One of the emerging questions about the coronavirus that scientists are working to understand is why developing countries are showing markedly lower rates of mortality in COVID-19 cases than expected.
In a new study, researchers found that Bacille Calmette-Guérin (BCG), a tuberculosis vaccine routinely given to children in countries with high rates of tuberculosis infection, might play a big role in reducing mortality rates in COVID-19.
The research was conducted by a team at the National Institutes of Health.
In their initial research, the team found that countries with high rates of BCG vaccinations had lower rates of mortality.
But all countries are different: Guatemala has a younger population than Italy, so they had to make adjustments to the data to accommodate those differences.
The team collected coronavirus mortality data from around the world.
From that data, the team adjusted for variables, such as income, access to education and health services, population size and densities, and age distribution.
Through all of the variables, a link held showing that countries with higher rates of BCG vaccinations had lower peak mortality rates from COVID-19.
One sample that stood out was Germany, which had different vaccine plans prior to the country’s unification in 1990.
While West Germany provided BCG vaccines to infants from 1961 to 1998, East Germany started their BCG vaccinations a decade earlier but stopped in 1975.
This means that older Germans—the population most at risk from COVID-19—in the country’s eastern states would have more protection from the current pandemic than their peers in western German states.
Recent data shows this to be the case: western German states have experienced mortality rates that are 2.9 times higher than those in eastern Germany.
The team says the purpose of using the BCG vaccine to protect from severe COVID-19 would be to stimulate a broad, innate, rapid-response immunity.
The BCG vaccines have already been shown to provide broad cross-protection for a number of viral respiratory illnesses in addition to tuberculosis.
The team stresses that the findings are preliminary and that further research is needed to support their results and determine what the next steps should be for researchers.
The World Health Organization noted that there is no current evidence that the BCG vaccine can protect people from COVID-19 infections, and stated that it does not currently recommend BCG vaccinations for the prevention of COVID-19.
There are currently clinical trials underway to establish whether BCG vaccination in adults confers protection from severe COVID-19.
While a direct correlation between BCG vaccinations and a reduction in coronavirus mortalities still needs to be understood more fully, researchers hold hope that the BCG vaccine might be able to provide at least short-term protections against severe COVID-19, particularly for front-line medical workers or high-risk patients.
And, if BCG does provide short-term protection, there are longer-term considerations about how countries could best utilize BCG vaccines to reduce mortality rates for future viral outbreaks that target the human respiratory system.
One author of the study is Assistant Professor Luis Escobar of the College of Natural Resources and Environment.
The study is published in PNAS.
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