Un­pre­dictable virus means no one can prom­ise last year’s flu sea­son won’t hap­pen again

Modern Healthcare - - PUBLIC HEALTH - By Steven Ross John­son

Af­ter last year’s dev­as­tat­ing flu sea­son, which hos­pi­tal­ized the largest num­ber of se­niors in the U.S. ever recorded, public health of­fi­cials have had to as­sure providers that the flu vac­cines they’re get­ting right about now will work.

At a news con­fer­ence in Septem­ber, Dr. Thomas Frieden, di­rec­tor of the Cen­ters for Dis­ease Con­trol and Preven­tion, ad­mit­ted that last fall and win­ter were a “bad year for flu.” Then he rolled up his sleeve for a shot.

“So far, the strains in this year’s vac­cine seem likely to match,” Frieden said.

But ex­perts point out that last year’s sit­u­a­tion could hap­pen again, be­cause the virus is un­pre­dictable and vac­cines take too long to get to the public.

“It hap­pens pe­ri­od­i­cally, it’s not just last year,” said Dr. Robert Daum, a pe­di­atrics pro­fes­sor at the Univer­sity of Chicago. He is also as­sis­tant chair­man of the Illi­nois chap­ter of the Amer­i­can Academy of Pe­di­atrics’ Com­mit­tee on In­fec­tious Dis­eases. “This virus changes and there’s noth­ing you can do about it,” he said.

A mu­ta­tion in the virus’ dom­i­nant strain caused last year’s batch of vac­cines to be only 23% ef­fec­tive. Nor­mally, the rate hovers around 50%.

While some crit­ics quickly used those num­bers to say vac­cines don’t work, more crit­i­cal observers said last sea­son high­lighted a vul­ner­a­bil­ity in the flu vac­cine pro­duc­tion process— it can take months from the time world health lead­ers choose what strains of the virus to use for vac­ci­na­tions to when those drugs be­come avail­able to the public.

Se­lect­ing the right vac­cine to pro­duce each flu sea­son in­volves year- round sur­veil­lance from 142 na­tional in­fluenza cen­ters based in more than 100 coun­tries, ac­cord­ing to the CDC. The World Health Or­ga­ni­za­tion gath­ers lead­ers once in the South­ern Hemi­sphere and again in the North­ern Hemi­sphere to com­pre­hen­sively track the virus. Then, the WHO con- venes in Fe­bru­ary to iden­tify the dom­i­nant virus strain.

The U.S. Food and Drug Ad­min­is­tra­tion next de­cides which flu strains will be used to make vac­cines sold in the U.S. The seven drug­mak­ers con­tracted with the gov­ern­ment can then be­gin de­vel­op­ment to get the vials to doc­tors’ of­fices by early Oc­to­ber.

It’s a 70-year-old process that has proven to be safe and ef­fec­tive but very time­con­sum­ing. Last year’s mu­ta­tion is es­ti­mated to have hap­pened about three months into the pro­duc­tion process. Those sit­u­a­tions high­light where the prob­lems lie.

“We’re com­mit­ting to which flu strains we’re go­ing to make vac­cines for a year in ad­vance of when flu sea­son hits,” said Dr. Christo­pher Gill, as­so­ciate pro­fes­sor of global health at Bos­ton Univer­sity School of Public Health. “So it’s al­ways a guess.” The CDC ad­mits that virus mu­ta­tion poses a chal­lenge. The agency says that’s when it em­pha­sizes other pre­ven­tive and treat­ment tools such as ex­panded ed­u­ca­tion and com­mu­ni­ca­tion ef­forts about in­fluenza an­tivi­ral drugs, like Tam­i­flu, which are a sec­ond line of de­fense to treat the virus. Still, the CDC is stand­ing by the more than 170 mil­lion doses of flu vac­cine ex­pected to be avail­able this fall and win­ter.

To take out some of the guess­work this sea­son, phar­ma­ceu­ti­cal gi­ant Glax­oSmithK­line’s en­tire vac­cine sup­ply will pro­tect against four strains of the virus. Glaxo grows the strains in mil­lions of fer­til­ized chicken eggs.

The egg pro­duc­tion process is the most com­mon, gen­er­at­ing 90% of the U.S. flu vac­cine sup­ply.

But ear­lier this year, another un­ex­pected hur­dle in that pro­duc­tion process emerged. Bird flu killed an es­ti­mated 50 mil­lion birds in 15 states and put vac­cine man­u­fac­tur­ers on high alert, even though they don’t nec­es­sar­ily need eggs that are safe for con­sump­tion.

Still, that de­pen­dence on na­ture has led some drug­mak­ers to look at al­ter­na­tives, such as re­com­bi­nant tech­nol­ogy, which the FDA ap­proved in 2013.

That method uses an­i­mal cells to grow flu viruses, and it could cut down the man­u­fac­tur­ing time from 24 weeks to 16 weeks. It uses a flu virus pro­tein, com­bined with por­tions of another virus grown in in­sect cells. That process re­quires no eggs and takes six to 12 weeks.

Pro­tein Sciences was granted FDA ap­proval in 2013 for its FluBlok vac­cine. FluBlok, which doesn’t re­quire eggs for pro­duc­tion, takes less time to man­u­fac­ture than more con­ven­tional means, but the vac­cine has a shelf life of around six months.

The shorter pro­duc­tion time is im­por­tant, be­cause the more time the man­u­fac­turer has to make a vac­cine, the greater the num­ber of doses will be able to be pro­duced.

In the fu­ture, flu vac­cine pro­duc­ers may be able to de­liver a uni­ver­sal vac­cine, ad­min­is­tered once, that would tar­get parts of the flu virus that don’t mu­tate. But in an in­dus­try that sells in­di­vid­ual pills for $1,000, a $2 shot is not ex­actly an in­cen­tive for in­no­va­tion. In fact, some drug­mak­ers are even get­ting out of the flu vac­cine busi­ness. No­var­tis in Au­gust sold its flu vac­cine arm to Aus­tralian bio­ther­apy com­pany CSL for $275 mil­lion.

AP PHOTO

Pro­tein Sciences, which uses an­i­mal cells to man­u­fac­ture its flu vac­cine, has a shorter pro­duc­tion cy­cle than drug­mak­ers that use eggs.

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