Three of the nearly 200 vaccines being developed against coronavirus have entered phase III of the trials. What does this mean and how close are we to having one?
The key tool to relax containment measures and return to a state as close to normal as possible is a COVID-19 vaccine.
As the coronavirus began to spread rapidly around the world after the first cases appeared in the Chinese city of Wuhan in December 2019, efforts began to develop a vaccine to protect us from this. multisystemic disease.
How far have those efforts gone? Which vaccines have advanced the most in their development process? And when will they be available to immunize the population and protect it from SARS-CoV-2?
BBC Mundo reviews the most important advances.
Currently, there are about 200 groups working around the world in search of a vaccine, and the World Health Organization (WHO) is tracking about 140.
Of that total, 18 are being tested on humans in clinical trials.
And from 18, there are 3 that are more advanced: the experimental vaccine CansSino Biologics (China), the so-called ChAdOx1 nCoV-19 from the University of Oxford (United Kingdom), and the one developed by the company Moderna (United States).
Before looking at each one in more detail, let’s briefly recall what path a vaccine takes until it is approved.
First the preclinical phase, where its efficacy and tolerance in animals are tested. It is followed by phase I, where it is tested on a small group of humans (less than 100) to assess its safety and biological effects.
The inoculation then enters the phase II, where the group is largest (between 200 and 500) and where its effectiveness is also analyzed, until reaching the phase III, It incorporates many more participants (hundreds of thousands of people), and it is done in randomized and double blind tests, and it is compared against a placebo.
This means that, although a COVID-19 vaccine shows great promise in terms of safety and the immune response it generates in the early stages, it is not possible to know if it will help prevent infection or even reduce its symptoms until the third phase ends.
Because of the speed at which experimentation is taking place, some vaccines are going through a combination of phases simultaneously.
These are the three most advanced.
CanSino Biologics (China)
The Chinese company announced in July the start of phase III trials of its vaccine in Brazil.
The vaccine-baptized Ad5-nCoV– use another virus (a adenovirus of the common cold) to introduce into human cells the genetic information of the new coronavirus, with instructions to make some of its viral proteins and thus generate a immune response, but without developing the disease.
In late June, China approved its use for the soldiers of its army,
According to a statement from the company that published the results of its trials in the medical journal. The Lancet, the results of clinical trials “show a good profile in terms of their safety and high levels of immune response cellular and humoral ”.
“Overall clinical results indicate that Ad5-nCoV has the potential to prevent disease caused by SARS-CoV-2.”
The vaccine was tested in 508 participants
However, the same statement warns that there can be no guarantee that the vaccine will be successfully marketed.
The Chinese vaccine was the first in the world to enter phase II.
Still, testing on thousands of people is required to demonstrate its effectiveness.
Modern was the first company to test an experimental vaccine -called mRNA-1273- in humans.
As reported by the company in May, the vaccine had hinted that it could train the immune system to fight the coronavirus.
Modern noted that they had found neutralizing antibodies virus in the first eight people who participated in the study to assess safety.
They also said that the immune response had been similar to that of people infected with the virus.
The vaccine is a small snippet of the genetic code for coronavirus which is injected into the patient.
It does not cause infection or symptoms associated with COVID-19, but it has the ability to elicit a response from the immune system.
Study participants were given a low, medium, or high dose. The higher dose caused more side effects.
However, Moderna noted that those given the lowest dose produced the same level of antibodies detected in people recovered from COVID-19.
Those who received medium doses had “significantly more antibodies” than the recovered patients.
Other companies (BioNtech and Pfizer) also announced positive results using the same procedure for their vaccine.
Oxford University, ChAdOx1 nCoV-19 (UK)
The University of Oxford announced Monday that the vaccine it is developing proved to be safe, and that it generates antibodies and T cells to fight the coronavirus.
The result of the trials -in about 1,000 people- was rated as very promising, but, as mentioned above, its efficacy against the virus remains to be demonstrated in the next phase of the trial.
The vaccine was created from a genetically modified virus which causes the common cold in chimpanzees.
This was genetically modified so that it does not cause infections in humans to make it more similar to coronavirus.
The study showed that 90% of people developed neutralizing antibodies after a dose.
There were no dangerous reactions to the vaccine, although 70% developed fever or headachesymptoms that researchers say can be treated with paracetamol.
In the next stage, the trial will be expanded to over 10,000 people in the UK. 30,000 people will also participate in the US, 2,000 in South Africa and 5,000 in Brazil, where the number of infections is higher.
When will the first vaccine be ready?
The race to find a vaccine advances at lightning speed, researchers agree.
Typically, developing a vaccine takes years, if not decades. Scientists hope to get the same job done in a matter of months.
Most experts believe that we can probably have a vaccine available for the vast majority to mid 2021.
In other words, we would have it only a year or a year and a half after the SARS-CoV-2 first emerged.
If so, this would be a milestone in science, but we will have to see if it works.
A vast majority of experts believe that now is not about whether or not a vaccine can be found, but when.