It is easier to solve a problem early if we start looking for many different solutions at the same time. This is how clearly those who are trying to develop anti-SARS-CoV-2 vaccines (in the plural, yes) have seen it, at an unprecedented rate. Doing it from several approaches simultaneously will mitigate the possible failures linked to specific developments.
What seems indisputable is that, if in the end we have multiple vaccine candidates that show efficacy, it will be better for everyone. Especially since the effectiveness and durability in the total protection of the candidates will only be known with time.
However, it is equally true that the rapid and urgent march in manufacturing, spurred by health pressure and alleged political motivations, has increased the population’s distrust of SARS-CoV-2 vaccines.
For this reason, a few weeks ago the CEOs of Pfizer Inc., AstraZeneca, GlaxoSmithKline, Moderna Therapeutics, Novavax Inc., BioNTech, Sanofi, Johnson & Johnson and Merck (MSD outside the United States and Canada), nine of the main companies Pharmaceutical companies that are involved in the development of vaccines against COVID-19, signed an unprecedented commitment. In which they agreed to defend the integrity of the scientific process in the development of vaccines.
Pharmaceutical companies have committed to developing and testing potential vaccines for COVID-19 in accordance with high ethical standards and the strongest scientific principles. Among the orchestrated points, they established that the safety and well-being of vaccinated people should always be a top priority.
They also agreed on the importance of continuing to meet scientific and ethical standards with regard to conducting clinical trials. And do it without renouncing the rigor of the manufacturing processes. In addition to committing to only submit vaccines for approval or authorization for emergency use after demonstrating their safety and efficacy through Phase III clinical studies. Those studies will always be designed to meet the requirements of expert regulatory authorities such as the US Food and Drug Administration (FDA). Finally, they agreed to work to ensure a sufficient supply and a variety of vaccine options, including those suitable for global access.
The most promising candidates
The search for a vaccine for COVID-19 has involved thousands of researchers and volunteers from around the world. More than 150 different vaccines against SARS-CoV-2 are currently being developed. Several of them have already reached Phase III (trials involving thousands to tens of thousands of people) or have even surpassed it.
Candidates leading the race include the ChAdOx1 nCoV-19 vaccine, from the University of Oxford and the company AstraZeneca, based on a chimpanzee adenovirus vaccine vector. Chimp adenoviral vectors are a well-studied type of vaccine that has been used safely in thousands of subjects. The Oxford vaccine contains the genetic sequence of a specific protein ( Spike protein ) on the surface of the virus. When the vaccine enters cells within the body, it uses this genetic code to produce the spike protein on the surface of the coronavirus. This induces an immune response, preparing the immune system to attack the coronavirus when it infects the body.
Among the most advanced candidates are also:
- CoronaVac, an inactivated vaccine from the Chinese biopharmaceutical company Sinovac developed in collaboration with the Brazilian research center Butantan.
- The Ad5-nCoV vaccine, developed by the Beijing Institute of Biotechnology (China) and the Chinese biopharmaceutical company CanSino Biologics and based on a non-replicating adenovirus type 5 (Ad5).
- Moderna Therapeutics mRNA-1273 vaccine based on the injection of fragments of the genetic material of a virus (mRNA).
- The BNT162b2 vaccine from Pfizer and BioNTech also based on mRNA technology.
The promising JNJ-78436735
On the other hand, on September 23, 2020, the Johnson & Johnson company announced that its candidate vaccine JNJ-78436735, developed by Janssen Pharmaceutical Companies, had started the Phase III large-scale and multi-country trial (ENSEMBLE). Candidate JNJ-78436735 is a monovalent vaccine composed of a recombinant, replication-incompetent adenovirus serotype 26 (Ad26) vector constructed to encode the spicular protein (S) of the SARS-CoV-2 coronavirus.
At this point, it should be noted that adenovirus (Ad) viral vectors have shown efficacy in preclinical and clinical trials against many important infectious diseases such as influenza or Ebola.
Traditionally, adenovirus type 5 (Ad5) has been the most widely used Ad vector. However, the high levels of pre-existing immunity to Ad5 have led to the development of alternative Ad vectors based on animal adenoviruses or low seroprevalence human adenoviruses such as Ad2 and Ad26.
In general, the scientific community has high expectations for vaccines based on adenovirus vectors. Both because of their great potential and because the technology necessary to manufacture them is available and could ensure a high production capacity.
In this sense, on July 1, the European Commission authorized the marketing of a new Ebola vaccine manufactured by the company Janssen Pharmaceutica. The vaccine requires two doses and consists of two components Zabdeno® (Ad26.ZEBOV) which is based on a non-replicating adenovirus serotype 26 and Mvabea® (MVA-BN-Filo) based on a poxvirus also without replication capacity.
The ideal vaccine with which we fight COVID-19 should be effective with one or two doses, protect population groups at risk, reduce community transmission and generate long-lasting immunity for at least 6 months. In addition to being capable of being produced on a large scale in a short time and at an affordable cost.
Ultimately, the vaccine candidates are multiple and promising. But development must be seen as a collective mission and not as a competition. Of course, the balance between speed, security and accessibility must be demanding and exquisite.
Raúl Rivas González, Professor of Microbiology, University of Salamanca
This article was originally published on The Conversation. Read the original.
