试验人员将120名18-60岁志愿者随机分配到1.25, 2.5, 5, 或 10微克组，每组人员分别接受两针安慰剂或两针氢氧化铝佐剂全病毒疫苗。56天后发现所有组均产生抗H5N1的中和抗体，但产生免疫反应最好的是两针10微克组。10微克疫苗满足欧盟关于季节性流感疫苗注册的所有要求。局部的疼痛，肿和全身发热是本试验最普遍报告的副反应。但是，疫苗组和对照组报告的副反应发生率无差异。全病毒疫苗副反应发生率与裂解疫苗相似。
EARLY TRIAL SHOWS H5N1 INFLUENZA VACCINE SAFE AND EFFECTIVE IN HUMANS AT LOW DOSES
A vaccine in development against the avian influenza H5N1 virus can produce a safe immune response in healthy people at low doses, according to an Online/Article published today (Thursday September 7, 2006) by The Lancet. Vaccines that are effective at low doses are needed because they would allow more people to be vaccinated in the event of a pandemic.
Vaccines against pandemic influenza are being developed and clinically assessed by several drug companies throughout the world. In a previous trial published by The Lancet, scientists found that 30 micrograms of a vaccine containing part of the H5N1 virus given in two doses with an adjuvant, an additive that can increase effectiveness, produced a good immune response in humans. In the latest trial, Chinese researchers tested the effectiveness of a vaccine that contains a modified version of the whole H5N1 virus plus adjuvant. Vaccines made of whole viruses are known to trigger greater immune responses but are also known to produce more side-effects.
The investigators randomly assigned 120 volunteers aged 18-60 years to receive two doses of a placebo or the whole-virus vaccine at 1.25, 2.5, 5, or 10 microgram doses plus adjuvant aluminium hydroxide. After 56 days they found that all the formulations produced neutralising antibodies against the virus but the best response was seen in the 10 microgram group after two doses. The 10 microgram vaccine met all the European regulatory requirements for the licensing of an influenza vaccine. Pain, swelling, and fever were the most commonly reported side-effects in the trial. However, there was no difference in the frequency of reported side-effects between the vaccine and placebo group. The frequency of side-effects with the whole virus vaccine was also similar to that seen with vaccines made out of virus particles.
Study author Weidong Yin (Sinovac Biotech co. Ltd, Beiing, China) states: “During a pandemic, the demand for influenza vaccines will far outstrip the manufacturing capacity of such vaccines, a situation that has led to WHO encouraging investigation into dose-sparing strategies, including the use of adjuvants and whole-virion vaccine. Our trial suggests that an H5N1 vaccine manufactured and formulated with both of these approaches is well tolerated and immunogenic.”
The authors say trials testing whole-virus H5N1 vaccine with the aluminium hydroxide adjuvant in larger numbers of individuals, including elderly and children, are needed.