By Carmen Álvarez Domínguez - The Conversation
Biochemist and molecular biologist, professor of Health Processes at the Faculty of Education and researcher in Immunotherapy, UNIR - International University of La Rioja
Between two and four years.
That is the time it usually takes to prepare a new vaccine such as the SARS-CoV-2 virus, responsible for the COVID-19 pandemic.
During that time, multiple clinical trials are conducted with a high number of healthy volunteers.
And the vaccine is only considered suitable if good results are achieved in three consecutive phases in which its safety, efficacy and effectiveness are examined to provide long-lasting immunity, that is, to protect from the infectious agent for a long time (or a lifetime).
The question that surrounds us all is,
can the process be shortened?
Yes, partially overlapping the three phases in time.
But never below 18 months.
Which in the case of COVID-19 implies waiting for the spring of 2021.
The three phases of the trials
The first phase of a clinical trial of a vaccine examines whether it induces fatal toxicities or serious pathologies in twenty to one hundred healthy volunteers recruited.
This phase usually takes at least three months.
A second phase follows in which the immune response against the infectious agent, the doses of the vaccine and the vaccination schedule are evaluated.
For this, between 200 and 500 volunteers are recruited.
Normally, in this second phase we work with adult volunteers between 18 and 55 years old, healthy, who have not passed the infection.
And in the case of the current COVID-19 pandemic, as the elderly are the most vulnerable, a group of healthy individuals over 65 is included.
Between two and four years.
That is the time it usually takes to prepare a new vaccine such as the SARS-CoV-2 virus, responsible for the COVID-19 pandemic.
AP
In both groups of volunteers the complete vaccine is tested.
But half of them, chosen at random, are injected with “placebo” instead of the complete vaccine, that is, the formulation of the vaccine without the antigen of the pathogen responsible for the immune response.
[A Latino is the first to receive proof of a vaccine against COVID-19 developed by AztraZeneca]
It is desirable for volunteers to live with the infectious agent to examine whether the vaccine can protect against infection.
In the case of the current SARS-CoV-2 virus situation, there are countries in the first wave of infection and others in the second wave.
This second phase of trials usually lasts at least six months.
Phase three aims to
check the long-term immune response.
In this phase, thousands of volunteers are recruited, usually between thirty and fifty thousand people, with the same characteristics and groups as in the previous phase.
That is, be healthy and have not passed the infection.
By including a very high number of volunteers, this phase has great statistical value, both for detecting secondary toxicities, which would have gone unnoticed in the previous phase and which are never serious but mild toxicities, and for establishing the efficacy of the vaccine.
Normally it is required that it be higher than 60%, although in the case of COVID-19 the WHO proposes to require only a minimum of 30%, and consider 50% suitable.
This phase usually has a minimum duration of six months, although the most common are nine or more.
Taking into account all these phases, the minimum trial time is 15 to 18 months.
Are the announcements of a vaccine for November realistic?
Would it then be possible to have the first vaccine against COVID-19 for October or November, as has already been heard in different media?
If we stick to the necessary phases for approval, no.
Demand for Flu Vaccines Increases in Mexico Amid Coronavirus Pandemic
Oct. 15, 202002: 06
But it is not recommended either.
Among other things, because not only do these phases have to be met, but also the final evaluation of the results of the last phase by the regulatory agencies and the monitoring of vaccinated individuals must be taken into account.
To top it all, once it is approved, it takes some time to produce the vaccine, pass it through quality controls and detect possible side effects.
[This controversial coronavirus vaccine trial uses healthy volunteers infected with COVID-19]
In the case of the possible vaccine for SARS-CoV-2, to have global coverage with a very high number of doses, it would be necessary to add at least three more months.
Although there are already companies that are starting to manufacture it before it goes through all the tests successfully, what if all goes well could also speed up the process.
Therefore, if all goes well with the current phase III vaccines for the COVID-19 pandemic, the most likely dates would be from January or February next year.
The downsides of rushing
Can rushed trials affect its effectiveness?
If these reasonable timelines of the three complete phases of clinical trials for the preparation of a vaccine are not followed, it is
very possible that the efficacy will be affected, which discriminates the results between vaccinated and unvaccinated individuals.
At this point, it is convenient to clarify the differences between efficiency and efficacy of a vaccine:
The
efficacy
of a vaccine is the percentage reduction in the incidence of an infectious disease in vaccinated individuals versus the group of individuals who are not vaccinated (placebo group).
It is measured in the third phase of the design of a vaccine.
The
effectiveness
is the ability of a vaccine to protect against infection when applied in real conditions, which is assessed upon completion of
clinical trials, with all its phases.
That is, it is the evaluation that is made once it is marketed.
Which is also important.
In addition, the rush could prevent an evaluation of why sufficient protection is not achieved in some subjects, if there is a genetic reason for this, or if the vaccine formulation can be modulated to achieve universal adequate protection.
CVS pharmacies want to hire 15,000 people in the face of the development of the pandemic and vaccination plans
Oct. 20, 202000: 22
By speeding up the process,
neither the secondary toxicities nor the scientific reasons for these toxicities can be well evaluated.
The latter would be especially important for individuals with certain pathologies (diabetes, severe chronic or respiratory cardiovascular diseases or cancer), which in the case of the SARS-CoV-2 virus are high risk and candidates for vaccination in the early stages.
[California will independently review the COVID-19 vaccine prior to distribution]
In summary, the times to prepare a vaccine against an infectious agent that poses a great global challenge can be shortened.
But always within limits that do not determine the efficacy, effectiveness, or safety of all possible candidates for vaccination.
Carmen Álvarez Domínguez is a biochemist, molecular biologist and professor of Health Processes at the Faculty of Education and researcher in Immunotherapy, UNIR - International University of La Rioja.
This article was originally published on The Conversation, under the Creative Commons license. Read the original article here