A “dream” vaccine to combat Covid-19 and new variants, as well as protecting against future pandemic pathogens, could soon be within reach, according to a new study.
Scientists from Singapore’s Duke-NUS Medical School and National Centre for Infectious Diseases (NCID) have discovered that survivors of the 2003 Severe Acute Respiratory Syndrome (Sars) outbreak who have been vaccinated with the Pfizer-BioNTech mRNA vaccine produce antibodies that can tackle a range of coronaviruses.
These highly potent functional antibodies are capable of neutralising not only all known variants of concerns (VOCs) linked to the current Sars-CoV-2 virus, but also other animal coronaviruses with the potential jump to humans.
The finding, published in the New England Journal of Medicine on Wednesday, is the first time that such cross-neutralising reactivity for coronaviruses has been demonstrated in humans, and experts believe it could be a game changer in the race to develop a universal coronavirus vaccine.
“Our study points to a novel strategy for the development of next-generation vaccines, which will not only help us control the current Covid-19 pandemic, but may also prevent or reduce the risk of future pandemics caused by related viruses,” said Professor Wang Linfa, who was involved in the research.
Prof Wang, a renowned biologist who heads Duke’s Emerging Infectious Diseases Programme, and who was one of eight scientists to discover that Sars originated in bats, said there were already “several companies at the contract stage” of developing the vaccine.
For their “simple but impactful” study, the scientists focused on a subgroup of the coronavirus family which relies on the ACE2 molecule - which the virus uses to latch onto human cells.
Collectively this group of viruses is called “sarbecovirus” and it includes Sars-CoV-1, the virus behind the original Sars, and Sars-CoV-2, the virus that triggers Covid-19 disease. A number of coronaviruses circulating in animals such as bats, pangolins and civets, also belong to this group.
While the exact route of transmission remains unknown, these viruses have the potential to jump from animals to humans and could start the next pandemic, experts have warned.
“We explored the possibility of inducing pan-sarbecovirus neutralising antibodies that can block the common human ACE2-virus interaction, which will be protective not only against all known and unknown Sars-CoV-2 VOCs, but also future sarbecoviruses,” said Dr Chee Wah Tan, co-author of the study.
To test their hypothesis, researchers recruited eight people who recovered from Sars 17 years ago, as well as ten healthy people and ten Covid-19 survivors. They compared the immune response of the three groups before and after they were vaccinated with the current Sars-CoV-2 vaccine.
In particular, they aimed to understand whether the antibodies triggered in the Sars survivors could wipe out both Sars-CoV-1 and Sars-CoV-2 viruses as well as other sarbecoviruses, including potentially zoonotic ones.
Before vaccination, Sars survivors had detectable neutralising antibodies against Sars CoV-1, but no or low-level anti-Sars-CoV-2 neutralising antibodies.
After receiving two doses of Pfizer's mRNA vaccine, all displayed high levels of neutralising antibodies that could tackle both Sars-Cov-2 and Sars-Cov-1. Most importantly, only the Sars survivors had a broad spectrum of neutralising antibodies against ten sarbecoviruses that were chosen to be examined.
The team is currently conducting a proof-of-concept study to develop a third-generation vaccine against different coronaviruses, called 3GCoVax.
The 3GCoVax could not only be used as a booster shot but to help the world fight the emergence of a “Sars3 or Sars4” pandemic, said Professor Wang.
The study provided a strategy to tackle the immune evasion shown by emerging variants of concern against the first-generation vaccines, in order to exit the pandemic, added Prof David Lye, head of the NCID’s infectious disease research and co-author of the study.
“We do hope to see this as a solution,” he said. “We need more people to come forward for the samples and development work but it’s a very exciting discovery.”
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