Some health experts warned on Tuesday that the existing flu season is expected to continue into November and urged the public to get vaccinated as a preventive measure.

The Post looks at the different types of flu circulating in the city, what health experts say and how residents can protect themselves.

What is influenza B? How is it different from influenza A?

Both influenza A and B can develop into severe, life-threatening diseases. While influenza B is less common and more likely to cause milder illness, it can be severe in children and the elderly, according to respiratory medicine specialist Dr Leung Chi-chiu.

As there has been no major influenza B circulation since the start of the Covid-19 pandemic, herd immunity remains low, especially among children who have not been exposed to it since birth, he said.

The H3 subtype of influenza A is currently the most common strain in Hong Kong, accounting for around 60 per cent of local infections, followed by the H1 subtype at around 35 per cent.

The remaining 5 per cent are infections attributed to influenza B, according to the authorities.