Get access

Vaccines for preventing anthrax

  • Review
  • Intervention

Authors


Abstract

Background

Anthrax is a bacterial zoonosis that occasionally causes human disease and is potentially fatal. Anthrax vaccines include a live-attenuated vaccine, an alum-precipitated cell-free filtrate vaccine, and a recombinant protein vaccine.

Objectives

To evaluate the effectiveness, immunogenicity, and safety of vaccines for preventing anthrax.

Search methods

We searched the following databases (November 2008): Cochrane Infectious Diseases Group Specialized Register; CENTRAL (The Cochrane Library 2008, Issue 4); MEDLINE; EMBASE; LILACS; and mRCT. We also searched reference lists.

Selection criteria

We included randomized controlled trials (RCTs) of individuals and cluster-RCTs comparing anthrax vaccine with placebo, other (non-anthrax) vaccines, or no intervention; or comparing administration routes or treatment regimens of anthrax vaccine.

Data collection and analysis

Two authors independently considered trial eligibility, assessed risk of bias, and extracted data. We presented cases of anthrax and seroconversion rates using risk ratios (RR) and 95% confidence intervals (CI). We summarized immunoglobulin G (IgG) concentrations using geometric means. We carried out a sensitivity analysis to investigate the effect of clustering on the results from one cluster-RCT. No meta-analysis was undertaken.

Main results

One cluster-RCT (with 157,259 participants) and four RCTs of individuals (1917 participants) met the inclusion criteria. The cluster-RCT from the former USSR showed that, compared with no vaccine, a live-attenuated vaccine (called STI) protected against clinical anthrax whether given by a needleless device (RR 0.16; 102,737 participants, 154 clusters) or the scarification method (RR 0.25; 104,496 participants, 151 clusters). Confidence intervals were statistically significant in unadjusted calculations, but when a small amount of association within clusters was assumed, the differences were not statistically significant. The four RCTs (of individuals) of inactivated vaccines (anthrax vaccine absorbed and recombinant protective antigen) showed a dose response relationship for the anti-protective antigen IgG antibody titre. Intramuscular administration was associated with fewer injection site reactions than subcutaneous injection, and injection site reaction rates were lower when the dosage interval was longer.

Authors' conclusions

One cluster-RCT provides limited evidence that a live-attenuated vaccine is effective in preventing cutaneous anthrax. Vaccines based on anthrax antigens are immunogenic in most vaccinees with few adverse events or reactions. Ongoing randomized controlled trials are investigating the immunogenicity and safety of anthrax vaccines.  

摘要

背景

用以預防炭疽之疫苗

炭疽是一種細菌性之動物傳染病,其偶爾會造成人類疾病,且具有潛在致命性。炭疽疫苗包括活菌減毒疫苗、鋁沈澱性無細胞濾液疫苗、以及基因重組蛋白疫苗。

目標

評估疫苗對於預防炭疽之有效性、致免疫性、及安全性。

搜尋策略

我們搜尋以下資料庫(2008年11月): Cochrane Infectious Diseases Group Specialized Register、CENTRAL (Cochrane Library 2008, Issue 4) 、MEDLINE、EMBASE、LILACS以及mRCT。我們也搜尋參考資料清單.

選擇標準

茲收錄比較炭疽疫苗與安慰劑、其他(非炭疽)疫苗、或無措施;或是比較炭疽疫苗之投與途徑或療程的個體及聚類RCTs之隨機對照試驗(randomised controlled trials;RCTs)。

資料收集與分析

由2名作者分別考慮試驗適用性,評估偏差風險,並摘錄數據。使用風險比(risk ratio;RR)及95%信賴區間(confidence interval;CI)表示炭疽病例及血清轉換率。使用幾何平均數摘述免疫球蛋白G (immunoglobulin G;IgG)之濃度。茲進行敏感性分析以檢測某1項聚類RCT對於整體結果是否有聚類影響。本研究並未進行整合分析。

主要結論

共有1項聚類RCT (157,259名參與者)及4項個體之RCTs (1917名參與者)符合收錄標準。該取自前蘇聯之聚類RCT顯示,相較於無疫苗之情形,活菌減毒疫苗(稱為STI)可保護對抗臨床炭疽,不論是由無針裝置給與(RR 0.16; 102,737名參與者,154聚類)或是由劃痕法給與(RR 0.25; 104,496名參與者,151聚類)。在未經調整之計算中,信賴區間具有統計顯著性,但在假設聚類中具有小量之相關性時,該等差異則不具統計顯著性。該等有關滅活疫苗(吸附性炭疽疫苗及重組保護性抗原)之4項RCTs (針對個體)顯示,抗保護性抗原IgG抗體之效價具有劑量反應關係。肌內注射在注射位置較皮下注射具有較少之反應,且在投劑間隔較長時注射位置反應率亦較低。

作者結論

唯一1項聚類RCT僅提供有限之證據,說明活菌減毒疫苗可有效預防皮膚型炭疽。以炭疽抗原為基礎之疫苗在大部分之疫苗接種者體內皆具有致免疫性且少發生不良作用及反應。進行中之隨機對照試驗仍在研究炭疽疫苗之致免疫性及安全性。

翻譯人

此翻譯計畫由臺灣國家衛生研究院(National Health Research Institutes, Taiwan)統籌。

總結

炭疽通常是一種影響動物之細菌感染。炭疽不常見於人類,但其可經由皮膚之破口、從受到污染之食物、以及經由吸入細菌而感染。人類之炭疽通常極為嚴重且可造成高死亡率。茲已研發出各種不同類型之炭疽疫苗,以保護可能暴露在該感染之風險下者。本回顧之作者希望評估疫苗對於預防炭疽的效益及害處。其共尋找出4項近期之較小型個體隨機對照試驗以及1項包括超過150,000名參與者之較早期大型聚類隨機對照試驗。該聚類試驗僅提供有限之證據,說明以一種無法造成疾病之活體炭疽菌株作為基礎的疫苗可有效預防皮膚型炭疽。在該等較小型試驗中檢驗之較近期疫苗類型(其亦係以炭疽菌之無活性組成份作為基礎)似乎具有極少之不良作用並可激發良好之免疫反應。目前仍有測試此等較新疫苗之數項隨機對照試驗正在進行。其將可提供進一步之資訊,說明各種可用於具有炭疽接觸風險者之不同疫苗療劑的致免疫性及安全性。

Plain language summary

Vaccines for preventing anthrax

Anthrax is a bacterial infection that usually affects animals. Anthrax is not common in humans, but it can be acquired through breaks in the skin, from contaminated food, and through inhalation of bacteria. Human anthrax is often serious and can cause high rates of death. Various types of anthrax vaccines have been developed to protect those who may be exposed to the infection. The authors of this review wanted to evaluate the benefits and harms of vaccines for preventing anthrax. They identified four recent smaller randomized controlled trials of individuals and an older large cluster-randomized controlled trial with over 150,000 participants. The cluster trial provided limited evidence that a vaccine, based on a strain of live anthrax organisms incapable of causing disease, was effective in preventing cutaneous anthrax. More recent types of vaccines tested in the smaller trials, also based on inactivated components of the anthrax bacterium, appear to have few adverse events and to stimulate a good immune response. Several randomized controlled trials testing these newer vaccines are currently in progress. They will provide further information on the immunogenicity and safety of different vaccine regimens to be used for people at risk of anthrax exposure.

Get access to the full text of this article