Development time does not have to be detrimental to vaccine safety

For a vaccine or any other medicine to be approved, it must have been shown to be safe and effective


A thread ensuring that “it is absolutely impossible” to have a safety vaccine developed in less than eight years is circulating these weeks in WhatsApp. This is FALSE: for a vaccine or any other medicine to be approved, it must have been shown to be safe and effective. For this purpose, clinical trials are carried out, comprising several phases (phase I, phase II, phase III…).

“It is absolutely impossible for a vaccine to be safe if the timing for it to be safe (about 8 years) has not been respected”

Vaccines against covid-19 have been the fastest in development in history because not only the necessary economical resources have been obtained, coming from both public and private funds, much fastest as usual, but also an unprecedented international effort has been done to share the knowledge between countries and publish the data of the studies in open source.

Overlapped phases

In addition, the different phases of the clinical trials have been greatly streamlined: they were overlapped with each other to save time; in those cases in which the results were satisfactory, the distribution of the vaccine in the population was possible to be approved. Together with this, one has to take into account that most of the vaccines, specifically those of mRNA, which are those that had not been used before with humans, already counted with a previous development, that is, that it was not started from zero: “Behind these vaccines there is a work of several decades which allowed that they were 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 election for the vaccines, and that a two aminoacid substitution in its sequence made it further stable”. In fact, this super-stable version is the one used by Moderna, Pfizer, Novavax and Jannsen vaccines.

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) and are the fastest to be produced once the virus is sequenced and it is known which is the protein wanted to be used as antigen”. In this case, she concludes, “it was already known that it was the Spike protein”.