不活化疫苗施打幾劑的問題--參考資料

蘇少儀

英進行第一波新流感疫苗人體實驗 疫情趨緩
更新日期:2009/08/09 05:02
（中央社記者黃貞貞倫敦7日專電）H1N1新型流感病毒持續在英國蔓延，衛生官員說，第一波新型流感疫苗人體實驗已開始進行，預估最快4週就可以決定施打對象；過去7天確診罹患新型流感人數出現下跌，約3萬人。
新流感疫苗人體實驗在英格蘭列斯特皇家醫院（Leicester Royal Infirmary）進行，共有175人登記參加，由列斯特大學（Leicester University）傳染病學教授史蒂芬生（Dr Iain Stephenson）負責，每位參與者被施打兩劑疫苗，再檢測他們的免疫程度。
新型流感人體實驗的結果，約需要4到6週出爐，衛生部將據此決定疫苗施打的優先對象及範圍。
第一批新型流感疫苗預定9月起開始對一般民眾施打，英國政府考慮對所有年齡5歲到16歲，人數約850萬的學童施打疫苗。
官員預估，到今年底應該有足夠的疫苗供全國半數的人口使用。
英格蘭首席醫療官唐納遜（Liam Donaldson）說，今年夏天新型流感的感染率可能下跌，但到秋天隨著流感季節到來，罹患新流感的人數將大幅增加，出現第二波高峰，政府和民眾都不能掉以輕心，必須提前預防。
衛生保護局（The Health Protection Agency）表示，沒有跡象顯示，新型流感病毒已變種為更致命的病毒，病毒也未對抗病毒藥物產生抗藥性。980807
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New Avian Flu Vaccine Strategy Proposed
Advance shots protect those most exposed in possible pandemic, researchers suggest

By Ed Edelson
HealthDay Reporter

WEDNESDAY, Oct. 8 (HealthDay News) -- People can be protected against a potential avian flu epidemic by getting advance shots of a vaccine that may or may not be effective against the strain causing the epidemic, British researchers suggest.
That apparently daffy strategy is scientifically sound, according to a letter in the Oct. 9 issue of the New England Journal of Medicine, because priming people with an old vaccine would make any new vaccine work faster and better.
A study of 24 people who got a now outdated avian flu vaccine seven years ago shows the strategy would work, said Dr. Iain Stephenson, a senior lecturer in infectious disease at the University of Leicester.
Those people quickly developed flu-fighting antibodies when challenged with the H5 avian flu strain that is regarded as the one most likely to spread from birds to humans and cause an epidemic, Stephenson said.
In June, U.S. researchers reported that they had developed a bird flu vaccine that appeared to be safe and more effective than the one currently approved for human use.
Three-quarters of volunteers produced antibodies against the virus after receiving a second dose of the vaccine, CELVAPAN, made by Baxter, compared with only 45 percent in the currently approved vaccine. Baxter conducted the study.
"If there were to be a pandemic of avian influenza, a vaccine would be the principal means of protecting the public," Stephenson said. "Because most people would be naive to the strain, it would very likely take two doses to produce an immune response. It is very challenging to give two doses."
And while governments have stockpiled vaccines against the H5 strain, "there are two problems," Stephenson said. "Is that vaccine a good match to the pandemic strain? H5 changes, and the emerging strain could be distant to the stockpiled vaccine.
"And considering the speed with which the pandemic might spread, even if you've got a stockpiled vaccine, it would be a challenge to use that vaccine in a two-dose strategy. But if you've got people who have been primed in advance, as we took people who were primed seven years ago, it's possible to give a single low-dose vaccine and show they get a rapid response that is reactive to all known strains."
"It's a very intriguing idea," said Ted Ross, an assistant professor of microbiology at the University of Pittsburgh Center for Vaccine Research.
Ross agreed that the current strategy of giving two flu vaccine shots two weeks apart might not meet the urgent needs of a pandemic. "I believe it is going to take too long in a bird flu pandemic," he said. "Priming the population might be protective against a wide variety of H5 viruses that we know have infected humans already. The broader the protection, the better."
However, there would be financial barriers to a program that would prime a large part of the population along the lines of the Stephenson proposal, Ross noted. "Even with the currently tested vaccine, there currently is no market for vaccinating people widely," he said.
Not everyone need be primed, Stephenson said. "You would be preparing for an event that might never happen, so safety considerations would be paramount," he said. "It is unlikely that the entire population would be covered. It might be proposed to take key personnel, first responders to a pandemic. That is a potential approach that should be considered."
Even then, a single study of 24 people is not enough to prompt such a program, Stephenson noted. "It is important that larger studies be done to confirm the finding," he said.

SOURCES: Iain Stephenson, M.D., senior lecturer, infectious disease, University of Leicester, England; Ted Ross, Ph.D., assistant professor, microbiology, University of Pittsburgh Center for Vaccine Research; Oct. 9, 2008, New England Journal of Medicine


[ 本帖最後由 蘇少儀 於 2009-8-10 09:51 編輯 ]