The 1977 Russian flu was an
influenzapandemic that was first reported by the
Soviet Union in 1977 and lasted until 1979.[1][2] The outbreak in
northern China started in May 1977, slightly earlier than that in the Soviet Union.[3][4] The pandemic mostly affected a population younger than 25 or 26 years of age,[1][5][6] and was described as mild.[6] It was caused by an
H1N1 flu strain which highly resembled a virus strain circulating worldwide from 1946 to 1957.[1][2][5][6] Genetic analysis and several unusual characteristics of the 1977 Russian flu have prompted many researchers to say that the virus was released to the public through a laboratory accident,[4][5][7][8][9][10] or resulted from a
live-vaccinetrial escape.[5][11]
History of outbreak
In May 1977, an
outbreak of flu took place in northern
China including
Liaoning,
Jilin and
Tianjin.[3][5][12][13] The strain was isolated and determined by Chinese researchers to be
H1N1, which mostly affected students in middle and primary schools who lacked immunity to H1N1 virus.[3] Clinical symptoms were relatively mild.[3] Other areas in
mainland China and
British Hong Kong were also affected in the following months.[3][8]
In the same year, the H1N1 strain was detected in
Siberia shortly after the outbreak in China, and then spread rapidly across the
Soviet Union, which was the first country to report the outbreak to the
World Health Organization (the
People's Republic of China was not a member of WHO until 1981[14]).[1][4][5][6] Therefore, the pandemic was named "Russian flu".[15]
In 1977, the Russian flu hit the
United Kingdom.[16] The virus reached the
United States in January 1978.[6][12] The first outbreak in the U.S. was reported in a high school in
Cheyenne, where the
clinical attack rate was more than 70% but involved solely students.[2][6] Even though infections were seen in schools and military bases throughout the U.S., there were few reports of infection in people older than 26, and the death rate in affected individuals was low.[2][6]
Since late 1977, the H1N1 strain has begun to co-circulate with the
H3N2 strain in humans, as
seasonal flu.[1][3][15]
Virology
There have been various
H1N1 strains.[5] The 1918 Spanish flu was caused by an H1N1 strain, and H1N1 strains afterwards became
endemic and circulated around the world until 1957, when they all but vanished. (There were some isolated reports of other H1N1 strains such as the one in the early 1960s.[17]) H1N1 reappeared in 1977 and the strain of the Russian flu was almost identical to one that had been isolated in 1950.[1][2][3][4][5][6][11] This feature of the 1977 strain has been interpreted as pointing towards an
anthropogenic origin of the virus, and the pandemic is the only documented human epidemic believed to result from research activity.[5][18][19][20]
It has been suggested by many researchers that the virus leaked to the public from a laboratory accident.[4][8][21][22] The virus may have escaped from a lab attempting to prepare an attenuated H1N1 vaccine in response to
the US swine flu pandemic alert of 1976.[23] The
World Health Organization, however, ruled out a laboratory origin in 1978 after discussions with researchers in the Soviet Union and China: their report stated that "the laboratories concerned either had never kept H1N1 virus or had not worked with it for a long time".[3][5]
Others have suggested that it resulted from a
vaccine trial or
challenge.[5][20] The multiple source locations of outbreak made a single-laboratory origin less likely than a vaccine accident.[5] Virologist
Peter Palese claims the outbreak was the "result of vaccine trials in the
Far East involving the challenge of several thousand military recruits with live H1N1," according to personal communication with virologist
Chi-Ming Chu.[11]
The idea that the virus may have been a deliberately-deployed bioweapon appears unlikely and inconsistent with Soviet biological weapon research at the time.[5]
In February 2021, some researchers suggested that this virus might have been engineered via
serial passage,[24] referring to the original study of 1981.[25]
Clinical statistics
The Russian flu was relatively benign. In 1977, Chinese researchers found uneven
attack rates among different groups of students, as well as many mild and
asymptomatic infections.[3] In the
United States, some researchers estimate the influenza mortality rate (not the
infection fatality rate or the
case fatality rate) around 5 in every 100,000 population, less than that of the typical
seasonal influenza (~6 in every 100,000 population).[5][26] Most of the infected people were under the age of 26 or 25,[1][5][6] presumably because older people retained immunity from exposure to previous H1N1 strains.[11]
Contradicting these descriptions, one review article proposed that 700,000 people died due to the Russian flu pandemic worldwide and that the virus was "Identical with “Spanish flu” virus".[27]
^Klimov, AI; Ghendon, YZ (1981). "Genome analysis of H1N1 influenza virus strains isolated in the U.S.S.R. during an epidemic in 1961-1962". Archives of Virology. 70 (3): 225–32.
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10.1007/BF01315129.
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^Imperiale, Michael J.; Howard, Don; Casadevall, Arturo (2018-08-28). "The Silver Lining in Gain-of-Function Experiments with Pathogens of Pandemic Potential". Influenza Virus. Methods in Molecular Biology. Vol. 1836. pp. 575–587.
doi:
10.1007/978-1-4939-8678-1_28.
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