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Vaccines, there is a problem on the horizon. And it doesn’t seem like a trivial matter at all. In about two months, perhaps March 1, Pfizer will also administer the vaccine to volunteers who were injected with placebo during the trial. A gesture of attention that may seem right, but it is not. Or at least, science is not usually like that. In fact, if there is no (and apparently there will not be) a suitable control group, the vaccine trial (which was supposed to end in two years) will end almost immediately. Outcome? We will not have certain data on the duration of immunity guaranteed by the Covid vaccine. Without the placebo group, there will be no benchmark for studying long-term efficacy and possible adverse reactions.
The Covid vaccine to the volunteers who had taken the placebo.
But Pfizer’s is not an isolated decision. In fact, Moderna also seems willing to follow the same path. The US FDA, the US government body that regulates food and pharmaceuticals, under the Department of Health, for the application of an emergency authorization, theoretically states that the manufacturer has a plan to carry out the trial. So he proposed to Pfizer and Moderna a way to extend testing without putting volunteers at risk. It’s called “blind crossing.” But the companies would have already taken another path, considering that the double-blind crossover study was not practical.
In a double-blind crossover study, participants receive a real treatment or a placebo for a set period of time, then switch over (“crossover”) to the opposite treatment. Thus, researchers can get twice as many participants: each person receives both the placebo and the treatment. The advantage of a cross match is that it effectively doubles the number of people in a test. This makes it easier for researchers to achieve statistically significant results.
However, there are also some major drawbacks to crossmatching. For example, people who receive a real treatment before the placebo can transfer their benefits to the placebo period, through the persistent and effective action of the treatment. Also, for various reasons, the longer a person participates in a study, the better the results, regardless of the treatment used. This tends to make the second treatment used in a crossover study seem more effective than the first. These effects, as well as others, act as confounders and make the crossover design less reliable (and less used) than the standard parallel group design.
In medicine, the most reliable answers come from double-blind, placebo-controlled studies. This means that patients are randomly assigned to receive treatment, in this case a vaccine or a placebo. Neither they nor their doctor know what they received. In many studies, such as cancer studies, it is simply assumed that patients who have received the placebo will receive treatment after the study ends. This step is known as a crossover.
But the question of how to handle the placebo crossover during a pandemic remained open as vaccine development accelerated. The consent forms provided to the volunteers, obtained from the industry site Statnews.com, did not mention when or if those who received the placebo would receive the two-dose vaccine.
Michael Tovar, a volunteer, had publicly asked Pfizer to offer the vaccine more quickly to all participants in the clinical trial that involved 44,000 people. After learning that everyone will get the “real” vaccine, he thanked the company and its CEO on Twitter. “Thank you for listening and for changing the study protocol to allow for rapid vaccination. You have made this new year so much brighter for the 22,000 volunteers who received placebo who have come forward to receive this vaccine.”
The same had happened with the now famous remdesivir: the drug had obtained an emergency authorization and the trial had been interrupted to administer the drug to all patients. What will be done in practice to scientifically evaluate the duration of immunity guaranteed by the vaccine? In Italy, Aifa will measure the amount of antibodies (immunogenicity) in a sample of people vaccinated for 12 months. In this way, however, immunogenicity is measured with a phase 2 assay, not 3. It should be emphasized that being protected means “not getting sick”, not “having antibodies”. In theory, protection against Covid could last even longer than antibodies. Or on the contrary, in the case of large mutations in the virus, as the journalist Andrea Capocci explains on Twitter, one of the first to focus on this issue.
So the vaccine will prevent transmission of the virus between vaccinated and unvaccinated subjects? Today we do not know. We have learned in recent months that even asymptomatic people transmit the virus. Thus? we await more data from ongoing clinical trials and we expect immunity to be total (sterilizing). There are still several unanswered questions regarding vaccines developed over the past year. However, conducting the trials in volunteers who were injected with placebo during the tests would be important in any case. According to someone very important. Will Clinical Trials Really End Before Time?
The Scientific Committee for post-marketing surveillance of Covid19 vaccines (CSV-Covid19), established on December 14, 2020 by the Italian Medicines Agency in agreement with the Ministry of Health and the Extraordinary Commissioner for the Covid-19 emergency, has been met for the first time on December 15, 2020, for the start of the works. The CSV-Covid19, which belongs to the General Directorate of the AIFA, will remain in office for two years and may be renewed based on the evolution of the pandemic and the progress of the Covid-19 vaccination campaign.
“This Scientific Committee represents a point of reference for the National Health System to guarantee active surveillance of the safety of all Covid-19 vaccines that will arrive in Italy. Composed of high-profile experts and proven scientific independence, it will guarantee transparent judgments about the total safety of all new vaccines and full compliance with the protocols followed in the vaccination campaign. CSV-Covid19 will help strengthen Italy as an authorized member of the global research community, ”said AIFA Director General Nicola Magrini.
As for Europe, EMA (the European Union Agency for the Evaluation of Medicinal Products) believes that there should be data on efficacy after “conditional” marketing authorization. In a few days it will consider Moderna’s request for its vaccine, which has already announced that it will give the vaccine to the placebo group. It is not known what decision will be made.
Vaccines: what we know about immunity
According to Guido Rasi, professor of Microbiology at the University of Rome Tor Vergata and former executive director of the European Medicines Agency (Ema), regarding the duration of immunity to vaccines, “we expect it to last at least 9-12 months “, the actual observations are so far 6 months. For now they are all hypotheses, a close and timely follow-up campaign is also essential to see the differences between the different vaccines and do many tests in people because the variants are beginning to exist.
If the duration of immunity is uncertain, many wonder when immunity begins after administration of the vaccine. “Already after the first administration of the vaccine” you have a first immunity “, but anyway it will take a few days. Under natural conditions, the antibodies are at a reasonable titer after about ten days from the onset of symptoms “, explained recently Massimo Galli, director of the department of infectious diseases of the Sacco hospital in Milan.” A vaccine generally forces the physicist to respond A more powerful, effective and immediate immune response than a natural infection, so we should have an immune response data from the first available vaccine – he says – tell us that vaccinated people have been protected from the beginning. The number of cases of infection in the first 21 days after vaccination is already significantly lower than in the placebo group “.
Coronavirus, WHO approves emergency use of Pfizer vaccine
The World Health Organization has approved the emergency use of the Pfizer / BioNTech coronavirus vaccine, paving the way for poor or developing countries that do not have their own pharmaceutical regulatory authority to use the drug for population immunization.
The vaccine was approved for emergency use on December 8 in the United States, closely followed by Canada and the European Union. The WHO green light states that the vaccine is safe and even countries that cannot provide national approval for the drug can use it. The WHO added in a statement that the Pan American Health Organization and UNICEF can now provide doses for the vaccine to be distributed in countries that need it.
In this direction it is possible to know in real time (more or less …) how many Italians are vaccinated against Covid.
