Scientists have uncovered a link between a COVID-19 vaccine complication and that caused by a rare ‘common cold’ blood disease.
The research, led by Flinders University and international experts, deepens our understanding of vaccine-induced immune thrombocytopenia and thrombosis (known as VITT).
Following the first waves of the COVID-19 pandemic in 2020, governments across the world implemented a range of infection control measures, including a mass vaccination programme.
Since then, more than 13.5 billion doses of Covid vaccines have been administered globally, saving over one million lives in Europe alone, a recent study by the World Health Organization found.
Although effective in reducing the severity of COVID-19 infection, in 2021 it emerged that a vanishingly small percentage of individuals receiving adenoviral vector-based vaccines, which use a harmless virus as a delivery system, experienced vaccine-induced immune thrombocytopenia and thrombosis (VITT).
VITT is charecterised by life-threatening thromboses, or clotting of the blood, in multiple body sites.
VITT was found to be caused by an unusually dangerous blood autoantibody directed against a protein termed platelet factor 4 (or PF4).
In separate research in 2023, researchers from Canada, North America, Germany and Italy described a virtually identical disorder with the same PF4 antibody that was fatal in some cases after natural adenovirus (common cold) infection
Flinders University researchers Doctor Jing Jing Wang and Flinders Professor Tom Gordon, Head of Immunology at SA Pathology in South Australia, led a previous study in 2022 which cracked the molecular code of the PF4 antibody and identified a genetic risk factor related to an antibody gene termed IGLV3.21*02.
Now, the Flinders group has collaborated with this international group of researchers to find that the PF4 antibodies in both adenovirus infection-associated VITT and classic adenoviral vectored VITT share identical molecular fingerprints or signatures.
The research will also have implications for improving vaccine development, says Flinders University researcher Doctor Wang, first author on the new article published in the New England Journal of Medicine.
“These findings, using a completely new approach for targeting blood antibodies developed at Flinders University, indicate a common triggering factor on virus and vaccine structures that initiates the pathological pF4 antibodies,” explained Professor Gordon.
The research will also have implications for improving vaccine development, researcher says
PA
“Indeed, the pathways of lethal antibody production in these disorders must be virtually identical and have similar genetic risk factors.
“Our findings have the important clinical implication that lessons learned from VITT are applicable to rare cases of blood clotting after adenovirus (a common cold) infections, as well as having implications for vaccine development,” he said.
Editor’s take
The finding is important in understanding the impact of the global vaccination campaign but it must be stressed just how vanishingly rare complications from the vaccine are.
Numerous studies suggest the benefits of getting vaccinated overwhelmingly outweigh the risks for the majority of people.
In the UK, the safety of the vaccines has been extensively reviewed in both adults and children by the independent Medicines and Healthcare products Regulatory Agency (MHRA).
And Covid is here to stay.
NHS England is urging at-risk groups to get vaccinated against COVID-19 this spring.
People at increased risk from severe illness can get the vaccine, including those aged 75 or over (on 30 June 2024), people with a weakened immune system or who live in an older adult care home.