“Flu” stands for the infectious disease caused by influenza viruses that are transmitted via droplets. In a densely populated place like Hong Kong where getting around is a breeze, viruses are more than easy to spread around. When we talk or sneeze, droplets would fall on places where others can touch or come into contact easily, meaning the transmission speed could be very fast. People who have a weak immune system, such as the elderly and patients with chronic diseases, have greater chances of developing complications after being infected, and so the flu could become fatal to these groups of people.

Not only Influenza A and B, but summer and winter versions

There are 2 major types of influenza, A and B, and it is the speed of virus mutation that decides which is more common. Influenza A’s viruses mutate at a faster speed so it’s likely to be more common and lead to more serious symptoms. In Hong Kong, the flu is more common from January to April and July to August¹. Past observations tell us that more people were infected in the winter influenza season and fortunately the number of serious cases was not overwhelming. But we must not let our guard down in the summer season - in 2017, it was more severe than the winter season and indirectly led to exceeded ward capacity, a public hospital crisis.

How to differentiate flu from a cold

A cold and flu share similar symptoms like a sore throat and runny nose. But the flu would go beyond the upper respiratory tract and cause discomfort all over the body, including bone pain. Flu symptoms also emerge within a very short period of time and lead to high fever and weak limbs.

Prevention starts from personal hygiene

You may have heard of all these precautions time and again but they are effective in preventing the flu – use soap or alcohol-based handrub to clean your hands when needed, wear a mask and stay at home if you have symptoms of respiratory tract infection, and consult a doctor if the condition persists or worsens.

In addition, vaccines also play an important role in flu prevention. Every year, WHO forecasts which types of flu viruses are most likely to be circulating in the coming year, helping the pharmaceutical and medical circles prepare targeted vaccines. Accurate forecasts could lead to 90% prevention rate but there was a time when the rate dropped to 30%.

Are you at high risk of catching the flu?

Flu viruses mutate constantly so we have to deal with different flu viruses every season. This is why the medical circle and government encourage people aged 6 months and above to get flu vaccination annually, in particular for these high-risk groups: medical personnel, chronic disease patients, pregnant women, people over 50 and under 12.