Here are some lesser-known facts about influenza that you should know:
The origin of the word “influenza”
The word “influenza” doesn’t come from a scientific lab. Its roots are in medieval Italian, specifically from the 15th century. Back then, outbreaks of what we now know as the flu were often blamed on astrological forces or the “influence” of the stars. The Italian phrase “influenza di stelle” literally means “influence of the stars.” Over time, this was shortened to “influenza” or simply “flu” to describe the widespread illness. This historical origin highlights how mysterious infectious diseases were before the discovery of germ theory.
Flu is contagious before and after symptoms
One reason the flu spreads so easily is that you can transmit the virus even before you feel sick.
Typically, people are contagious starting one day before symptoms appear. This means you can unknowingly spread the virus just by going about your daily routine. What’s more, contagiousness usually lasts for five to seven days after symptoms begin, and sometimes even longer, especially in young children or those with weaker immune systems. This extended period of contagiousness, combined with the pre-symptomatic phase, makes it incredibly challenging to contain influenza outbreaks.
The virus is constantly changing, leading to many subtypes
The influenza virus is a master of disguise, constantly mutating and evolving. There are three types that infect humans: A, B, and C, with influenza A and B being the main types that cause seasonal epidemics. Within these types, there are many subtypes and strains, each with slightly different genetic makeups. For example, influenza A viruses are categorised into subtypes like H1N1 or H3N2 based on their surface proteins.
This constant genetic change means that immunity you get from a previous infection or vaccination might not protect you from a newly emerged strain. This is why the annual flu vaccination is crucial. Each year, flu vaccines are formulated according to the circulating influenza viruses. Without the yearly vaccination, your immune system wouldn’t be ready for the ever-changing viral landscape.
The virus can survive on hard surfaces
Influenza viruses are surprisingly resilient outside the human body, especially on hard surfaces. Studies show that the flu virus can survive for up to 24 to 48 hours on non-porous surfaces like doorknobs, countertops, tables, and phones. However, on softer, porous surfaces such as tissues or clothes, the virus survives for a shorter period, typically around 8-12 hours. This ability to linger on surfaces emphasises the importance of frequent handwashing and regularly disinfecting commonly touched objects, especially during flu season, to reduce indirect transmission.
Vitamin C does not protect from flu
Despite popular belief and widespread use, high doses of Vitamin C do not prevent you from getting the flu or significantly reduce its duration or severity. While Vitamin C is vital for overall health and immune function, clinical studies have consistently failed to show a direct protective effect against influenza infection in the general population. Some research suggests it might slightly shorten the duration of the common cold in some people, but this effect is often minor and doesn’t apply to the flu.
Get your annual flu vaccination
Given the continuous evolution of the influenza virus, its ability to spread before symptoms appear, and its surprising persistence on surfaces, annual influenza vaccination is the single most effective way to protect yourself and your community from the flu. Vaccination helps your immune system recognise and fight off the most common strains expected in each season. This significantly reduces your risk of infection, severe illness, hospitalisation, and even death. It also contributes to “herd immunity,” protecting those who can’t be vaccinated. Make annual flu vaccination a priority for your health!
Reference:
- https://www.medicinenet.com/what_are_interesting_facts_about_the_flu/article.htm
- https://www.cdc.gov/flu/about/viruses-types.html
Hemilä, H., Chalker, E. Vitamin C reduces the severity of common colds: a meta-analysis. BMC Public Health 23, 2468 (2023).
