There is no vaccine against the novel coronavirus, called SARS-CoV-2, which is spreading rapidly around the world. However, scientists in several countries tested a century-old tuberculosis (TB) vaccine to see if it might boost the immune system to reduce respiratory symptoms in people who get new coronavirus infections.
Researchers in Australia and Europe are testing whether the Bacille Calmette-Guerin (BCG) vaccine, introduced in the 1920s to fight tuberculosis (TB) — a bacterial infection — might be deployed to combat Covid-19, the respiratory disease caused by the novel coronavirus.
Countries which have a widespread vaccination program involving the BCG jab have a coronavirus death rate almost six times lower than nations that do not use it, a study reveals.
BGC have other benefits
The BCG vaccine contains a live but weakened strain of the tuberculosis (TB) bacteria that provokes the body to develop antibodies to attack it. This is called an adaptive immune response, because the body develops a defence against a specific disease-causing microorganism, or pathogen, after encountering it.
Most vaccines create an adaptive immune response to a single pathogen, reports Reuters.
Previous trials discovered people that receive the jab, which costs as little as £30, have improved immune systems and are able to protect themselves from infection.
One study in Guinea-Bissau found 50% lower mortality rates in children vaccinated with BCG than in kids who did not get this vaccine. That is a much bigger drop in deaths than could be explained by a reduction in TB cases.
Some studies have found similar reductions in respiratory infections among teens and the elderly.
For example, in a trial among Native Americans, BCG vaccination in childhood was able to offer protection against TB up to 60 years after vaccination.
The precise way this durable vaccine helps fend off other infections is relatively unknown but it may be by boosting the immune system's innate mechanisms, first-line defences that keep a variety of pathogens from entering the body or from establishing an infection.
These so-called off-target effects include enhanced protection against respiratory diseases, and have been recognized by the World Health Organization (WHO).
In the UK, all schoolchildren between ten and 14 were injected with the vaccine between 1953 and 2005.
As TB infection rates dropped, doctors abandoned mass vaccination and, in 2005, switched to targeting only the most at risk — such as babies with infected relatives, reports Daily Mail
Researchers hope it will turbo-charge the immune system so that it is in a heightened state of readiness and able to detect and destroy the virus before it wreaks havoc on the body.
Factors to skew the findings
The researchers adjusted for factors which can skew the findings, such as a nation's wealth and the percentage of elderly people in its population.
They then looked at the mortality per one million residents of every country with sufficient data.
Researchers from the US write in their paper: “After adjusting for country economic status, proportion of older population and aligning the epidemic trajectories of the highest hit countries, the intriguing observation of a significant association between BCG use and lower Covid-19-attributable mortality remained discernable.”
The findings were published online on archive site medRxiv and not in a journal as the research has yet to be peer-reviewed — the process in which other academics scrutinize research.
The Johns Hopkins Bloomberg School of Public Health experts pooled publicly available data for the analysis.
An estimate on case fatality rate was produced from the best available data on mortality for the top 50 countries reporting highest case events.
“In order to mitigate the bias centered around the differential epidemic time curves experienced by the different countries, we calculated days from the 100th Covid-19 positive case to align the countries on a more comparable time curve,” the researchers explain.
The cases and deaths was then compared to vaccination programs for the BCG vaccine.
Average death rate was also found to vary significantly according to a country's economic classification.
Covid-19 mortality per one million for low-middle-income, upper-middle-income and high-income countries were 0.4, 0.65 and 5.5, respectively
Researchers call the fact that the wealthier nations have a higher death rate “counter-intuitive”.
The academics are unable to explain why that is but point to previous research which states
“deaths from acute respiratory illness are typically higher in low-income settings due to multiple socio-demographic and economic risk factors.”
For example, Covid-19 is known to be more dangerous to people over the age of 65, and this demographic is less populous in poorer nations.
The researchers say their results should be taken with caution as there are several issues that may distort the findings.
Trials underway
Despite all these caveats, the inverse relationship between country economic status and Covid-19 attributable mortality, and the strong ecological association with BCG vaccination are intriguing.
The findings warrant deeper epidemiological scrutiny and prospective evaluation in individually randomized trials.
Trials to assess the usefulness of the BCG vaccine in the fight against the coronavirus pandemic are already underway.
Last month, a trial started which includes 4,000 healthcare workers in Australia.
The trial will be led by Researchers at Melbourne's Murdoch Children's Research Institute and involve 4,000 health workers in various hospitals across the country.
Researchers hope administering the vaccine and boosting “innate immunity” can buy enough time for specialized treatments and vaccines to be developed.
However, a run on the BCG vaccine to fight Covid-19 might cause shortages for children as BCG is currently given to around 130 million children every year to protect them from TB.
The fast spreading coronavirus, which was first reported in China's Wuhan, has claimed above 88,600 lives and infected more than 1,521,900 people across the world till date, according to Worldometers.
As many as 332,291 people have recovered from Covid-19, a disease caused by a new strain of coronavirus, which has spread to 209 countries and territories across the world.
