Strep A (Streptococcus pyogenes, group A streptococcus) is a leading cause of infection-related death across the world, killing more than 500,000 people each year. While in many cases, Strep A is responsible for relatively benign conditions such as tonsillitis and impetigo (school sores), untreated or repeated infections can lead to life-threatening diseases and auto-immune complications such as rheumatic fever, rheumatic heart disease and glomerulonephritis (inflammation of the kidneys). In some cases, invasive streptococcal disease can follow seemingly mild Strep A infections and quickly lead to necrotising fasciitis (‘flesh eating disease’) and toxic shock syndrome, an acute condition such as meningococcus, which can cause death within a matter of days.
“In some cases, invasive streptococcal disease can follow seemingly mild Strep A infections and quickly lead to necrotising fasciitis (‘flesh eating disease’) and toxic shock syndrome, an acute condition such as meningococcus, which can cause death within a matter of days.”
Who is most at risk of complications from Strep A?
While Strep A can affect people of all ages and socio-economic levels, its impacts are particularly devastating in developing countries and Indigenous populations within developed nations. Other at-risk groups include people who are homeless or with other measures of disadvantage, and the very young or elderly.
In Canada, invasive Strep A is a significant cause of premature mortality among First Nations peoples, while in Australia, Aboriginal and Torres Strait Islander peoples have some of the highest rates of Strep A infection and suffer the highest rate of rheumatic heart disease in the world. Social factors, such as crowded living environments that can increase the risk of Strep A infections spreading, and barriers to accessing health care, are the key contributors to the high rates of rheumatic heart disease in First Peoples communities.
When will we have a Strep A vaccine?
Natural immunity to Strep A takes years to develop. Professor Michael Good AO, from Griffith University’s Institute for Glycomics, says Strep A vaccine research had been hampered by the enormous diversity of the pathogen. “This is because there are multiple strains and it is a highly virulent organism that subverts immunity,” he said.
But, there is hope that a vaccine, developed by Professor Good’s team, could be available within years. The ground-breaking vaccine, currently at human trial stage in Canada, was created after the researchers identified two small molecules, known as epitopes, that are present on every Strep A strain. By combining these molecules, they were able to create a vaccine candidate capable of enhancing the body’s natural immune response, making it strong enough to fight off even the most virulent strains of the bacteria.
‘This [discovery] gives us a novel strategy to finally make a successful vaccine to protect against multiple Strep A strains,’ said Professor Good.
Volunteers in the clinical trial have received one dose of the vaccine. Now, thanks to a $5 million philanthropic donation from the US-based Leducq Foundation to Griffith University’s Institute for Glycomics, they will test different amounts of the vaccine to identify the optimal dose, and, in collaboration with the Murdoch Children’s Research institute, will test whether the vaccine can prevent a deliberate infection in adult volunteers.
These trials will pave the way for a comprehensive study of the vaccine in a Phase II clinical trial, where hundreds of volunteers will be vaccinated to test the vaccine’s ability to prevent community-acquired infections.
