H3N2v: Specific vaccine is needed to fight novel swine-origin influenza A (h3N2v)

By Syed Akbar
Hyderabad:  As more cases of novel swine-origin influenza A
(H3N2 v) infections emerge from many pockets of the USA, researchers
warn that a specific vaccine is required to fight the problem in case
the virus takes the shape of an epidemic.

Though there is no immediate cause of concern for India, the threat of
H3N2 v spread in the country persists given the largescale movement of
people between the two countries. The Indian Institute of Virology,
the only national virology research facility in the country, has not
yet initiated any concrete measures to educate people about this new
emerging threat. The Pune-based NIV has a specialised influenza
research facility, but it has limited its study so far to novel human
influenza A (H1N1) and bird influenza viruses.

The virus, H3N2 v, carries a gene from the pandemic novel human
influenza virus (H1N1) that first created a major health panic in
2009, and continues to cause sporadic infections in India.
Incidentally, the pandemic H1N1 virus spread in the country from USA.
The Indian Council of Medical Research (ICMR) too is yet to take up
research on the emerging virological pattern of the novel swine-origin
influenza, even as the US researchers are a step ahead in finding a
new vaccine.

What is worrying is that this virus, which originally circulated in
pigs, has acquired the capability to infect people. “Children and
middle-aged persons do not have immunity to the virus. The infection
rate is also high among these groups,” warns the Centres for Disease
Control and Prevention (CDC) of the USA.

Meanwhile, researchers from Canada have found that a substantial
proportion of adolescents and young adults have cross-reactive
antibody against H3N2v. But children and older adults showed broad
susceptibility. “A specific vaccine would be needed in the event H3N2
v establishes epidemic spread,” says a research study published in the
Journal of Infectious Diseases.

According to the study, the seasonal flu vaccines used in the past two
seasons did not improve the ability to mount an immune response to
H3N2 v. A little over 1100 people, who had undergone vaccination for
novel human influenza virus, participated in the serological tests
conducted by Canadian researchers. Children below five years did not
show sero protection, which means they are vulnerable to this new
strain of zoonotic virus.

"Our serologic findings suggest substantial protection against H3N2 v
in late adolescence and young adulthood, but broad susceptibility in
children and older adults," the researchers said.