Vaccine shows promise against typhoid in South Asia

[NEW DELHI] A typhoid vaccine shownin trialsto be 79 per cent effective, even after two years, is being recommended for use across South Asia, where the food and waterborne disease is widespread.

伤寒是由鼠伤寒细菌引起的一种威胁生命的感染，每年会影响多达2000万人，包括发烧，疲劳，恶心，腹痛，便秘或腹泻。根据World Health Organization (WHO)。

The two existing typhoid vaccines do not provide long-lasting immunity and are not approved for孩子们两岁以下,而the new typhoid conjugate vaccine (TCV) is approved by WHO for use in children from the age of six months.

Results of the study, published November inThe Lancet Global Health,showed that following immunisation with TCV the incidence of typhoid fever dropped to 72 cases per 100,000 person-years (a statistical way to express incidence rate which take into account the number of people in the study and the amount of time each spent in the study) among participants of the study conducted in Lalitpur, Nepal.

In comparison, the incidence of typhoid fever was 342 per 100,000 person-years for participants given a vaccine against bacterial meningitis (MenA vaccine), instead of TCV. Conjugate vaccines combine weak and strong antigens — substances which cause the body to create an immune response — to increase immunity.

在2017年11月至2018年4月之间进行的试验涉及研究人员对10,005名参与者进行单一剂量的伤寒偶联疫苗，并为另外10,005名参与者（9个月至16岁）提供单剂量的MENA。在给定的TCV中，针对13例已确认伤寒病例，到2020年4月，在给定的中东和中东的患者中有62例伤寒病例。

“The protective efficacy of TCV was 83.4 [per cent] in the first 12 months of follow-up compared with 73.0 [per cent] after the first year,” the researchers reported in their research paper. “There were eight deaths, three in the TCV group and five in the MenA group over the study period.”

They said those who developed typhoid fever despite immunisation had fever for a shorter duration, suggesting that the vaccine reduces the severity of the疾病, adding: “TCV will not only prevent typhoid fever, as suggested by our study, but might help control of antimicrobial resistance.”

Although typhoid can be treated with antibiotics, increasing resistance to various antibiotics is making treatment more complicated, says the WHO.

佛巴斯尼亚特, an author of the study and director of the Oxford University Clinical Research Unit,Patan Academy of Health Sciences, Nepal, tellsscidev.netthat “there is now firm evidence to use an effective vaccine against a biblical scourge, typhoid fever”.

“Having a vaccine that is highly efficacious in children will significantly reduce the burden of typhoid,” saysAmesh Adalja, senior scholar at the约翰·霍普金斯卫生安全中心在美国。“These results are promising and show a path forward to better control of typhoid.”

“拥有高效的儿童疫苗将显着减轻伤寒的负担”

Amesh Adalja, Johns Hopkins Center for Health Security

根据研究人员的说法，南亚是伤寒热的闪点，每10万人年的发生率超过500。Basnyat说：“尼泊尔将于2022年第一季度开始针对儿童的伤寒疫苗接种运动 - 印度，孟加拉国和其他人也应该强烈考虑同样地采取行动以帮助其公民。”

阿斯玛·宾特·阿齐兹（Asma Binte Aziz），一名流行病学，公共卫生的研究科学家，International Vaccine Institute (IVI)在首尔，告诉scidev.netthat the trial results suggest that the vaccine (TCV) should be included in routine immunisation in Nepal “as TCV offers proven advantages over earlier typhoid vaccines — smaller dose and longer protection”.

托马斯·威尔兹巴（Thomas Wierzba）, a professor at the威克森林医学院在美国，说：“虽然预防伤寒依赖于饮用品waterand sanitation, it is likely that universal access to these facilities is still many decades away. Because of this situation, the introduction of a safe and efficacious typhoid vaccine for routine immunisation would greatly help typhoid prevention.”

This piece was produced by SciDev.Net’s Asia & Pacific desk.