A team of researchers at Icahn School of Medicine, Mount Sinai conducted a study using a new approach for flu vaccination that has brought us one step closer to a universal flu vaccine.
Flu causes significant illness and death worldwide. Flu is caused by the Influenza virus – a type of virus that undergoes antigenic drift, a mechanism by which the virus strain changes over time. As such, seasonal influenza vaccines are based on strain predictions for each season. Mismatches therefore occur, leading to the reduced effectiveness of these vaccines. Current vaccines are also ineffective during pandemics, as it usually takes months to develop a vaccine that matches the newly emerging strain. Hence, there is an immediate need for a universal flu vaccine that protects against all strains of the influenza virus.
Hemagglutinin is a protein on the surface of the influenza virus that binds the virus to the cell that is being infected. This protein consists of a head and a stalk – the head differs from strain to strain, while the stalk varies less among different strains. Researchers aimed to test vaccines that were developed against the stalk of this protein. The particular vaccines tested were called chimeric hemagglutinin-based vaccines (cHA-based vaccine).
The researchers enrolled 65 participants over one month (Oct 2017-Nov 2017) at two hospitals in the U.S. The study involved testing of several cHA- based vaccination regimens to see if they produced immunity against diverse influenza viruses. The results of the study were published in The Lancet Infectious Diseases.
The tested regimens included both live attenuated and inactivated vaccines. An adjuvant – a substance that boosts vaccine effectiveness – was also used as a part of the study. One dose of vaccine was followed by an additional boost dose in some regimens. The immunity that participants developed was measured through various parameters in blood samples, obtained at specific intervals following vaccination.
It was found that a significant immune response was attained after a single dose of inactivated cHA-based vaccine. All vaccine regimens tested induced good immunity after receiving a booster dose. The immunity induced provided broad protection against different types of influenza viruses including bat and bird influenza. All regimens were tolerable and had no safety concerns, as noted by the researchers.
“It was surprising to find that the inactivated formulation with adjuvant induced a very strong anti-stalk response already after the prime suggesting that one vaccination might be enough to induce protection against pandemic influenza viruses yet to arise. The results indicate that we are moving towards a universal influenza virus vaccine, but these are still interim results. Additional results will be available upon completion of the study at the end of 2019.” said Florian Krammer Ph.D., Professor of Microbiology Icahn School of Medicine.
Written by Sameena Ahmed
References:
THE LANCET infectious diseases: Immunogenicity of chimeric hemagglutinin-based, universal influenza virus vaccine candidates: interim results of a randomised, placebo-controlled, phase 1 trial.
EurekAlert! (17 Oct 2019) Mount Sinai researchers bring us one step closer to universal influenza vaccine. https://www.eurekalert.org/pub_releases/2019-10/tmsh-msr101619.php
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