Doc­tor: Obe­sity wors­ens in­fluenza

Bad cases more likely in over­weight peo­ple, flu re­searcher says

San Antonio Express-News (Sunday) - - Metro - By Liz Teitz STAFF WRITER

The flu vac­cine is less ef­fec­tive for obese peo­ple, who are also likely to ex­pe­ri­ence more se­vere flu symptoms, Dr. Stacey Schultz-Cherry said Satur­day, speak­ing at the an­nual Vac­cine De­vel­op­ment Cen­ter of San An­to­nio Con­fer­ence.

Schultz-Cherry, a fac­ulty mem­ber at St. Jude’s Chil­dren’s Re­search Hos­pi­tal in Mem­phis, Tenn., and deputy di­rec­tor of the World Health Or­ga­ni­za­tion Col­lab­o­rat­ing Cen­tre for Stud­ies on the Ecol­ogy of In­fluenza in An­i­mals and Birds, was one of sev­eral keynote speak­ers at the con­fer­ence this week­end, dis­cussing re­search into how obe­sity af­fects the spread of and vac­ci­na­tion against the flu.

De­vel­op­ments to im­prove the ef­fi­cacy of the flu vac­cine are un­der­way, with a goal of in­creas­ing how many strains of the flu virus against which the vac­cine can pro­vide im­mu­nity.

“One thing we need to con­sider is the pop­u­la­tion we’re try­ing to vac­ci­nate,” Schultz-Cherry said. Preg­nant women, young chil­dren, the el­derly and peo­ple whose im­mune sys­tems are com­pro­mised are al­ready con­sid­ered high-risk groups, and obese peo­ple could be an­other, she said.

Dur­ing the 2009 “swine flu” pan­demic, stud­ies sug­gested for the first time that over­weight and obese peo­ple were more likely to de­velop se­vere ill­nesses, she said.

In com­par­ing maps show­ing flu ac­tiv­ity last year and obe­sity rates by state, “the higher the obese pop­u­la­tion, the more likely you are to have hos­pi­tal­iza­tions and ICU stays and even mor­tal­ity,” she said.

Obe­sity is a grow­ing con­cern and has nearly tripled since 1975, ac­cord­ing to WHO, mean­ing there’s a grow­ing pop­u­la­tion of peo­ple who may be more sus­cep­ti­ble to the flu, less able to fight the virus and more likely to spread it to oth­ers for longer.

That’s in part be­cause obe­sity causes chronic low-level in­flam­ma­tion, “so they’re ba­si­cally im­muno-com­pro­mised in many ways,” Schultz-Cherry said.

In re­search look­ing at mice, the obese an­i­mals’ bod­ies were not able to con­trol the virus’s spread the way the bod­ies of lean mice could.

“Obese an­i­mals mount a much lower re­sponse” than leaner mice, she said. The chronic in­flam­ma­tion makes it harder for the body to re­spond, she said, “al­low­ing the virus to take off.”

The mi­cro­biome, or the micro­organ­isms in­side the body, also play a role, she said, which is a sub­ject for fur­ther study.

Obe­sity also makes it harder for the body to clear the virus or the bac­te­rial in­fec­tions that can fol­low, Schultz-Cherry said.

Re­search on fer­rets and stud­ies of hu­mans have also showed sim­i­lar re­sults re­lated to flu sus­cep­ti­bil­ity and trans­mis­sion.

The flu vac­cine causes the body to de­velop an­ti­bod­ies, which pro---

tect against strains of the flu virus. But when vac­ci­nated, the obese mice have been less re­spon­sive and less likely to pro­duce those an­ti­bod­ies, she said.

In study­ing hu­mans, over­weight and obese peo­ple were more likely to lose their an­ti­bod­ies faster af­ter re­ceiv­ing the vac­cine, mak­ing them again more sus­cep­ti­ble to the virus.

That cre­ates “the per­fect storm,” she said. “We have, po­ten­tially, a more sus­cep­ti­ble pop­u­la­tion, higher vi­ral load, more se- vere dis­ease, longer shed and a chang­ing virus. What are we go­ing to do?”

The first an­swer to solv­ing that, she said, is to keep vac­ci­nat­ing.

The risk of hav­ing a heart at­tack or stroke when you get the flu is sig­nif­i­cant for over­weight and obese peo­ple, and the vac­cine re­duces that like­li­hood, even if it’s less ef­fec­tive, she said. “So if for no other rea­son, get your flu vac­cine.”

Fur­ther re­search is on­go­ing, Schultz-Cherry said, and could in­clude look­ing into how age and gen­der fac­tor into sus­cep­ti­bil­ity and trans­mis­sion. “There’s so much we still don’t know,” she said.

The sev­enth an­nual con­fer­ence, which started Fri­day at the Ei­lan Ho­tel, fea­tured keynote speak­ers from across the U.S., as well as stu­dent re­search pre­sen­ta­tions.

The Vac­cine De­vel­op­ment Cen­ter of San An­to­nio opened in 2012, with three goals, Bernard Aru­lanan­dam said. It was cre­ated to in­crease aware­ness of the im­por­tance of vac­cines, fos­ter re­search into vac­cines across sci­en­tific dis­ci­plines and pro­vide op­por­tu­ni­ties for trainees.

Aru­lanan­dam, a pro­fes­sor and vice pres­i­dent for re­search at Univer­sity of Texas at San An­to­nio, is a mem­ber of the con­fer­ence com­mit­tee and a co-di­rec­tor of the cen- ter.

He said shar­ing fac­tual in­for­ma­tion about vac­cines is key to fight­ing pre­ventable dis­eases, such as whoop­ing cough, as well as slow­ing the spread of viruses such as in­fluenza.

“The is­sue of mis­in­for­ma­tion about vac­ci­na­tion has led to out­breaks of child­hood in­fec­tions that can be pre­vented,” Aru­lanan­dam said. Un­der­stand­ing how to make vac­cines more ef­fec­tive and more universal, to im­mu­nize against more strands of viruses, should be a na­tional pri­or­ity, he said.

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