Tuberculosis BCG vaccine gets into global Covid-19 trial

A trial into the effectiveness of an existing tuberculosis (TB) vaccine in protecting humans against the novel coronavirus has begun in Africa.

South Africa on Monday vaccinated health workers in a clinical trial in response to the Covid-19 pandemic.

A clinical research organisation in Cape Town, known as TASK, conducted the trial at Tygerberg Hospital, an officially-designated Covid-19 treatment centre.

Scientists used the Bacille Calmette-Guerin (BCG) vaccine to determine if a booster shot reduces the probability of infection and the severity of the symptoms.

The news comes as Kenyan researchers join their international counterparts in the search for a cure of the virus that causes respiratory illness, with plans for clinical trials for three drugs.

DISEASE SEVERITY

Since South Africa vaccinates all newborns with BCG, this study aims to determine if BCG re-vaccination reduces the probability of infection with the SARS-CoV-2 virus (the virus causing Covid-19) and/or the severity of symptoms of the disease, in a bid to help reduce the consequences of the pandemic, TASK said in a statement.

"The primary objective of this trial is to find out if BCG re-vaccination reduces disease severity, hospital admissions and death in frontline workers with direct patient contact."

The BCG vaccine, developed at France's Pasteur Institute 100 years ago, is one of the world's oldest and most-trusted immunisations.

It is primarily given to babies to protect them against tuberculosis for almost a century, but has been shown to shield them from other infections too, prompting scientists to investigate whether it can protect against the coronavirus.

DESPERATE SEARCH

In the trial, BCG booster shots were administered to 250 healthcare workers, while another 250 received a dummy formula, or placebo.

The trial mainly focused on health workers because they are most exposed to the virus, TASK said, adding that the results will be made public if they are positive enough.

In what is turning out to be a desperate search for treatment and a cure to fend off the Covid-19 pandemic, a decades-old tuberculosis vaccine, named after two French microbiologists could protect against the newest infectious disease.

Last Wednesday, American biopharmaceutical company Gilead Sciences announced that its drug, Remdesivir, sped the time it took patients to recover from Covid-19.

Full data from the study were released by the National Institute of Allergy and Infectious Diseases in a statement. Remdesivir is a broad-spectrum antiviral medication.

Researchers in Australia, Spain and the Netherlands are testing the idea that the vaccine could have broad power to boost the immune system against the novel coronavirus.

The Australian organisation behind the study, Murdoch Children's Research Institute (MCRI) in Melbourne, said on Tuesday that the BRACE trial would be expanding from 2,500 people in Australia alone, to over 10,000 frontline workers in Europe as well.

SCOPE

The BRACE trial, led by Nigel Curtis, was one of two clinical trials identified globally by the World Health Organization (WHO). Evidence will be evaluated once available.

Thanks in part to a $6.5million (about Sh692 million) grant from the Bill and Melinda Gates foundation, the team from MCRI will test BCG's effects at the current heart of the pandemic.

"We're expanding the study to Europe because there are more cases at the moment that will enable us to get a faster result," Curtis said.

"We'll be recruiting healthcare workers likely to come into contact with patients with Covid-19, so that's not just hospital doctors and nurses but also paramedics and ambulance drivers."

In the United States, a research group in Boston hopes to test the vaccine in frontline health workers for the same purpose.

MULTIPLE STUDIES

The interest stems from multiple studies over a number of years that point to the vaccine as having what are known as “off-target” benefits.

This BCG vaccine, named after two French microbiologists, consists of a live weakened strain of Mycobacterium bovis, a cousin of M. tuberculosis, the bacterium that causes tuberculosis and is estimated to have been given to more than four billion people, making it the most widely administered vaccine globally.

Because BCG protects babies against some viral infections in addition to TB, researchers decided to compare data from countries with and without mandatory BCG vaccination to see if immunisation policies are linked to the number or severity of Covid-19 infections.

A handful of preprint publications in the last two months noted that countries with an ongoing BCG vaccination program are experiencing lower death rates from Covid-19 than those without.

One study, for instance, found that mandatory BCG was associated with a significantly slower climb in both confirmed cases and deaths during the first 30-day period of an outbreak.

Another modelled mortality in two dozen countries and reported that those without universal BCG vaccination, such as Italy, the US and the Netherlands, were more severely affected by the pandemic than those with universal vaccination.

NO EVIDENCE

While global interest in the effects of BCG and it's potential for use against Covid-19 has recently piqued, health authorities including the WHO have been quick to point out that due to a lack of clinical trials, there was no evidence that it offers any protection against the virus.

"There is experimental evidence from both animal and human studies that the BCG vaccine has non-specific effects on the immune system. These effects have not been well characterised and their clinical relevance is unknown," the WHO said in a statement last month.

At the time the WHO said that BCG should not be used against Covid-19, at the risk of depleting supplies of the drug used for neonatal vaccination in countries with high instances of TB.

"BCG vaccination prevents severe forms of tuberculosis in children and diversion of local supplies may result in neonates not being vaccinated, resulting in an increase of disease and deaths from tuberculosis," the WHO said.

The Coronavirus Tracker