WHAT HAPPEN WITH THE MALARIA VACCINE

Tuesday, May 02, 2017

The world’s first vaccine against malaria will be introduced in three countries - Ghana, Kenya and Malawi - starting in 2018.

What is Malaria?

Malaria in humans is caused by one of four protozoan species. All species are transmitted by the bite of an infected female mosquito. Occasionally Malaria transmission occurs by blood transfusion or congenitally from mother to foetus.

Malaria Symptoms and Signs

Malaria is characterized by fever and flu-like symptoms, including chills, headache, body aches and fatigue; these symptoms may occur at intervals. Malaria may be associated with anaemia and jaundice, and may cause kidney failure, coma and death. Deaths due to Malaria are preventable.

Malaria Prevention

Because no currently available drug regimen guarantees 100% protection against Malaria, prevention of infection requires taking antimalarial medication as directed in addition to prevention of mosquito bites. Mosquitoes that carry Malaria have nocturnal feeding habits, thus Malaria transmission occurs primarily between dusk and dawn. Measures to reduce mosquito contact during critical hours include:

Remaining in well-screened or air conditioned areas

Using mosquito nets treated with Permethrin

Wearing clothing that covers most of the body and has been treated with Permethrin

Using insect repellents containing appropriate levels of DEET

Using insecticides in living and sleeping areas where appropriate

Passport Health carries CDC and WHO recommended insect repellents for purchase.

Immunization, Vaccines and Biologicals

Malaria vaccines

Introduction and malaria vaccine development

Status of vaccine development

The complexity of the malaria parasite makes development of a malaria vaccine a very difficult task. Recent progress has been made with the completion of a Phase 3 trial of the RTS, S/AS01 candidate vaccine and review by the European Medicines Agency and WHO.

There is currently no commercially available malaria vaccine. Over 20 other vaccine constructs are currently being evaluated in clinical trials or are in advanced preclinical development. See link to Rainbow table below.

 WHO rainbow table

The malaria vaccine candidate RTS, S/AS01

RTS,S/AS01 is the most advanced vaccine candidate against the most deadly form of human malaria, Plasmodium falciparum. A Phase 3 trial with 15 460 children in seven countries in sub-Saharan Africa (Burkina Faso, Gabon, Ghana, Kenya, Malawi, Mozambique, and the United Republic of Tanzania) began in May 2009 and has now been completed.

 There were two age categories in the trial:

Children aged 5-17 months at first dose receiving the RTS,S/AS01 vaccine or a comparator vaccine; and

Children aged 6-14 weeks at first dose who receive the RTS,S/AS01 vaccine or a comparator vaccine in co-administration with the pentavalent vaccine from the routine immunization schedule.

 All children received 3 doses of study vaccines vaccine at 1 month intervals. The role of a fourth dose 20 months after the first dose was also evaluated.

 After review of the study data, the European Medicines Agency issued a positive Scientific Opinion about the risk-benefit balance, upon agreement with the manufacturing company about further research plans as part of Phase 4 evaluation.

 WHO, upon review of the data, recommended pilot implementation studies to be conducted for further evaluation of implement ability of a four dose schedule in children aged 5-17 months at first dose and further evaluation of the risk/benefit profile.

 A comprehensive WHO Q&A gives further information on the RTS,S/AS01 malaria vaccine implementation programme (MVIP).

 The world’s first vaccine against malaria will be introduced in three countries - Ghana, Kenya and Malawi - starting in 2018.

The RTS,S vaccine trains the immune system to attack the malaria parasite, which is spread by mosquito bites.

The World Health Organization (WHO) said the jab had the potential to save tens of thousands of lives.

But it is not yet clear if it will be feasible to use in the poorest parts of the world.

The vaccine needs to be given four times - once a month for three months and then a fourth dose 18 months later.

This has been achieved in tightly controlled and well-funded clinical trials, but it is not yet clear if it can be done in the “real-world” where access to health care is limited.

It is why the WHO is running pilots in three countries to see if a full malaria vaccine programme could be started. It will also continue to assess the safety and effectiveness of the vaccination.

Dr Matshidiso Moeti, the WHO regional director for Africa, said: “The prospect of a malaria vaccine is great news.

“Information gathered in the pilot programme will help us make decisions on the wider use of this vaccine.

“Combined with existing malaria interventions, such a vaccine would have the potential to save tens of thousands of lives in Africa.”

The pilot will involve more than 750,000 children aged between five and 17 months. Around half will get the vaccine in order to compare the jab’s real-world effectiveness.

In this age group, the four doses have been shown to prevent nearly four in ten cases of malaria.

This is much lower than approved vaccines for other conditions.

Malaria vaccine: How good is good enough?

It also cuts the most severe cases by a third and reduces the number of children needing hospital treatment or blood transfusions.

But the benefits fall off significantly without the crucial fourth dose.

Ghana, Kenya and Malawi were chosen because they already run large programmes to tackle malaria, including the use of bed nets, yet still have high numbers of cases.

Each country will decide how to run the vaccination pilots, but high-risk areas are likely to be prioritised.

Despite huge progress, there are still 212 million new cases of malaria each year and 429,000 deaths.

Africa is the hardest hit and most of the deaths are in children.

The pilots are being funded by: Gavi, the Vaccine Alliance, the Global Fund to Fight Aids, Tuberculosis and Malaria, Unit aid, the WHO and GSK.

Dr Seth Berkley, the chief executive of Gavi, said: “The world’s first malaria vaccine is a real achievement that has been 30 years in the making.

“Today’s announcement marks an important step towards potentially making it available on a global scale.

“Malaria places a terrible burden on many of the world’s poorest countries, claiming thousands of lives and holding back economies.

“These pilots are crucial to determining the impact this vaccine could have on reducing this toll.”

The PfSPZ malaria vaccine was 100% effective in U.S. clinical trials and 48% effective in trials run in Mali, exhibiting a previously unseen level of sustained efficacy in that region.

 PfSPZ is just one of several promising malaria vaccines in development, any of which could help us eradicated this deadly disease that claimed almost half a million lives in 2015 alone.

MOSQUITOS: VECTORS OF INFECTION

Mosquitos are ugly creatures. They buzz, bite, and bother you, but more than just being annoying, they harbor parasites that transmit malaria. A person infected by one of these parasites via a mosquito bite can experience fever, chills, vomiting, and sometimes even death.

The World Health Organization predicts that almost 3.2 billion people — that’s half the world’s population — is at risk of catching this disease, and among those at risk, 214 million people were infected in 2015. Of those infected with malaria, at least 438,000 people passed away.

While global efforts have successfully reduced the incidences of malaria by 60 percent since 2000, researchers may have just found a way to take that progress even further thanks to a new malaria vaccine.

A NEW WAY TO VACCINATE

A malaria vaccine has been particularly elusive in the medical community because malaria originates from a parasite and not a virus. Therefore, a live but weakened form of the parasite that infects humans was used in the creation of this new investigational vaccine, Sanaria® PfSPZ. The weakened sporozoites parasite was developed by Sanaria Inc. through a clinical study conducted by researchers from the National Institute of Health’s (NIH) National Institute of Allergy and Infection Diseases (NIAID) division and the University of Bamako in Bamako, Mali.

For further information search for WHO, UNICEF web sites, MRC Gambia, send email to azadehhassanmd10@gmail.com, Text only to 002207774469/3774469.

Author DR AZADEH Senior Lecturer at the University of the Gambia, Senior Consultant in Obstetrics & Gynaecology, Clinical Director at the Medicare Health Services.