Doctor answers about seasonal flu vaccines that need to be vaccinated annually

seasonal flu - a common disease that cannot be overlooked

seasonal flu is an acute respiratory infection caused by the flu virus, which often flare up in the winter - spring. The influenza virus is spread mainly through drops taken from patients when they cough, sneathe or talk. With a high rate of infection, seasonal flu can lead to many dangerous complications such as pneumonia, respiratory failure, multiple organ failure and even death, especially in high-risk groups.

In 2024, Vietnam recorded 289,876 cases of seasonal flu. From the beginning of 2025 to now, there have been 912 new cases. Notably, at the Department of Infectious Resuscitation - 108 Central Military Hospital, many influenza patients with severe pneumonia complications and multiple organ failure have been recorded.

Dr. Nguyen Van Tuan, Department of Infectious Legend, Central Military Hospital 108, said that after vaccinating, the body will start producing antibodies for protective protective and immunity after about 2 weeks. The effective preventive effectiveness of the vaccine ranges from 32 - 60%, depending on the circulating virus strains. Although vaccines cannot protect 100% from the flu, it helps reduce the severity of the disease and the risk of hospitalization from 63 to 78%. However, the effect of the vaccine usually lasts no more than 1 year, about 6 months, so the annual reminders are essential.

Repeat vaccination against influenza every year

According to Dr. Nguyen Van Tuan, immunity has declined over time. The number of protective antibodies after vaccination has decreased, especially in children and the elderly - those with weaker immune systems.

influenza virus is constantly changing: The influenza virus is likely to change every year, causing immunity from old vaccines or from previous infections not enough to protect against new virus strains. Therefore, the influenza vaccine is updated annually to match the types of viruses in circulation.

Prevent outbreaks: Studies show that even people who have had the flu before are still at risk of re-accepting the new strain of the virus, causing serious outbreaks.

Global influenza monitoring centers monitor and identify the flu virus strains with the highest risk each year. The World Health Organization (WHO) relies on this data to recommend the composition of the new vaccine, helping to ensure the vaccine has the highest protection efficiency.

"The influenza virus changes every year, so vaccines need to be vaccinated before each influenza season to create timely immunity. In Vietnam, flu often flare up strongly in March - April and September - October. Therefore, the optimal time for vaccination is 2 weeks to 1 month before the flu season.

For women planning to become pregnant, they should get vaccinated against influenza before becoming pregnant. If you have not been vaccinated yet, you can get vaccinated against inactivity during the 3 months of pregnancy to protect both mother and baby. Newborns can receive antibodies from their mother after giving birth, helping to reduce the risk of flu in the first months of life," said Dr. Nguyen Van Tuan.