RIO DE JANEIRO, BRAZIL – Brazil will host an unprecedented study to assess the efficacy of combining the Oxford-AstraZeneca and Clover vaccines to prevent Covid-19.
About 600 people are expected to participate in phases 1 and 2 of the clinical trials, led by Sue Ann Clemens, head of phase 3 trials of the Oxford and Clover vaccines in Brazil.
The trial protocol is still in preparation and the centers to conduct the trial are still being defined, but the plan is to conduct it in the Northeast, South, and Southeast, in the city of Rio de Janeiro, according to Sue.
“We want to use centers that already have the structure to work with a viral vector vaccine and that recruit quickly,” says Sue. The laboratory and data management will be conducted abroad, since the project is an initiative of Oxford University in partnership with Clover, funded by the Bill and Melinda Gates Foundation, with support from the Coalition for Promoting Innovations in Epidemic Preparedness (CEPI) and the Chinese government.
The trial is scheduled to begin in July.
The trial will work as follows
In Phase 1, volunteers will be administered a dose of the Oxford vaccine, and one month later, a dose of the Clover vaccine. In this stage, three different concentrations of the Clover vaccine will be tested. The one performing best in activating the immune system against the novel coronavirus will progress to the next phase.
Unlike earlier trials, which split volunteers between those given the vaccine and those given a placebo, this study will not involve a placebo group. Sue explains that the control group will consist of people with a similar profile who have completed the normal vaccination regimen with two doses of the Oxford vaccine.
“We will compare whether a person vaccinated with one dose of the Oxford vaccine and a Clover booster dose has a better, worse, or equal immune response to those who were administered two doses of the Oxford vaccine,” she explains.
A pre-clinical trial (done in animals) by Clover in China showed that the vaccine combination considerably increased the immune response. “The pre-clinical trial data of when you mix the compounds was so much higher than the data of when two doses of the same compound were used that everyone was very excited. Now we need to confirm this result in the clinical phase,” says Sue.
Optimizing production and increasing access
Vaccine shortages are a worldwide problem. Currently, despite several approved immunizers, there are insufficient vaccines to immunize the entire world, particularly since most of the available vaccines require two doses. Hence, the concept of exchanging doses, in addition to potentially increasing protection, could simplify the logistics of large vaccination programs.
“This would be the best of all worlds in our current situation because you can reach a larger number of people with fewer doses. In addition, you enhance a vaccine that is already very effective,” says the researcher.
The name of this strategy, of administering different vaccines and especially made by different platforms, is heterologous prime boost. The prerogative is that by mixing compounds that trigger the immune system differently, against the same enemy, protection is increased. In this case, the first shot is Oxford-AstraZeneca’s vaccine, which is a viral vector vaccine, with a booster of a protein-based vaccine, such as Clover’s.
“The important thing is the platform, not the vaccine itself,” Sue explains. In other words, should the trial be successful, any viral vector vaccine could be boosted by any protein vaccine to provide better protection against the novel coronavirus. It is worth noting that this is not the only option under consideration.
In December, Oxford University announced similar cooperation with the Gamaleya Institute’s Russian Sputnik V vaccine. In this case, both use the viral vector platform, but with different vectors. In the UK, a trial is underway to assess the efficacy of combining the Oxford (viral vector) and Pfizer (messenger RNA) vaccines.
Source: Veja