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The H1N1 flu virus (red) bears a disturbing resemblance to the virus strain that caused the 1918 flu pandemic - Source: Reuters -
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Saying the new H1N1 virus is unstoppable, the World Health
Organization gave drug makers a full go-ahead to manufacture
vaccines against the pandemic influenza strain and said healthcare
workers should be the first to get one.
Every country will need to vaccinate citizens against the swine flu
virus and must choose who else would get priority after nurses,
doctors and technicians, said Dr Marie-Paule Kieny, WHO director of
the Initiative for Vaccine Research.
Several reports showed the new virus attacks people differently
than seasonal flu - affecting younger people, the severely obese
and seemingly healthy adults, and causing disease deep in the
lungs.
Kieny briefed reporters on the findings of the WHO's Strategic
Advisory Group of Experts on Immunization, or SAGE.
"The committee recognized that the H1N1 pandemic ... is
unstoppable and therefore that all countries need access to
vaccine," Kieney said.
"The SAGE recognized first that healthcare workers should be
immunized in all countries in order to retain a functional health
system as the virus evolves," she added.
After that, each country should decide who is next in line, based
on the virus's unusual behaviour.
Seasonal influenza is deadly enough - each year it is involved in
250,000 to 500,000 deaths globally.
But most are the elderly or those with some kind of chronic
disease that makes them more vulnerable to flu, such as
asthma.
Elderly advantage
The elderly seem to have some extra immunity to this new H1N1,
which is a mixture of two swine viruses, one of which also contains
genetic material from birds and humans.
It is a very distant cousin of the H1N1 virus that caused the
1918 pandemic that killed 50 million to 100 million people.
A study published in the journal Nature on Monday confirmed that
the blood of people born before 1920 carries antibodies to the 1918
strain, suggesting their immune systems remember a childhood
infection.
The work by Dr Yoshihiro Kawaoka also supports other studies that
this new H1N1 strain does not stay in the nose and throat, as do
most seasonal viruses.
"The H1N1 virus replicates significantly better in the lungs,"
Kawaoka said. Other studies have also shown it can cause
gastrointestinal effects, and that it targets people not usually
thought of as being at high risk.
"Obesity has been observed to be one of the risk factors for more
severe reaction to H1N1" - something never before seen, Kieny
added. It is not clear if obese people may have undiagnosed health
problems that make them susceptible, or if obesity in and of itself
is a risk.
On Friday, a team at the US Centers for Disease Control and
Prevention and the University of Michigan reported that nine out of
10 patients treated in an intensive care unit there were obese.
They also had unusual symptoms such as blood clots in the lungs
and multiple organ failure.
None have recovered and three died.
The CDC estimates at least a million people are infected in the
United States alone and clinics everywhere are advised not to test
each and every patient, so keeping an accurate count of cases will
be impossible.
The United States has documented 211 deaths and WHO counted 429
early last week.
Kieny said WHO would also work to get better viruses for companies
from which to make vaccines.
She said the strains that had been distributed did not grow very
well in chicken eggs - used to make all flu vaccines.
One exception - AstraZeneca's MedImmune unit makes a live virus
vaccine that is squirted up the nose and it is easier to produce,
Kieny said.
WHO said countries should continue with their normal vaccination
programs against seasonal flu.
Kieny said the seasonal H3N2 strain was also very active now in
the southern hemisphere's winter.
Sanofi-Aventis, Novartis, Baxter, Schering-Plough's Nobilon,
GlaxoSmithKline, Solvay, CSL and AstraZeneca's MedImmune are among
those working on flu vaccines.
