Pfizer’s new antiviral, the fourth phase III trial for a SARS-CoV-2 vaccine begins, and NIH expansion of convalescent plasma trials for COVID-19

There have been many advances in clinical trials over the past two weeks. The first large announcement is Pfizer’s antiviral, PF-07304814, is entering phase I trials (NCT04535167). This antiviral was originally developed in the SARS-CoV-1 outbreak, but was ended prematurely in trials due to a lack of demand. However, Pfizer has reported in a pre-print that the antiviral has efficacy across multiple coronaviruses including SARS-CoV-2, although this pre-print has yet to withstand peer review (Boras B, et al. 2020 ). With Remdesivir being the only antiviral to demonstrate efficacy in SARS-CoV-2 infection so far, it will be interesting to see how it compares to other emerging antivirals, and if the therapies can be used in combination for improved clinical outcomes.

Another exciting development in the past week is the start of the fourth phase III vaccine trial for SARS-CoV-2 (ENSEMBLE). Johnson & Johnson has entered their final stage of vaccine development and are planning to recruit 60,000 participants for this phase. It is interesting to note that this vaccine has a single dose regimen compared to the other vaccines in US phase III trials that use a  two dose regimen spaced ~3 weeks apart. This decision came from the results of the phase 1b/2 trial in which one and two dose regimens were compared. Another key difference of this vaccine compared to the frontline mRNA vaccines, is that it is stable at 4-8 C (39.2-46.4 F) for 3 months (and up to two years at -20 C). Both the easier storage and one time dosing would allow for much easier distribution to the population.

The NIH has also announced planned expansion of convalescent plasma trials by the inclusion of more sites in its ongoing studies. Recently, convalescent plasma has received an emergency use authorization (EUA) from the Food and Drug Administration. However, this decision garnered a lot of controversy, including from the NIH. In response, the NIH is now expanding their efforts to study convalescent plasma as many questions remain about the therapy (for more information, check out our posts from Sept 2nd and 7th).