Many people who have received the flu vaccine may have wondered why it is necessary to get vaccinated every year. They just got vaccinated last year, so why do they need to get vaccinated again this year? To clear up this doubt, Dr. Suwannee Rattanachuwong, an internist at the General Internal Medicine Clinic, Phyathai 3 Hospital, has reasons to explain.
Current Influenza Situation
According to the outbreak data collected by the Department of Disease Control, in 2019, from January to February, there were 46,648 reported cases of influenza infection, with 4 deaths. In contrast, in 2018, the number of influenza patients was only 13,000-15,000, showing an increase of more than twice as much.
There is a severe outbreak every 10 years. In 2009, a global outbreak occurred, and Thailand had as many as 120,000 influenza cases. Additionally, fluctuating weather and increasing PM 2.5 dust are important factors that contribute to the spread of influenza.
Why do we need to get the flu vaccine every year?
This is because the influenza virus changes its strains every year, which is a normal cycle for the virus to adapt for survival. The virus cannot survive long in the natural environment and dies quickly, so it needs to find ways to infect the human body. This is why we need to protect ourselves by getting vaccinated to build immunity against the virus that changes every year.
When does immunity develop after vaccination?
The influenza virus has a very short incubation period, averaging about 1-4 days before symptoms appear. Therefore, it is crucial to build immunity before the virus enters the body. Normally, immunity develops 10-14 days after vaccination.
The earlier you get vaccinated… the lower the chance of infection
Although we cannot achieve 100% immunity, those who receive the flu vaccine tend to have milder symptoms if infected compared to those who are not vaccinated. Unvaccinated individuals are at higher risk of complications, hospitalization, or death than those who have been vaccinated.
Dr. Suwannee Rattanachuwong
Internist, General Internal Medicine Clinic
Phyathai 3 Hospital
