The FDA’s latest EUA for Convalescent Plasma, AstraZeneca’s new antibody cocktail, and new mRNA vaccine storage details

The FDA has now given an emergency use authorization (EUA) to the use of convalescent plasma in treating severe COVID-19. Convalescent plasma contains antibodies from patients who have recovered from COVID-19 and is a common therapy tested in any novel infection. However, convalescent plasma has many limitations that monoclonal antibodies seek to solve (check out the post from two weeks ago!).

The EUA came on the heels of a pre-print article that followed 35,322 patients who received convalescent plasma therapy across the US (Joyner MJ et al., 2020). However, the data and paper have yet to withstand peer review, and there has been debate in the field on the effectiveness due to the overall lack of data at this point. In addition, this retrospective study is not the ideal double-blinded trial that would better determine safety and efficacy. While this EUA acts as an attempt to quickly bandage the problem, there still is more testing and development that needs to be done to improve antibody therapies in COVID-19.

On the front of other antibody therapies, AstraZeneca announced last week that they would begin phase I trials of their double monoclonal antibody cocktail AZD7442. The two antibodies in the therapy were recovered from COVID-19 patients with some modification to improve efficacy. Previously, they had released a paper in Nature on the efficacy of the antibodies in animal models and in cell lines. One unique aspect of this trial is that AstraZeneca is testing both intravenous and intramuscular injections. Typically, antibody trials focus on intravenous distribution, but this limits the therapies to hospitals and specific clinics that have the means to provide such a therapy. If the intramuscular injections are equally effective for this therapy, it could widen the range of locations in which it could be used.

Last week, there was also the release of mRNA vaccine transportation and storage details from the frontline vaccine developers Moderna and Pfizer. While mRNA vaccines are easily rapidly produced from the time of virus sequencing, there are several drawbacks to the vaccine design with the top one being shelf-life and stability. mRNA is a complex molecule that is unstable at room temperature for long periods of time. Moderna and Pfizer/BioNTech confirmed their vaccines would need to be stored and transported at -20℃ (-4℉) and -70℃ (-94℉) respectively. Not all pharmacies have freezers, much less to store potentially hundreds of vaccine doses. However, the Moderna and Pfizer/BioNTech vaccine can respectively stay at 2-8℃ for 7 days and 24 hours immediately prior to use. As the US has already committed to 100 million vaccines from each manufacturer, the distribution plans need to begin planning for the mass amounts of cold storage needed at different vaccine distribution hubs. In an effort to quickly disperse the vaccines, the availability of appropriate freezer storage may be a limitation to wide spread distribution.

References

Joyner MJ, et al. (2020) Effect of Convalescent Plasma on Mortality among Hospitalized Patients with COVID-19: Initial Three-Month Experience. medRxiv:2020.08.12.20169359.

 


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