Forget Ebola-what about the flu?

Nparkin nparkin at aol.com
Mon Feb 20 02:40:07 EST 1995


I work on influenza in the biotech industry. I hope I am not too late in
responding (I haven't read my newsgroups for a while). Influenza does
change all the time, every year the epidemic is usually characterized by a
dominant immunologically distinct subtype, one for each of the "H3N2",
"H1N1" (both type A), and type B flu strains. This is referred to as
"antigenic drift". It requires annual updating of the vaccine (which is
inactivated and OK but we think we can do better with a live attenuated
vaccine - but that's another matter). As I understand it (I could be
wrong) people who have had the flu in the recent past (several years) can
get infected with a new drifted strain, but will not get deathly ill
unless they are also very old or have other "high risk" conditions, since
they still have a little cross-protective immunity from their previous
infections. The real danger comes from the possibility of "antigenic
shift", which is when a new strain of influenza emerges, such as what
happened in 1918 ("Spanish flu") or 1968 ("Asian flu"), when new genes
encoding new classes of viral surface protiens (HA or NA) enter
circulation (currently believed to be from animal reservoirs). Then nobody
has any protection and are completely susceptible to highly virulent
influenza. Hundreds of thousands (millions, actually) of people died in
1918. There is no way to predict when the next shift will occur, but we
are better prepared with vaccines, incativated or live, that back then.
But it is still a threat, one which government, academic, and industrial
groups are aware of and have contigency plans inplace to combat.
Neil
parkin at aviron.com



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