One of the vaccine’s main selling points is its apparent ability to develop a more general immune response against SARS-CoV-2, the virus that causes COVID-19, rather than relying on the spike protein to do so. .
This means that the vaccine is more likely to be effective against the type of virus variants that we have already seen emerge and may emerge in the future. Some reports describe it as “variant evidence”.
The hope is that vaccines using this technology would be able to provide protection for longer, rather than continuing to be reformulated to get ahead of these newer variants.
How it works?
Valneva’s vaccine, called VLA2001, is based on proven vaccine technology. This is the technology used in the poliovirus vaccine and in some types of influenza vaccines. And the company already has a commercially available Japanese encephalitis vaccine based on the same technology.
VLA2001 uses an inactivated version of the whole virus, which cannot replicate itself or cause disease.
The virus is inactivated using a chemical called beta-propiolactone or BPL. This is widely used to inactivate other viruses for vaccines. It has even been used to make experimental versions of vaccines against SARS-CoV, the virus that causes SARS (severe acute respiratory syndrome).
This type of inactivation is expected to preserve the structure of viral proteins, as they would occur in nature. This means that the immune system will be presented with something similar to what happens naturally and develop a strong immune response.
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After being inactivated, the vaccine would be highly purified. Then an adjuvant (an immune stimulant) is added to induce a strong immune response.
VLA2001 is not the first inactivated vaccine against COVID-19. Major COVID-19 inactivated vaccines, such as those developed by Sinopharm and Bharat Biotech, have been approved for use in China and have received emergency approval in other countries, including India.
However, VLA2001 is the only COVID-19 vaccine candidate to use inactivated whole virus in clinical trials in the UK and mainland Europe.
What are the advantages that we know so far?
This approach to vaccine development introduces the immune system to all of the structural components of the SARS-CoV-2 virus, not just the spike protein, as many other COVID-19 vaccines do.
It is therefore believed that the vaccine from Valneva produces a more broadly protective immune response. In other words, antibodies and cells of the immune system are able to recognize and neutralize more fragments of the virus than the spike protein.
As a result, Valneva’s vaccine may be more effective in combating emerging variants of the COVID-19 virus and, if approved, play a useful role as a booster vaccine.
Valneva vaccine can be stored under standard cold chain conditions (2-8 ℃) and should be given as two injections.
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What about the results of clinical trials?
According to the company, no safety issues or serious adverse events have been associated with VLA2001 in early stage clinical trials.
VLA2001 was administered at a low, medium or high dose in these trials with all participants in the high dose group generating antibodies against the peak protein of the virus.
Measurement of the immune response in the high dose group after completing both doses indicated that antibody levels were, after two weeks, at least as high as those seen in patients naturally infected with SARS-CoV- 2.
Interestingly, VLA2001 elicited immune responses against a number of viral proteins (including the spike protein) in all participants, an encouraging sign that the vaccine may provide broad protection against COVID-19.
The vaccine has since moved on to Phase 3 clinical trials in the UK. The trial, which began in April 2021, will compare its safety and efficacy with the AstraZeneca vaccine.
The phase 3 trial is expected to be completed by the northern hemisphere fall this year. And if successful, would be subject to regulatory approval after that.
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Who is interested?
Despite the start of phase 3 clinical trials, the UK government has pre-ordered more than 100 million doses of the vaccine from Valneva, with the option of purchasing more. If the trials are successful and pass regulatory approval, that means the vaccine could be used as a booster in time for this year’s northern hemisphere winter.
Australia has confirmed that it is also in talks with Valeneva on importing the vaccine. Some countries in Europe would also be keen to conclude an agreement.
As new cases of COVID-19 increase around the world, we will continue to see new viral variants emerge that threaten to elude the protection offered by existing vaccines.
Already, we’re seeing vaccines from companies like Moderna and Novavax starting to reformulate their advanced protein-based vaccines to get ahead of emerging variants.
Thus, Valneva’s vaccine, with the potential to elicit a more broadly protective immune response, may prove to be a useful tool in combating the rise of the virus and its mutations. However, it remains to be seen whether the vaccine is truly “variant proof” or simply less affected by emerging variants.