Warning over 6-month time lag to develop pandemic flu vaccine
11 May 2009
Research from the University of Leicester and University Hospitals of
Leicester NHS Trust warns of a six-month time lag before effective
vaccines can be manufactured in the event of a pandemic flu outbreak.
By that time, the first wave of pandemic flu may be over before
people are vaccinated, says Dr Iain Stephenson, Consultant in Infectious
Diseases at the Leicester Royal Infirmary and a Clinical Senior Lecturer
at the University of Leicester.
In his paper published in Proceedings of the National Academy of
Sciences of the USA Dr Stephenson makes the first case for a
pre-pandemic vaccine to mitigate the worst effects of pandemic flu.
He said: “This study is the first to show an effective pre-pandemic
vaccine approach. This means that we could vaccinate people potentially
many years before a pandemic, to generate memory cells that are long
lasting and can be rapidly boosted by a single dose of vaccine when
Dr Stephenson, of the Department of Infection, Immunity and
Inflammation at the University of Leicester, said: “If an influenza
pandemic occurs, vaccination will to be the main way to protect the
population. The major current threat seems to be from avian influenza
H5N1 (bird flu) which has spread rapidly around the world and causes
human infections and deaths.
“Unfortunately, if a pandemic occurs, it will take up to six months
to manufacture effective vaccine, so the first waves of the pandemic may
be over before people are vaccinated. Furthermore, most people need two
doses of H5 pandemic vaccine to get protection — so this adds a further
“To reduce any delay, we could consider stockpiling vaccine or
immunizing people with vaccine prepared in advance (a so called
‘pre-pandemic vaccine’) to protect them before a future pandemic.
“However, we don’t know which strain of influenza will cause the
pandemic. There are several strains of H5N1 virus, so we can’t be sure
of which virus strain to make pre-pandemic vaccine from. Therefore a
‘pre-pandemic’ vaccine needs to give cross protection to as many H5
strains as possible.”
Dr Stephenson and his team conducted a study comparing the effect of
a single H5 bird flu vaccine dose to people who had been vaccinated with
an H5 vaccine previously with people who had not previously received
vaccine. The aim was the test out the idea of a pre-pandemic vaccination
He said: “We found that those people who received H5 vaccine between
1999 and 2001 responded very well to a single dose of a newer H5
vaccine. They had memory cells that gave a rapid protective response
within 7 days of the repeat vaccine. Also the response was very broad
and able to protect against all known strains of H5N1 virus.
“In contrast, those people who had not been previously vaccinated
with H5 vaccine, behaved as we had expected. They required 2 doses of
vaccine and got good antibody responses up to 6 weeks after the first
Dr Stephenson added that this was the first study to show an
effective pre-pandemic vaccine approach.
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