June 12, 2013 - CHINA - A total of 131 H7N9 avian flu cases have been reported on the Chinese
mainland, including 39 cases resulting in deaths, authorities said. Of
the total, 78 H7N9 patients have been discharged from hospitals after
receiving treatment. The other 14 patients are being treated in
hospitals, reported Xinhua Sunday citing the National Health and Family
Planning Commission. It said the China’s confirmed H7N9 virus cases are
isolated and there has been no sign of human-to-human transmission.
The H7N9 bird flu is a form of the
Influenza virus A.
Detecting the presence of this virus is very difficult because it does
not cause illness in poultry. It is a virulent form of the
H1N1 virus and has a much higher fatality rate.
What is H7N9?
H7N9 bird flu is a form of avian flu that is spread from infected poultry to humans. In the name given to the disease, the
H7 stands for
‘haemaglutinin’ or
HA.
Haemaglutinin is a
glycoprotein found on the surface of the influenza virus. Its main function is to cause the
agglutination (clumping of particles/cells) of blood. HA has
17 different parts and they are labeled as part H1 to H17.
H7 is the type of
haemaglutinin found in this particular virus. The
‘N7’ stands for
Viral neuraminidase, its main function is to help viral DNA enter the patients’ cells and cause infection. Like Haemaglutinin, Viral
neuraminidase also has a number of parts and
N9 is the type of
neuraminidase found in this particular virus.
The H7N9 bird flu is a form of the
Influenzavirus A.
It has been found to commonly infect people who handle poultry infected
with the virus. Detecting this virus is very difficult because it does
not cause illness in poultry. It is a virulent form of the
H1N1 virus and the CDC and WHO
(World Health
Organisatiom) are still looking into its origin, the way it is transmitted and a possible vaccine for the condition.
According to the CDC and WHO the symptoms of mild avian flu are the same as having a viral fever. Symptoms include
sore throat, running nose, muscle aches. Symptoms of infection by a more virulent form of the disease include
severe
respiratory illness, shortness of breath, difficulty breathing,
pneumonia, acute respiratory distress, viral pneumonia, respiratory
failure, multi-organ disease, sometimes accompanied by nausea, abdominal
pain, diarrhea, vomiting, confusion, dizziness etc.
Diagnosis of Avian Flu:
The avian flu cannot be diagnosed by clinical signs and symptoms alone, there are a few basic tests that a physician is
likely to prescribe in
such a case. To perform the test, a lab technician will take a swab of
the throat of the person. This will then be used to culture the organism
in the lab. Tests usually performed are
molecular analysis and culture (growing the organism) analysis. In cases where there is a severe form of the disease, the technician might take a swab from the
lower respiratory tract (a region a little lower in the throat). This again will be analyzed like a normal swab. If the
Influenzavirus A is still not detected, the lab may perform a test called the
viral antigen detection test. This test is used to identify if the patient’s body has produced antigens (fighting cells) against the influenza virus.
In the case of the H7N9 virus, the time of testing is crucial to
accurate diagnosis. A person cannot be tested at the onset of the
disease nor when he/she has fully recovered. This is because the virus
is very rarely detected under such circumstances.
Treatment options:
The CDC and WHO has found that the H7N9 virus is sensitive to
neuramidase inhibitors such as
oseltamivir or zanamivir. These are drugs sold under the commercial name of
Tamiflu. As a precaution doctor says that people should avoid the
indiscrimate use of this drug as it could lead to antibiotic resistance in patients.
Methods of prevention:
The
influenza virus A or the
Avian flu
can be prevented by simple measures. Firstly, people working with
poultry should take adequate protection before handling them. Protective
measures such as wearing a mask and gloves are the best methods. People
should also ensure that they wash their hands well before eating or
touching their face or nose. Currently the CDC has not been able to
pinpoint the exact mode of transmission from human-to-human, but they do
suggest that people should avoid contact with patients infected with
the virus. It is also suggested that patients should be effectively
quarantined during the time of the infection. All in all the H7N9 hasn’t
given the authorities much to worry about till now! -
Health India.
Federal Officials Weigh H7N9 Vaccine Options
Intensive federal deliberations are under way on whether to stockpile a vaccine against the H7N9 flu virus that emerged this spring in China, similar to the government's response to the H5N1 avian flu threat, health officials said today.
In the meantime, vaccine companies are getting ready to produce
enough vaccine for clinical trials, which are slated to begin in August,
according to an update presented before the National Vaccine Advisory
Committee (NVAC), an outside group that assists the US Department of
Health and Human Services (HHS). The meeting was broadcast live on the
Web.
Robin Robinson, PhD, director of the HHS' Biomedical Advanced
Research and Development Authority (BARDA) told the group that over the
past 4 years federal health officials have used an assessment tool to
weigh the risks of novel flu viruses and consider any steps to take with
vaccine and other preparedness activities.
He said the risk weighting for H7N9 virus and the 2009 H1N1 virus
bear some resemblances, with an uncanny similarity in timing. "It's been
4 years and 1 week since I was here to talk about possible pandemic
vaccine efforts [for the 2009 pandemic H1N1 virus]," Robinson said.
