Types A and B
A has subtypes and animal hosts; B is mainly a human seasonal actor.
Identity is a family of RNA viruses named for their HA and NA surfaces when they are type A.
Most winters are drift. A handful of years in a century are shift and global shock.
Traits
HA and NA
These proteins are what antibodies often see and what vaccine updates chase.
Segmented genome
Eight pieces allow reassortment if two A viruses meet in one host.
Winter seasonality
In temperate countries, indoor crowding and humidity patterns favor winter waves.
Pandemic potential
A novel HA in a transmissible package can sweep a world with little prior immunity.
Not stomach flu
Gastrointestinal outbreaks are usually other viruses. Influenza is mainly respiratory.
A nickname in the news is a surveillance file, not a cartoon villain.
Keep exploring
More in Encounters
Tuberculosis
An airborne bacillus of latency and long care — programmes and air, not a drug recipe.
Familiarity 70Escherichia coli
Usually a gut resident; a minority of STEC pathotypes drive foodborne headlines.
Familiarity 82Staphylococcus aureus
A common skin neighbor and a resistance story called MRSA — not scare porn.
Familiarity 78Norovirus
A very-low-dose gut virus of schools and ships — soap and bleach surfaces, not alcohol-gel faith.
Familiarity 80Helicobacter pylori
A gastric spiral that rewrote the ulcer textbook — Nobel 2005, Korea's high historic prevalence, no recipes.
Familiarity 68