malaria vaccine loses effectiveness
Last Updated : GMT 06:49:16
Arab Today, arab today
Arab Today, arab today
Last Updated : GMT 06:49:16
Arab Today, arab today

Over several years

Malaria vaccine loses effectiveness

Arab Today, arab today

Arab Today, arab today Malaria vaccine loses effectiveness

A health official tests for malaria, a disease that killed
Washington - Arab Today

An experimental vaccine against malaria known as Mosquirix -- or RTS,S -- weakens over time and is only about four percent effective over a seven-year span, researchers said Wednesday.

The findings, published in the New England Journal of Medicine, are based on a phase II clinical trial involving more than 400 young children in Kenya.

There is currently no vaccine against malaria on the world market and Mosquirix -- developed by the British pharmaceutical giant GlaxoSmithKline -- is the experimental vaccine in the most advanced stage of development. 

It has also been tested in a vast clinical trial that spanned seven African nations, and last year the European Medicines Agency gave it a "positive scientific opinion" regarding its use outside the European Union.

But the current study, involving 447 children from five to 17 months of age, suggested otherwise.

Some of the infants were given three doses of the malaria vaccine, while others received a vaccine against rabies for comparison.

In the first year, the protection against malaria among Mosquirix-vaccinated children was 35.9 percent. 
But after four years this protection fell to 2.5 percent.

Researchers said that on average, over the course of seven years, the vaccine would be considered just 4.4 percent effective against malaria.

This rate "was substantially lower than that seen over short-term follow up," said the study.

Furthermore, among children who were more frequently exposed to mosquito-borne malaria, cases of infection with the parasite P. falciparum in the fifth year were higher than in the control group.

Researchers said this phenomenon may be occurring because the vaccine protects against the earliest form of malaria’s life cycle, known as sporozoites, and reduces exposure to a later form, known as the blood-stage parasite, which causes the clinical symptoms of malaria such as fever, nausea, vomiting and diarrhea.

"The reduced exposure to blood-stage parasites among persons who have received the RTS,S/AS01 vaccine may lead to a slower acquisition of immunity to blood-stage parasites, leading to an increase in episodes of clinical malaria in later life," said the study.

The results of a larger, phase III clinical trial with the same vaccine, published last year, showed that three doses could reduce the risk of malaria by 28 percent over a period of four years.

The rate of protection rose to 36 percent when children received a fourth dose of the vaccine, suggesting that this additional dose was significant.

Malaria killed more than 400,000 people worldwide in 2015, with most of the deaths occurring in sub-Saharan Africa and most among children under age five.

The research was funded by the PATH Malaria Vaccine Initiative and the Bill and Melinda Gates Foundation. 

Source: AFP

arabstoday
arabstoday

Name *

E-mail *

Comment Title*

Comment *

: Characters Left

Mandatory *

Terms of use

Publishing Terms: Not to offend the author, or to persons or sanctities or attacking religions or divine self. And stay away from sectarian and racial incitement and insults.

I agree with the Terms of Use

Security Code*

malaria vaccine loses effectiveness malaria vaccine loses effectiveness

 



Name *

E-mail *

Comment Title*

Comment *

: Characters Left

Mandatory *

Terms of use

Publishing Terms: Not to offend the author, or to persons or sanctities or attacking religions or divine self. And stay away from sectarian and racial incitement and insults.

I agree with the Terms of Use

Security Code*

malaria vaccine loses effectiveness malaria vaccine loses effectiveness

 



GMT 13:42 2015 Saturday ,04 April

Libyan warplane targets camp in Gharyan town

GMT 15:14 2017 Wednesday ,01 March

UN documents nearly 1,500 child soldiers in Yemen

GMT 07:24 2017 Sunday ,01 October

Mexico unlikely to find more quake survivors

GMT 16:15 2015 Wednesday ,11 November

German intelligence 'spied' on Fabius, FBI, UN bodies

GMT 01:32 2017 Saturday ,15 April

Russia's Putin earns about 157,000 USD in 2016

GMT 16:30 2017 Saturday ,15 July

Minister of planning gives priority

GMT 19:45 2017 Wednesday ,05 April

President of Senegal Meets Attorney General

GMT 05:18 2017 Thursday ,21 September

Over 80 missing after migrant boat sinks off Libya

GMT 19:22 2017 Saturday ,01 April

UN: Number of Syrian Refugees Tops 5 million

GMT 15:16 2016 Thursday ,29 September

FBI to put up database on police use of deadly force

GMT 05:06 2016 Friday ,30 September

Indian markets open flat
Arab Today, arab today
 
 Arab Today Facebook,arab today facebook  Arab Today Twitter,arab today twitter Arab Today Rss,arab today rss  Arab Today Youtube,arab today youtube  Arab Today Youtube,arab today youtube

Maintained and developed by Arabs Today Group SAL.
All rights reserved to Arab Today Media Group 2021 ©

Maintained and developed by Arabs Today Group SAL.
All rights reserved to Arab Today Media Group 2021 ©

arabstoday arabstoday arabstoday arabstoday
arabstoday arabstoday arabstoday
arabstoday
بناية النخيل - رأس النبع _ خلف السفارة الفرنسية _بيروت - لبنان
arabstoday, Arabstoday, Arabstoday