What is Valneva for Covid vaccine?
The VLA2001 vaccine from the French manufacturer Valneva is an inactivated vaccine against the coronavirus. It is designed to train the human immune system to defend against the Sars-CoV-2 coronavirus.
VLA2001 consists of (whole) non-replicable Sars-CoV-2 virus particles. These inactivated viruses cannot cause Covid-19 disease.
The European Medicines Agency (EMA) issued a recommendation for the Covid-19 vaccine on June 23, 2022. This makes it the sixth available representative in the European Union. Valneva can be used for first-time vaccinations of individuals aged 18 to 50 years. This means that second or third vaccinations are not (yet) recommended at this time.
Inactivated vaccines have been around for a long time. For example, commonly used vaccines – such as those against polio or TBE – are based on the same mode of action as Valneva.
Inactivated inactivated vaccines have one advantage: the immune system learns all the recognition structures (antigens) of the coronavirus. This means that, unlike with the previously approved Covid-19 vaccines, the human immune system not only forms antibodies against the spike protein, but also against other structures of the outer envelope of Sars-CoV-2.
What is known about the Valneva vaccine?
Put simply, this is not a “classic (placebo-controlled) efficacy study”, but rather a direct comparison with an already tested and approved coronavirus vaccine.
In this case, the manufacturer Valneva sought a comparison with Vaxzevria from AstraZeneca. The preceding intensive safety review before – and the safety data collected after – the approval of Vaxzevria, provide a solid data basis for such an approach.
Another aspect from a purely practical point of view: in the meantime, the Corona pandemic has now been going on for some time. It is therefore increasingly difficult to find suitable study participants for large efficacy studies who have neither already been vaccinated nor infected with the corona virus.
The study examined the amount of (neutralizing) antibodies produced and tested overall tolerability.
Typical vaccine reactions were mild and transient. Safety is now closely and continuously monitored by the PEI after approval. The antibody response was comparable to that of Vaxzevria. The vaccine elicited similarly strong immune responses in all age groups studied. However, middle age groups from 50 years upwards were not included, so that no further conclusions can be drawn from the data sets.
Which active enhancers (adjuvants) does Valneva contain?
Unlike mRNA and vector vaccines, inactivated vaccines rely on certain (adjuvant) substances to elicit a strong immune response. Without these boosters – also called adjuvants – inactivated vaccines are usually not sufficiently effective.
Adjuvants act like a “warning signal” on the vaccinee’s immune system. They attract specialized immune cells to the area of the injection site. Only then is the desired immune response to the inactivated virus particles initiated in sufficient strength.
The following adjuvants are part of the VLA2001 Valneva vaccine:
Alum: Usually a mixture of different aluminum salts. Vaccine manufacturers have used alum for a long time – for example, in diphtheria and tetanus vaccines, as well as many others. Although the adjuvant has been used for a long time, its actual mechanism of action is not yet fully understood. Experts assume that Alum acts indirectly. It causes a non-specific local inflammation in the area of the injection site.
The use of Alum is associated with a certain risk of complications (in very rare cases) (e.g.: Autoimmune Syndrome Induced by Adjuvants, ASIA for short). Nevertheless, experts assume a clearly positive risk-benefit ratio.
This CpG motif is found in particular in the genetic material of a wide variety of bacteria and viruses – hence the term “conserved structures”. Immune cells are able to recognize these characteristic CpG motifs via specialized receptors (Toll-like receptor, TLR9).
This enhances the immune response to the vaccine or to the inactivated virus particles. The CpG adjuvant has already proven effective and tolerable in hepatitis B vaccination (HBV vaccination).
How is the Valneva vaccine produced?
First, the vaccine manufacturer amplifies the natural Sars-CoV-2 pathogen in the laboratory. To do this, so-called CCL81 Vero cells are grown in a cell culture in the laboratory. Vero cells themselves are stem cell-like cells derived from the kidney cells of primates.
These cells are now infected with Sars-CoV-2. The pathogen then multiplies rapidly inside the cell. At a certain point, a sufficient number of new virus particles are present in the cell cultures. In a subsequent step, the Vero cells are destroyed (cell lysis) and the virus particles are “collected”.
For this purpose, the virus particles are separated from the remaining Vero cell fragments by certain purification procedures.
