Cur­rent vac­cine’s suc­cess rate is lim­ited


Flu shots are made in three main ways but the most com­mon and old­est method, dat­ing back more than 70 years, is us­ing hen’s eggs.

e egg-based pro­duc­tion process be­gins with pri­vate-sec­tor man­u­fac­tur­ers who use can­di­date vac­cine viruses (CVVS) grown in eggs per cur­rent reg­u­la­tory re­quire­ments.

The CVVs are in­jected into fer­til­ized eggs, which are in­cu­bated for sev­eral days to en­able the viruses to repli­cate, to cre­ate large amounts of the u virus, and the fluid con­tain­ing the virus is har­vested from the egg.

The virus is then in­ac­ti­vated (killed) and pu­ri­fied to cre­ate an anti­gen, which in­duces an im­mune re­sponse in the body.

e prob­lem with the cur­rent process, how­ever, is that it takes too long to man­u­fac­ture and dis­trib­ute, has a short shelf life that di­min­ishes monthly and has a rel­a­tively low rate of ef­fec­tive­ness.

e av­er­age rate of ef­fec­tive­ness with ex­ist­ing u shots is about 50 to 60 per cent, said re­searcher Dr. Murdo Fer­gu­son.

But be­cause of the emer­gence of a new u strain last year, that u shot was only about 35-per-cent e ec­tive.

In­fluenza caused about 2,000 deaths in Canada last year and is con­sid­ered a ma­jor killer around the world, which makes the new vac­cine all the more im­por­tant, he said.

And that is in ad­di­tion to count­less oth­ers who sur­vived but who were re­ally sick with the u virus.

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