At the beginning of 2020, when scientists started their search for a vaccine against the SARS-CoV-2 coronavirus, the development time was estimated to 12 - 18 months minimum.
Before the vaccine against COVID-19, no vaccine against any infectious disease had been produced in less than several years, in addition, there was no vaccine preventing any disease caused by human coronaviruses at all. Since 2003, however, some vaccines against diseases caused by animal coronaviruses have been produced, including those against avian infectious bronchitis, canine, and feline coronavirus disease. The objective of the previous projects (from 2005 and 2006), which focused on development of vaccines against viruses from the Coronaviridae family attacking humans, was to develop a vaccine against the severe acute respiratory syndrome (SARS) and the Middle East respiratory syndrome (MERS). These vaccines had been tested on animals. Although their development had not been finished, experiences gained from it could be used in the development of the vaccine against SARS-CoV-2.
The urgency to create a vaccine against COVID-19 led to setting up accelerated harmonograms which let the common development timespan of a vaccine shrink to months.
The fastest development of a vaccine so far - from picking the virus, in this case the mumps one, to the final approval - lasted 4 years. That vaccine had been developed in the sixties. But already at the beginning of December 2020, developers of several vaccines had announced excellent results of their big trials. And on December 2, 2020, the vaccine produced by the Pfizer big pharma and German bio-technological company BioNTech became the first fully tested and (emergency-use-)authorized vaccine against SARS-CoV-2 coronavirus.
Even with its development so accelerated, a vaccine has to succesfully pass the following series of clinical trials:
Phase I - the safety of the vaccine as well as its ability to trigger an immune response gets evaluated on a small group of people
Phase II - in this phase the effective dosis is determined, the vaccine is tested on a greater group of people now
Phase III - the sample group of people grows to thousands, the safety and efficacy of the vaccine is tested
Currently almost 200 vaccines are tested, of which 154 are vaccine candidates in a preclinical stage, 21 in Phase I, 12 in Phase II, and 11 in Phase III. The Pfizer/BioNTech and Moderna big trials had counted 44.000 and 30.000 volunteers, respectively. Half of them got a placebo - that is, compared to Phases III of other trials, significantly more. These numbers of volunteers participating are able to compensate the shortening of the monitoring period.
The experiences from the COVID-19 vaccine development almost certainly will change the future of the vaccine-related science. They show how fast the vaccine development can advance when there is a real global threat and enough resources. It turned out that it is possible to significantly accelerate the development process of a vaccine without violating its safety at the same time.
Original text author: prof. MUDr. Roman Prymula, CSc., Ph.D.