The 1977 epidemic: the USSR's most secret flu

In the fall of 1977, an outbreak of anomalous flu was recorded
in the USSR from which young people were dying en masse.
Nearly all of the victims were under 25 years of age. The disease
first appeared in the Far East, but soon passed through the
country and went to rage in Europe. In history, this epidemic
is known as the "Russian flu".
The virus first appeared in the spring of 1977 in southern China,
then it got to Japan, and from there to Khabarovsk and Vladivostok,
where the first cases of the disease were recorded in the USSR.
Soviet doctors, unlike the doctors of Maoist China, as in the case
of Covid-19, began to sound the alarm and sent all the information
about the disease to world laboratories. China was actively hiding
the epidemic.
Soviet investigations found that the flu had a mixed structure.
At the first stage, it was formed by two viruses, and by the fall
a third was added to them. Based on the results of etiological
experiments, it was revealed that the "Russian flu" was similar to
the "Spanish flu" that raged after the First World War, and to the
1947 flu epidemic.
The strains of the new influenza were identical in their main
properties to those viruses that Soviet researchers identified in
Antarctic whales in 1975. The whale virus, in turn, was similar
to bird flu. This allowed Soviet scientists to assume that it was
the birds that provoked the "whale flu". The whales ate plankton,
which was heavily flavored with bird feces containing strains of
the disease.
People who were affected by similar types of flu were immune to
the "Russian flu" and did not get sick with it. Therefore, the
disease killed those who did not have antibodies to the H1N1
virus in their bodies. That is, young people born after 1947. Not
caught up in previous outbreaks of influenza. People under 30
made up about 50% of the then Soviet population. But even in
this age group, only about one in five fell ill with the new flu.
Another feature of the "Russian flu" was the relatively painless
course of the disease. 57.8% of patients suffered from it in a mild
form. Only 42.2% of patients had moderate and severe
consequences. In Western Europe, 300,000 people have died from
this flu. How many people died from the disease in the USSR is
unknown, the data is still classified. Globally, this pandemic has
killed 700,000 people.