All necessary vaccines for H3N2 influenza available in Armenia

YEREVAN, NOVEMBER 8, ARMENPRESS. Healthcare officials do not exclude the possibility of Influenza H3N2 (Hong Kong flu) penetrating to Armenia, however they urge not to panic because the country has necessary vaccines.

“The virus’s strains are airborne, and depending on conditions, weather, they become active. The type B virus was predominant in 2014-2015, H1N1 in 2015-2016, this time it may be the H3N2”, Liana Torosyan, a healthcare ministry official told ARMENPRESS.

Torosyan says the virus strains are not present in Armenia.

In accordance to the recommendations of the World Health Organization, vaccination will be carried out among vulnerable groups (chronically ill, elderly, medical personnel). Upon completion of vaccination of the groups, anyone willing to take the vaccine will also be vaccinated. Vaccinations will be carried out until mid November.

Influenza A virus subtype H3N2(A/H3N2) is a subtype ofviruses that causesinfluenza(flu). H3N2Virusescan infect birds and mammals. In birds, humans, andpigs, the virus hasmutatedinto many strains. H3N2 is increasingly abundant inseasonal influenza, which kills an estimated 36,000 people in the United States each year.

H3N2 is a subtype of the viralgenusInfluenzavirus A, which is an important cause ofhuman influenza. Its name derives from the forms of the two kinds ofproteinson the surface of its coat,hemagglutinin(H) andneuraminidase(N). Byreassortment, H3N2 exchanges genes for internal proteins with other influenza subtypes.

Seasonal H3N2flu is ahuman flufrom H3N2 that is slightly different from one of last year'sflu seasonH3N2 variants. Seasonal influenza viruses flow out of overlapping epidemics in East andSoutheast Asia, then trickle around the globe before dying off. Identifying the source of the viruses allows global health officials to better predict which viruses are most likely to cause the most disease over the next year. An analysis of 13,000 samples of influenza A/H3N2 virus that were collected across six continents from 2002 to 2007 by the WHO'sGlobal Influenza Surveillance Networkshowed the newly emerging strains of H3N2 appeared in East and Southeast Asian countries about six to 9 months earlier than anywhere else. The strains generally reachedAustraliaandNew Zealandnext, followed byNorth Americaand Europe. The new variants typically reached South America after an additional six to 9 months, the group reported.

TheHong Kong Fluwas acategory 2flu pandemiccaused by a strain of H3N2 descended fromH2N2byantigenic shift, in which genes from multiple subtypes reassorted to form a new virus. This pandemic of 1968 and 1969 killed an estimated one million people worldwide.The pandemic infected an estimated 500,000 Hong Kong residents, 15% of the population, with a low death rateIn the United States, about 33,800 people died.

Both the H2N2 and H3N2pandemic flustrains contained genes from avian influenza viruses. The new subtypes arose in pigs coinfected with avian and human viruses and were soon transferred to humans. Swine were considered the original "intermediate host" for influenza, because they supported reassortment of divergent subtypes. However, other hosts appear capable of similar coinfection (e.g., many poultry species), and direct transmission of avian viruses to humans is possible. H1N1 may have been transmitted directly from birds to humans (Belshe 2005).

The Hong Kong flu strain shared internal genes and theneuraminidasewith the 1957Asian flu(H2N2). Accumulated antibodies to the neuraminidase or internal proteins may have resulted in much fewer casualties than mostpandemics. However, cross-immunity within and between subtypes of influenza is poorly understood.

The Hong Kong flu was the first known outbreak of the H3N2 strain, though there is serologic evidence of H3N? infections in the late 19th century. The first record of the outbreak in Hong Kong appeared on 13 July 1968 in an area with a density of about 500 people per acre in an urban setting. The outbreak reached maximum intensity in two weeks, lasting six weeks in total. The virus was isolated inQueen Mary Hospital. Flu symptoms lasted four to five days.

By July 1968, extensive outbreaks were reported inVietnamandSingapore. By September 1968, it reachedIndia, thePhilippines, northernAustraliaand Europe. That same month, the virus enteredCaliforniafrom returningVietnam War troops. It reachedJapan, Africa and South America in 1969.

"Three strains of Hong Kong influenza virus isolated from humans were compared with a strain isolated from a calf for their ability to cause disease in calves. One of the human strains. A/Aichi/2/68, was detected for five days in a calf, but all three failed to cause signs of disease. Strain A/cal/Duschanbe/55/71 could be detected for seven days and caused an influenza-like illness in calves.