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Latest Updates on Vaccine Development & Distribution Plan

California reported a total of 14,034 new cases yesterday, a 1.2% increase from the prior day total. Orange County's rate of daily cases has passed the summer highs just this Monday. As the number of daily cases and hospitalization surge at a devastating rate entering the holidays, recent developments in vaccines shed light on the possibility of returning to life before the pandemic.


Latest Updates on Vaccine Development and Allocation.


There are currently three vaccines with encouraging results in their phase III clinical trials. On November 9th, Pfizer announced their vaccine candidate is more than 90% effective in clinical trials. Exactly one week after Pfizer's announcement, Moderna's vaccine is reported to be 95% effective. On November 20th, Pfizer filed for FDA's emergency use authorization, kicking start an accelerated process that could begin vaccination by the middle of December. AstraZeneca revealed that their vaccine candidate, developed by Oxford University, is 90% effective in its phase III clinical trials and has applied for an emergency authorization just this Monday. The federal government projects to have 40 million doses of vaccines from Pfizer and Moderna, enough to vaccinate 20 million people, by the end of 2020. The government plans to send the first 6.4 million doses of Pfizer's vaccine to communities across the U.S within 24 hours of regulatory clearance. The allocation of the first patch of the vaccine will be based on the state's total population, with front-line health-care workers having the highest priority of vaccination. Dr. Anthony Fauci projected the general public could get their first dose as early as April.



Key Differences between Pfizer, Moderna, and AstraZeneca vaccines.


The three vaccine candidates for distribution are Pfizer, Moderna mRNA vaccines, and AstraZeneca's viral vector vaccine. Because of their different approaches, the vaccines have specific storage and transportation requirements that set them apart.


While AstraZeneca is a viral vector vaccine, Pfizer and Moderna's vaccines are both mRNA vaccines. A conventional vaccine contains weakened or inactive parts of the pathogen (antigens). After injection, the body recognizes, registers the injected antigen as a thread and develops antibodies and immune cells against the virus without provoking a full immune response. The three vaccines follow the same principle explained above but utilize two different approaches. Instead of injecting a weakened or inactive part of the pathogen (antigen), Pfizer and Moderna vaccines introduce an mRNA sequence, which acts as a set of instructions for cells to produce the signature spike protein found on the Coronavirus. AstraZeneca uses the genetically altered Chimpanzees virus as a vehicle to deliver the DNA instruction coded for spike proteins to host cells.


Because of mRNA instability, Moderna & Pfizer vaccines need to be stored and shipped at low temperatures. The Moderna vaccine is stored frozen at minus-20 degrees Celsius and can be kept for a month at refrigerator temperature. The Pfizer vaccine must be kept at ultracold (minus-70 degrees Celsius). To solve the shipping issue, the company has created its GPS tracked cooler filled with dry ice to distribute its vaccine. On the other hand, the AstraZeneca vaccine can be stored at refrigeration temperatures for up to 6 months, making it the best candidate for mass distribution in much of the world. However, AstraZeneca has not yet requested emergency FDA authorization.


Source: Advisory Committee on Immunization Practices (ACIP) Meeting Presentation https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2020-08/COVID-08-Dooling.pdf



Three Phases of Vaccine Distribution in Orange County

The U.S will likely start vaccination using both Pfizer and Moderna vaccines once they arrive. With the vaccines soon to be delivered, the challenges lie in funding, public skepticism, and equitable distribution. The OC Health Care Agency has established a Vaccine Taskforce leading the effort in planning for equitable vaccine distribution. The county distribution plan will follow the CDC phased approach.

According to the CDC recommendations, the first phase of vaccine distribution consists of three subgroups (Phase 1a, 1b & 1c). Health care workers and long term care facility residents will be the first in line to receive the vaccine (Phase 1a). Essential workers will be the second group to receive the vaccine (Phase 1b). High-risk individuals due to underlying medical conditions, people 65 years and older make up the last group of phase I. Vaccine administration during phase 1 will be highly targeted due to limited supply. When there is sufficient supply to meet demand, vaccine administration in Phase II and III will broaden vaccine administration and focus on increasing access to critical populations and the general population.



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