Experimental Malaria Vaccines Offer Promise

 

Two vaccines² developed by a Maryland company are showing promise in the fight against malaria³.

One vaccine¹ was 100 percent effective in preventing the deadly disease malaria. That is according to the biotech company Sanaria Inc. of Rockville, Maryland that developed the vaccines.

Malaria is a disease caused by parasites⁵ and carried by mosquitoes.

Parasites are organisms that live on or in an organism of another species and feed off it or get protection from it. Mosquitos spread the disease to people by biting on their skin.

The World Health Organization says there are 214 million cases of malaria each year. And the deadly disease kills over 400,000 people a year worldwide.

People who have malaria often have fever, chills, and flu-like illness. Serious complications happen, including death, when the disease is left untreated.

The new vaccines work by preparing the immune system to fight the disease. They do this by introducing live, but weakened, young parasites called sporozoites. They are injected into the body by infected mosquitoes.

Both vaccines target Plasmodium Falciparum, which is the most common and deadly form of the disease.

Successful vaccine study

The more successful of the two trials was carried out in Germany. Different doses, or amounts, of the vaccine were injected into 27 healthy people who volunteered for the study. Another group of 15 was given a placebo⁶, which is a substance given to a patient like a drug, but it has no physical effect on the person.

Eight to 10 weeks after the last vaccine dose, both groups were then exposed to the parasites that carried the malaria.

Stephen Hoffman is chief executive and scientific officer of Sanaria. He says the researchers were surprised by the results from nine of the people who received the highest vaccine dose.

"We got 100% protection against malaria at ten weeks, two-and-a-half weeks after the last dose of the vaccine. That is really beginning to look like something quite extraordinary and that's never been done before."

The results of the study were published in the journal Nature.

Reinfection study

A second trial involving another sporozoite vaccine was carried out in Mali. It tested whether the vaccine prevented reinfection in the people already exposed to malaria.

More than half—66 percent—of those who got the vaccine dose became re-infected with malaria within six months after they were vaccinated⁷. For the people in the placebo group, those who did not get any healing treatment, the number was higher. Ninety-three percent of the people who were in the placebo group were re-infected.

While 66 percent is not the best number the researchers would have hoped for, Hoffman calls the results a good first step.

"This is the highest level of efficacy against malaria infection ever seen in a vaccine trial in Africa."

The results of that trial were reported at the same time in the journal The Lancet Infectious Diseases.

Hoffman thinks Sanaria vaccines show more promise than others because they use the whole sporozoite to help the immune system.

He says other vaccine makers⁸ only use a small part of P. falciparum to try to get a good immune response against the malaria parasite⁴. He believes this is not as effective as his idea of using the whole sporozoite.

Sanaria plans more clinical trials of both vaccines throughout Africa, including in Mali, Burkina Faso, Kenya, Equitorial Guinea and Tanzania.

"For us, our raison d'etre [reason to be] for Sanaria is to develop a vaccine that can be used in what we call mass vaccination⁹ campaigns to immunize the entire population in a geographically¹⁰ defined area so that one can halt transmission and eliminate the parasite."

The vaccine news comes after a recent study says there are now malaria “superbugs” emerging in Southeast Asia. Researchers reporting in the journal The Lancet Infectious Diseases found that a kind of the P. falciparum parasite—the one being used for the vaccines by Sanaria-- is now becoming resistant¹¹ to the most effective malaria drug. They say the resistance is spreading.

Many people would benefit if they are successful, but those who would benefit the most are children in Africa.

The U.S. Centers for Disease Control and Prevention says most of the people who die from malaria are children in the African Region. It says most of the cases in the United States are in travelers and immigrants coming to the U.S. from countries where malaria is present—including many from sub-Saharan Africa and South Asia.

Words in This Story

effective – adj. producing a result that is wanted

immune system – n. the system that protects your body from diseases and infections

dose – n. the amount of a medicine, drug, or vitamin that is taken at one time

expose – v. to leave something uncovered without protection

raison d'etre – phrase. French for “reason to be”

1 vaccine   

n.牛痘苗，疫苗；adj.牛痘的，疫苗的

参考例句：

• The polio vaccine has saved millions of lives.脊髓灰质炎疫苗挽救了数以百万计的生命。
• She takes a vaccine against influenza every fall.她每年秋季接种流感疫苗。

2 vaccines   

疫苗，痘苗( vaccine的名词复数 )

参考例句：

• His team are at the forefront of scientific research into vaccines. 他的小组处于疫苗科研的最前沿。
• The vaccines were kept cool in refrigerators. 疫苗放在冰箱中冷藏。

3 malaria   

n.疟疾

参考例句：

• He had frequent attacks of malaria.他常患疟疾。
• Malaria is a kind of serious malady.疟疾是一种严重的疾病。

4 parasite   

n.寄生虫；寄生菌；食客

参考例句：

• The lazy man was a parasite on his family.那懒汉是家里的寄生虫。
• I don't want to be a parasite.I must earn my own way in life.我不想做寄生虫，我要自己养活自己。

5 parasites   

寄生物( parasite的名词复数 )； 靠他人为生的人； 诸虫

参考例句：

• These symptoms may be referable to virus infection rather than parasites. 这些症状也许是由病毒感染引起的，而与寄生虫无关。
• Kangaroos harbor a vast range of parasites. 袋鼠身上有各种各样的寄生虫。

6 placebo   

n.安慰剂；宽慰话

参考例句：

• The placebo has been found to work with a lot of different cases.人们已发现安慰剂能在很多不同的病例中发挥作用。
• The placebo effect refers to all the observable behaviors caused by placebo.安慰剂效应是指由安慰剂所引起的可观察的行为。

7 vaccinated   

[医]已接种的，种痘的，接种过疫菌的

参考例句：

• I was vaccinated against tetanus. 我接种了破伤风疫苗。
• Were you vaccinated against smallpox as a child? 你小时候打过天花疫苗吗？

8 makers   

n.制造者，制造商（maker的复数形式）

参考例句：

• The makers of the product assured us that there had been no sacrifice of quality. 这一产品的制造商向我们保证说他们没有牺牲质量。
• The makers are about to launch out a new product. 制造商们马上要生产一种新产品。 来自《简明英汉词典》

9 vaccination   

n.接种疫苗，种痘

参考例句：

• Vaccination is a preventive against smallpox.种痘是预防天花的方法。
• Doctors suggest getting a tetanus vaccination every ten years.医生建议每十年注射一次破伤风疫苗。

10 geographically   

adv.地理学上，在地理上，地理方面

参考例句：

• Geographically, the UK is on the periphery of Europe. 从地理位置上讲，英国处于欧洲边缘。 来自辞典例句
• All these events, however geographically remote, urgently affected Western financial centers. 所有这些事件，无论发生在地理上如何遥远的地方，都对西方金融中心产生紧迫的影响。 来自名作英译部分

11 resistant   

adj.(to)抵抗的，有抵抗力的

参考例句：

• Many pests are resistant to the insecticide.许多害虫对这种杀虫剂有抵抗力。
• They imposed their government by force on the resistant population.他们以武力把自己的统治强加在持反抗态度的人民头上。