Ebola vaccine tested in Kenya is safe: report

The results from the Ebola vaccine trials partly conducted in Kenya have been published this week in the New England Journal of Medicine.

The data suggests that the vaccine is safe and that those vaccinated have produced antibodies that are likely to be protective should an infection arise.

A total of 138 volunteers were recruited for this study: 59 from Switzerland, 39 from Gabon, 20 from Germany and 20 from Kenya.

All 20 volunteers from Kenya were doctors, nurses and scientists from the KEMRI-Wellcome Trust Research Project (KEMRI-WTRP) and the Kilifi County Hospital.

The participants will continue to be followed up for a year so as to see how long they will continue to produce antibodies likely to be protective against Ebola infection.

The vaccine was made by the Public Health Agency of Canada by combining the Vesicular Stomatitis Virus (VSV) with a portion of the protein covering the Ebola virus, hence the name of the vaccine Vesicular Stomatitis Virus Ebola Vaccine (VSV-EBOV).

The agency had already started human trials of this vaccine at the Walter Reed Institute of Research in the USA in October 2014 and have partnered with the World Health Organization (WHO) in order to hasten the process of vaccine development.

HAPPY TO HELP

Testing of this vaccine required co-operation between Kenya and West African scientists who received support from WHO and other European institutions. Dr Patricia Njuguna, the lead investigator of the Kenyan arm of the study was pleased with the way the trial ran and hoped to see more.

‘There is a need for African scientists to get involved in early phase studies especially when the disease primarily affects Africa,’ Dr Njuguna said.

The trial participants were selected among medical workers as it has been shown throughout the current outbreak that health workers are most likely to come into contact with Ebola patients and therefore most likely to spread the infection to the rest of the community. Protection of health workers would mean protection to the whole population.

Munga Mwachiro and Dr Sassy Molyneux were among those who participated in this vaccine trial.

Mwachiro, a nurse in the KEMRI-WTRP was eager to participate in the study, "I have always wanted to be part of a worthy cause in health care; it is the reason I became a nurse in the first place. It also presented an opportunity for me to learn more about a disease that has been ravaging the West of Africa, so despite my dislike of injections, I volunteered for this study," he said.

Dr Sassy Molyneux is a senior social research scientist at the KEMRI-WTRP.

"Much of my work over my time here has focused on how researchers interact with communities, and on the priorities, experiences and concerns of research participants. So when the chance finally came for me to be involved in a Phase 1 trial myself, I leapt at the opportunity", said Dr Molyneux.

Their reasons for participating deferred as did their response to the vaccine.

‘I did not have any reactions to the vaccine but my friends did. They would say ‘are you sure you won’t get Ebola and spread it to us all?’ I’d explain that when you get the Tetanus jab you don’t get Tetanus but they’d keep joking and checking me out for manifestations of the disease,’ Mr Mwachiro said.

INTERESTING SIDE EFFECTS

However, Dr Sassy Molyneux did react slightly to the vaccination.

"As it happens I think I’m the only person in Kilifi who has had an interesting side effect – a swollen knee 10 days post vaccine, lasting 10 days or so. But it took me two days to remember I was in the trial and realised it might be linked and reported this to the investigators," said Dr Molyneux.

Arthritis was one of the few side effects of the vaccine. However, this was a transient response to the vaccine.

About a quarter of the participants from all 4 study sites also had vaccine-induced fevers. All the side effects related to vaccination were carefully monitored.

None of them was deemed severe enough to counter balance the benefits that the vaccine itself would bring.

The results from this endeavour are so promising that VSV-EBOVis now being used in the affected areas to combat the current outbreak.

The Guinean Government with the World Health Organization (WHO) initiated the very first efficacy trial of an Ebola vaccine in the third week of March, in an affected community of the Basse-Guinée, one of the areas where most Ebola cases are found in the country.  

Although all 138 participants who received the vaccine produced antibodies against a part of the Ebola virus, it will not be known whether this antibody response is protective, unless it is used in the context of an outbreak.

Vaccinating everyone may lead to wrong conclusions of vaccine efficacy, hence the need for a group to compare the vaccines with.

For most vaccine trials, a group of people are given the study vaccine and the comparison group given an alternative vaccine or placebo unrelated to the disease under study.

This would be difficult to do for Ebola due to the likely expected positive effect of the vaccine and the deadly impact of the disease.

WHO have therefore opted to go for ‘ring vaccination’. The ring vaccination strategy consists in identifying recently infected patients and vaccinating all their contacts, thereby creating a ‘ring of immunity’ around them to stop the virus from spreading

Once a case is diagnosed, a ring of contacts will be vaccinated either immediately or three weeks after the diagnosis.

WORST OUTBREAK

So the groups to be compared will be those vaccinated immediately and those vaccinated later. The data will show whether vaccination actually works in field conditions.

In the next 6 to 8 weeks, it is expected that a total of 10,000 people in 190 rings will be vaccinated.

These people will be monitored closely for 3 months and the results of this study will be expected at the end of July.

Ebola is still ravaging West Africa. According to the World Health Organization ‘Ebola Situation Report’ of 25^th March 2015, so far, there have been 24,907 cases of Ebola with 10,326 deaths.

Sierra Leone, Liberia and Guinea in that order have borne the brunt of infections and deaths.

New cases are still being detected and the vaccine will strengthen the current efforts on the ground to control the worst Ebola outbreak ever experienced.