like pneumonia.

Here’s a checklist for prevention and response:

• Be aware of respiratory symptoms such as cough, sore throat, and runny nose.
• Monitor for systemic symptoms like body aches,muscle pain,and fatigue.
• Watch for sudden listlessness or loss of appetite.
• If a family member is diagnosed with influenza, isolate the infected individual.
• Regularly disinfect frequently touched objects.

The Importance of Vaccination and hygiene

The current surge in B-type influenza highlights the ongoing importance of vaccination and adherence to basic hygiene practices. By taking these preventative steps, individuals can protect themselves and help to mitigate the spread of the virus within the community.