When the variant H3N2 virus popped up at state and county fairs in
the United States last summer, federal officials used the same
risk-assessment tool and decided to go only as far as making enough
vaccine for clinical trials, he said. However, if the H7N9 virus evolves
to support sustained human-to-human transmission, the government would
consider a large-scale vaccine campaign.
In stockpiling discussions, federal officials are weighing factors
such as whom to vaccinate, what vaccine platforms to include,
production capacity, timing, and cost, Robinson said. A decision on
stockpiling could come this summer, he added.
Vaccine development details
So far nine different H7N9
seed strains have been developed for vaccine production, and most of
them were made with reverse genetics. However, Robinson said some
classic reassortants are starting to emerge.
Reminiscent of the 2009 H1N1 vaccine, health officials are seeing
disappointing yields of antigen with the vaccine seeds used with
traditional egg-based production methods, Robinson said.
Lower-than-expected antigen yield was one factor that hampered the H1N1
vaccine in its early stages of production. However, he said one change
from 2009 is that scientists can recognize that issue up front.
Officials saw antigen yield increase in 2009 as production of the
pandemic vaccine hit its stride.
A major difference between 2009 and now is that the H7N9 trials
will include two new platforms—cell based and recombinant. "We have more
tools in our toolbox," he said.
In October 2012 a 3-year review of existing influenza vaccines
called out gaps in protection, especially in older people. Its
researchers said the newest vaccine technology targets the same part of
the flu virus—the hemagglutinin (HA) head—as traditional vaccines and
aren't likely to yield substantial efficacy improvements.
The group, from the University of Minnesota's Center for
Infectious Disease Research and Policy, publisher of CIDRAP News
concluded that new approaches are needed, such as vaccines that target
the HA stalk, and that major national and global efforts are required to
overcome significant challenges in producing a game-changing flu
vaccine.
Progress on the recombinant vaccines is running a little ahead of
the traditional vaccines, with better antigen yields so far, Robinson
said, predicting that the first vaccine lots will be released in July,
with the first clinical trials to launch in August. "That may sound
familiar, because that's when we started testing the H1N1 vaccine,"
Robinson said.
BARDA has been supporting an H7N1 vaccine candidate made by
GlaxoSmithKline, and trials of that vaccine will launch in early July,
he said. Given that the vaccine is a "cousin" of the H7N9 vaccine, those
trials are likely to produce interesting findings shortly in advance of
the H7N9 results. The H7N1 virus is one of a handful of flu strains
considered to have pandemic potential.
The Food and Drug Administration (FDA) has already started work on
the potency assay reagents that will be used to assess the candidate
H7N9 vaccines, Robinson said. He added that at least two alternate
potency assays are being assessed. A federal countermeasure assessment
and a White House review of the 2009 H1N1 vaccine campaign both
suggested that new vaccine potency assays might be one way to shorten
pandemic vaccine production timelines.
H7N9 challenges ahead
Looking ahead to the H7N9 trials,
federal officials and researchers will have some daunting challenges.
"Historically, H7 vaccines haven't provided a very rosy picture for us,"
Robinson said. "We have our work cut out for us."
Earlier trials of inactivated subunit H7 vaccines with and without
adjuvant haven't shown a strong immune response, he said. "That is
alarming."
Robinson said live-attenuated influenza vaccine (LAIV) trials with
H7 strains have shown modest immunity, for what can actually be
measured. More recently, studies have hinted that priming with LAIV H7
vaccine followed by vaccination with inactivated vaccine may produce a
robust response, he told the group.
Last month, CIDRAP Director Michael T. Osterholm, PhD, MPH, and colleagues said in a Journal of the American Medical Association (JAMA)
commentary that if the H7N9 evolves into a pandemic strain, the world
is unlikely to make enough of the vaccine in time to dampen the impact.
Besides the limited effectiveness of H7 vaccines tested so far, the
global public health community remains unprepared, they wrote, despite
added vaccination production capacity.
The group projected that at the 90-microgram (mcg) dose used for
the H5N1 vaccine, the global capacity for H7N9 vaccine would be 757
million doses, less than 15% of the global need.
Robinson said researchers don't know what dosage is needed, but
given the lack of population immunity to H7 strains, the amount of
antigen in a dose of unadjuvanted vaccine might require as much as 90
mcg, as with the H5N1 version. He predicted that two doses of H7N9
vaccine would be needed. With that estimate, it would take 18 months to
provide enough vaccine for everyone, with the cost likely to be
prohibitive, he said.
As federal officials weigh different H7N9 vaccine scenarios, one
decision they have made is that its production should not delay seasonal
flu vaccine manufacturing, he said.
The combination of factors involves may increase the possibility
that a dose-sparing adjuvanted vaccine would be needed in an H7N9
immunization campaign, Robinson said. Unlike in many other parts of the
world, adjuvants haven't been used in US flu vaccines, and their
inclusion in a pandemic vaccine would create challenges in pitching it
to a public that is unfamiliar with the vaccine boosters.
NVAC members asked federal health officials about H7N9 vaccine
efforts under way in China. During the 2009 H1N1 pandemic, China was the
first country to bring a vaccine to market. Robinson said several
different companies in China are developing H7N9 vaccines. "They are
probably at the same point we are," he said. -
CIDRAP.
