The wound of the last Ebola crisis a few years ago is still deeply engraved into the minds of those who were affected by the deadly virus. The Ebola outbreak is not the first infectious disease crisis that has plagued humanity, and it is very unlikely that it will be the last.

The deployment of effective vaccination thus becomes essential in the decades-long fight against these lethal bugs. There are tremendous efforts and resources being invested into developing effective vaccines against hundreds of infectious diseases.

According to a 2016 report, there were close to 260 vaccines in active development phases for infectious diseases in last year alone. The industry has made two significant advances in vaccine development, one in combating malaria infection and another one specifically targeting the Ebola virus.

The number of newly diagnosed malaria cases per population in Malaysia has been steadily declining over the years. However, malaria remains a public health concern. The Ebola outbreak, on the other hand, had not affected the country in any substantial manner but left a permanent scar on the population psychologically.

Malaria vaccine


Earlier this year, a group of researchers from the Institute of Tropical Medicine, University of Tübingen reported a malaria immunisation method that was hailed as “100% effective”. The study reported a new immunisation technique that employed direct venous inoculation of Plasmodium falciparum sporozoites (PfSPZ) in healthy individuals without the disease.

These healthy volunteers were given oral doses of chloroquine for chemoprophylaxis as well. At 28-day intervals, the vaccine prevented nine out of nine volunteers from being infected by the parasites.

Professor Peter Kremsner who was part of the investigating team said the team utilised the whole malaria parasite to induce immunity instead of relying on parts of the malaria parasite surface molecules. This was the major difference with the previous vaccine, Mosquirix, ed.

He argued that the existing Mosquirix vaccine only demonstrated a 30% to 50% effectiveness as only parts of the parasite could be recognised. When the entire cell was used, it increased the number of potential molecules that could trigger the immune system that led to the remarkable results.

“The malaria parasite molecules then trigger an immune response which, as we have shown, is 100% protective,” claimed Kremsner in an interview.

The team is currently working to refine the vaccine dosage and time frame, and postulate that the vaccine will be ready for licensing in two years’ time.

Ebola vaccine


At around the same time as Kremsner’s malaria vaccine publication, another breakthrough vaccine study to fight Ebola infection was published. The vaccine, known as rVSV-ZEBOV, was developed through a network of international organisations such as the World Health Organisation and Doctors Without Borders, together with Guinea’s Ministry of Health and the Norwegian Institute of Public Health.

The trial was conducted in Guinea and recorded great success. The rVSV-ZEBOV trial involved over 11,000 people. Among the 5,837 subjects who received the vaccine, none of them showed signs of Ebola infection in 10 days or more after vaccination. Comparatively, in the group which did not receive vaccination, 23 cases of infection were recorded.

The vaccine trial was conducted via the "ring vaccination" approach where the researchers traced all persons who were suspected to have made contact with the Ebola patient, thus forming clusters, or "rings", of people. These rings were then randomised to receive the vaccine immediately or after a three-week delay.

An additional observation from such designs was the existence of "herd immunity" in those who were not vaccinated but included into the rings, thereby further strengthening the need for the society to undertake mass vaccination programme.

Read more:
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Algorithmic disease surveillance: Staying ahead of an epidemic
Joshua Tan: Malaysian scientist renowned for malaria research

Sources:
PhRMA. Medicines in Development for Vaccine: 2016 Updates. Washington D.C.; 2016.
https://www.health.ny.gov/diseases/chronic/basicstat.htm
http://www.dw.com/en/kremsner-new-malaria-vaccine-is-100-percent-protective/a-37587227
Sterile protection against human malaria by chemoattenuated PfSPZ vaccine. Nature. 2017 Feb 15;542(7642):445–9.
http://www.who.int/mediacentre/news/releases/2016/ebola-vaccine-results/en/
Efficacy and effectiveness of an rVSV-vectored vaccine expressing Ebola surface glycoprotein: interim results from the Guinea ring vaccination cluster-randomised trial. Lancet. 2015;386(9996):857–66.