Every year, as the weather shifts, so does the looming threat of influenza. One moment you’re feeling fine and the next, you’re bedridden with body aches, chills, and an unrelenting fever. It’s a familiar scenario that sends people rushing for remedies, but how much do we really know about the flu? While many people view it as just another seasonal nuisance, the flu is far more than a bad cold.

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To unravel the truth behind influenza, we spoke to Dr. Ma. Tarcela S. Gler, an infectious diseases specialist and Section Chief of the Infectious Diseases Department at Makati Medical Center. Read on as she sheds light on what we need to know to stay ahead of this viral menace.

What is influenza, and how does it differ from the common cold? 

Influenza is an upper respiratory tract infection caused by the Influenza virus. Its symptoms are body aches, cough colds and fever. A common cold is caused by several respiratory viruses and they usually have mild fever and there are no body aches.

How is influenza transmitted?

Influenza can be transmitted by droplets—when a person who is coughing or has colds coughs within three feet from contact, then they can be infected.

Have there been any significant changes or developments in influenza strains in 2025?

No changes so far in the strains.

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Can you provide information on any new strains detected this year?

There was an emergence again of bird flu seen in other countries.

READ: Bird Flu: What You Need to Know and How to Stay Safe

Recently, celebrities like Barbie Hsu and Chinese actor Liang Youcheng have been linked to severe flu complications. What might contribute to such severe outcomes in certain individuals?

As I mentioned above influenza is a viral infection of the upper respiratory tract. One can have a secondary bacterial infection during a bout of flu. Those at high risk for complications are the very young and the very old, or those with poor immune systems, including those undergoing chemotherapy or had AIDS.

Is there any connection between influenza and COVID-19?

No connection. They are both upper respiratory infections with almost similar symptoms but caused by different viruses. One is caused by the influenza virus, the other is caused by the coronavirus.

Can a person be infected with both viruses simultaneously?

Not usually. But if several respiratory viruses are circulating in the community (for example COVID-19 and Influenza), some people can be co-infected by both viruses.

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What measures can individuals take to prevent contracting the flu?

The most effective measure is available to us which is flu vaccination. This is available for senior citizens for free in the local health centers and most employees in their offices. A flu vaccine for the year is made available to us by mid-March and this is also the best time to get a flu vaccine since our flu season is usually in September to December.

Other measures that are as important are handwashing, wearing masks in public places when it is flu season, and avoiding being exposed to people with respiratory infections—social distancing.

How effective is the annual flu vaccine, and who should receive it?

The flu vaccine's effectiveness varies from year to year and from host to host. For the year 2023 to 2024, the vaccine effectiveness of flu was 42%. There are years that it has gone up to 60%. This is based on breakthrough infection as the endpoint being measured. Effectiveness is also affected by the host as well as the endpoint, that one is measuring. It can reduce hospitalization by 58%.