Pfizer Moderna data fails offering asymptomatics information effectiveness, a key group to curb the pandemic: In the last two weeks, Moderna and Pfizer have announced preliminary results of the last phase of clinical trials of their experimental vaccines against coronavirus and assure that they reveal an efficacy greater than 94%.

Although the news has been welcomed with optimism by all experts, who assure that it exceeds expectations and offers hope to the rest of vaccines, all call for caution until the phase is completed and the results are published in a scientific journal.

"The press releases communicate a preliminary result because the phases are not completed," warns researcher Mercedes Jiménez Sarmiento, a scientist at the Margarita Salas Biological Research Center (CIB Margarita Salas) of the Superior Council of Scientific Research (CSIC), in an interview with Business Insider Spain.

The scientist recalls that it is the health authorities who will approve the use of the vaccine and will do so by analyzing the data that have not yet been made public.

"It had never happened to us that we knew the results through press releases," acknowledges Jiménez, who points out that the companies "are moving tab on the economic and relevance board."

However, the expert does not deny that the data are hopeful and assures that "we are very close to having a vaccine", but points out that, "at the moment, there is a lack of data".

Jiménez Sarmiento explains that the tests carried out by Pfizer and Moderna are "double-blind". That is, those in which there is a placebo control arm and in which neither the participants of the trial nor the organizers know who is receiving the vaccine or not.

Pfizer Moderna data fails offering asymptomatics information

Volunteers are asked to live normal lives and only when they have been infected is it checked whether they have received the placebo or the vaccine.

"Following that design, companies have observed that the vast majority of coronavirus cases had not received the vaccine," explains the researcher.

"The first primary objective analysis is based on 170 cases of COVID-19, as specified in the study protocol, of which 162 cases of COVID-19 were observed in the placebo group versus 8 cases in the BNT162b2 group," Pfizer explains in its statement.

However, there is one small detail that prevents drawing conclusions about the real ability of vaccines to curb the pandemic: their effectiveness is unknown among asymptomatics.

"Effectiveness will be assessed throughout the participant's participation in the study by monitoring possible COVID-19 cases. If, at any time, a participant develops an acute respiratory disease, for the purposes of the study they will be considered to potentially have COVID-19 disease," explains the design of the Pfizer study.

It is in that case when the patient will be performed a diagnostic test that confirms or rules out the presence of COVID-19. That is, confirmed cases of coronavirus have only included symptomatic patients, but asymptomatic ones have been shown to play an important role in the spread of the virus.

With the data revealed so far, it is not possible to know how effective the vaccine is when it comes to preventing also asymptomatic cases, explains the Spanish researcher.

"Efficacy figures are measured for symptomatic coronavirus cases. Participants in the vaccine trial are not taken at regular intervals to check if they have tested positive, even if they are symptomatic, " also warns Science expert Derek Lowe. "We can get controlled data of that kind eventually," Lowe assures, but they have not yet been offered.

Mercedes Jiménez Sarmiento also asks himself another question. "Does the vaccine eliminate the ability to transmit?", reflect. The expert points out that a vaccine should serve to defend against the virus, but it will be even more useful if it slows transmission.

"If people continue to infect, the effectiveness of the vaccine decreases," warns Jimenez.

The expert believes that regulatory authorities will take into account this type of variables, so they will not prevent the arrival of the vaccine on the market, but it could happen that a vaccine was approved only for a collective.

"Not all of them have studied how it affects different groups," the researcher exemplifies. If a vaccine has not been experimented on in the older population or in children, it could be approved without being allowed to be administered to that group.

"Approximately 42% of global participants and 30% of U.S. participants have diverse racial and ethnic backgrounds, and 41% of global participants and 45% of U.S. participants are between 56 and 85 years old," Pfizer notes in its essay.

Recently, the company has also begun recruiting children from the age of 12 to gather data on how it affects them.

"There will be several vaccines," says the researcher optimistically, who is confident that the manufacturing and distribution challenges can be solved, since many companies have already started working on it.

Pfizer Moderna data fails offering asymptomatics information

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