Salut, Covid-19, Vacunes

All the vaccines against covid-19 didn’t appear “suddenly” at the same time

A man who self-identifies as Mike Yeadon, a former Pfizer employee, comments on an interview on the podcast The Delingpod, that he has always found “an amazing coincidence” that no vaccines against coronavirus existed and that “suddently, we have three more or less similar ones, and all of them in few weeks”.

"Suddently, we have three more or less similar ones [vaccines], and all of them in a few weeks"

It is about a MISLEADING assertion, because while it is true that the first three vaccines (Pfizer, Moderna and AstraZeneca) where approved almost simultaneously between December and January, the number of authorised drugs has not stopped growing since then: in April we already have more than ten authorised by the regulatory agencies. On the other hand, there are still around 70 vaccines immersed in clinical trials, and up to 30 in the initial phase. That is, this is a misleading information because three were approved more or less at the same time, but the majority have not had the same luck.

Moreover, the fact that the first three vaccines were approved so quickly was not a matter of chance, but the results of years of study. For instance, those using messenger RNA have been studied “for about a decade”, as indicated by the World Health Organisation (WHO) in its website, and, in fact this technology has already been used in vaccines against “Zika virus, rabies and flu”.

Decades of work

In fact, the first clinical trials in which the inoculation of messenger RNA is conceived as a promising alternative date back to 1990, when mRNA genes were injected to mice and which results, published in the journal Science, indicated an increase in the production of proteins. Nonetheless, it is only in the last decade that more resources have really been invested in the development of mRNA as a therapeutic tool.

“There is decades of work behind these vaccines that allowed them to be developed so quickly”, points Adelaida Sarukhan, immunologist and scientific writer at ISGlobal. “Thanks to the studies with SARS and MERS, it was known that the Spike protein was the antigen of choice for vaccines, and that a two aminoacids substitution in its sequence made it even more stable”. In fact, this super-stable version is the one used by Moderna vaccines, Pfizer, Novavax and J&J.

Concerning the issue that several vaccines have been approved “almost at the same time”, as Yeadon states, the reason relien on the acceleration of the different phases of the clinical trails. Traditionally the development of a vaccine lasts for 10 years, but the emergency that covid-19 has involved, this process has been reduced by different manners.

Overlapped phases

For example, the different phases of the clinical trials were not performed one by one as usual —phase I firstp, then phase II, then phase III…—, overlapped with each other to save time; in those cases with satisfactory results , it was possible start approving the distribution of the vaccines in the population. In addition to this, we must take into account the huge investments both public and private that have made possible for pharmaceutical companies to have the enough resources in a sort time to carry the clinical trials out.

Moreover, as Sarukhan recalls, “it is not surprising that the first two vaccines that were approved did so almost at the same time (Pfizer and Moderna)”, since “both use the same technology (mRNA) are the fastest to produce once the sequence of the virus is known and the protein that will be used as antigen is also known”. In this case, concludes, “it was already known that it was the Spike protein”.

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Aquest article és part del projecte "Les Mentides Amenacen la Salut", el primer portal de fact-checking de rumors sobre la covid-19 de Catalunya.

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