The Hong Kong flu is a global epidemic that raged between the summer of 1968 and the beginning of 1970. It was then the third influenza pandemic to occur in the 30th century. It was responsible for one to four million deaths worldwide, including 000 to 35 in France and more than 000 in the United States. The A (H50N000) virus, responsible for this pandemic, is still in circulation today and is considered a strain of the seasonal flu.

Now largely forgotten, the Hong Kong flu is a global epidemic that raged for three years between the summer of 1968 and the beginning of 1970.

This is the third influenza pandemic to occur in the 1956th century. The Hong Kong flu followed the pandemics of 58-1918 – called the Asian flu – and 19-1968 – called the Spanish flu. The 3 pandemic was triggered by the emergence of an influenza virus type A subtype H2NXNUMX.

It was responsible for one to four million deaths worldwide, including 30 to 000 in France and more than 35 in the United States, much less than the Spanish flu, which had caused between 000 and 50 million people. dead. Half of the deaths are to be deplored in people under the age of 000 – unlike the current Covid-25 pandemic.

Contrary to its name, the Hong Kong influenza originated in China in July 1968 and spread throughout the world until 1969-70. It bears the misleading name of “Hong Kong flu” because the virus manifested itself in a very virulent way in this British colony in mid-July 68. 

The A (H3N2) virus that caused the 1968 pandemic is still in circulation today. It is considered a strain of the seasonal flu.

For 10 years, the A (H1N1) virus, responsible for the 1918 pandemic, was responsible for seasonal influenza until the 1968 pandemic when the A (H3N2) virus took its place. In 1977, a re-emergence of the A (H1N1) virus was observed – Russian influenza. Since that date, the A (H1N1) and A (H3N2) viruses have been circulating regularly during seasonal flu. During the 2018-2019 epidemic period, the A (H3N2) and A (H1N1) viruses circulated at the same time, representing respectively 64,9% and 33,6% of influenza viruses identified in mainland France.

In the 1990s, a virus closely related to the Hong Kong influenza virus was isolated from pigs. Scientists suspect that the human A (H3N2) virus has spread to pigs: infected animals may show symptoms of swine flu.

The Hong Kong influenza virus is believed to have originated from a strain of that which caused the Asian influenza pandemic of 1956: influenza A of the H2N2 subtype gave rise to H3N2 by a process of genetic mutation on the external surface virus to produce the new H3 antigen. Because the new virus retained the neuraminidase N2 antigen, people who had been exposed to the 1956 virus apparently retained immune protection against the 1968 virus.

Symptoms

The symptoms of the Hong Kong flu are typical of the flu:

• High fever with chills;
• Migraines;
• Myalgia: muscle pain and weakness;
• Arthralgia: joint pain;
• Asthenia: weakening of the organism, physical fatigue;
• Cough.

These symptoms usually lasted for four to six days.

The Hong Kong flu has caused more or less serious illnesses in different populations around the globe. While the disease was widespread and affected only a small number of people in Japan, it was widespread and fatal in the United States.

Complications

The complications related to the Hong Kong flu are as follows:

• Broncho-pulmonary bacterial superinfections;
• Severe lung disease;
• Decompensation of cardiac or respiratory failure;
• Encephalitis;
• Myocardite ;
• Pericarditis;

Although a vaccine was developed against the Hong Kong influenza virus, it did not become available until after the peak of the pandemic in many countries. On the other hand, this vaccine has enabled the rise of influenza vaccines: a strain of the Hong Kong influenza virus also incorporates the composition of current vaccines.

The Hong Kong flu and Covid-19 have in common the fact that they are viral pandemics. Moreover, the two viruses are RNA viruses, which implies the possibility of mutations for both. Finally, the Hong Kong influenza virus, like that of Covid-19, SARS-CoV-2, affected France in two waves: the first during the winter of 1968-1969, and the second the following winter.