On Monday, November 9th, Pfizer announced that early data from its coronavirus vaccine trial suggest that the vaccine is more than 90% effective in preventing COVID-19. Pfizer’s phase 3 clinical trial that enrolled 43,538 participants who were split into two groups: a group that received the vaccine and a placebo group. Since the phase 3 trial began in July, there were 94 confirmed cases of COVID-19 and less than 10% of these cases were individuals who received the vaccine.
While this is relatively early data and long-term safety and efficacy data will still need to be collected, this is a promising development for a number of reasons, particularly because scientists were hopeful for 50-60% effective vaccines.
How does Pfizer’s vaccine work? Pfizer’s vaccine contains virus messenger RNA, or genetic material that carries information between different parts of a cell. This vaccine uses messenger RNA that describes one of the now infamous spike proteins that cover the outer surface of SARS-CoV-2. Although human cells don’t make spike proteins, they can still read the viral messenger RNA and follow the instructions to create the spike protein. Because these are foreign to human cells, the presence of the proteins causes the immune system to respond and eliminate the spike protein. This response caused by the vaccine prepares the immune system to respond should an individual become exposed to the virus.
With that said, the next challenge is production and distribution. Pfizer has said it can produce 50 million doses available by the end of the year and 1.3 billion doses by the end of 2021. This is a two dose vaccine, which means that based on these estimates, there could be enough doses for 25 million people around the world available by January. Additionally, scientists believe that a number of other vaccines currently in development will become available in the coming months.
One logistical concern is that Pfizer’s vaccine needs to be stored at the extremely low temperatures of -80 degrees Celsius (-112 degrees Fahrenheit). Freezers that cool to this temperature are found in biomedical research laboratories but not your standard doctor’s office or pharmacy. Other vaccines currently in development require less extreme temperatures, which could make vaccinating certain populations easier. Additionally, this vaccine will be a two-dose vaccine, which will add additional logistical complexity.
Who will get the vaccine first? The National Academy of Medicine places those at highest risk from the virus at the top of the list and breaks down distribution into five phases:
Phase 1a: Front-line health workers
Phase 1b: Individuals with underlying conditions that put them at significantly higher risk
Phase 2: Critical workers in high-risk situations including teachers and childcare workers and individuals with underlying conditions that put them at moderately higher risk
Phase 3: Young adults, children, and people who work in industries such as hotels, banks, and factories
Phase 4: Everyone else
With widespread vaccine distribution still many months away, experts emphasize the importance of taking measures to control the spread of COVID-19 now.
Until next time, stay vigilant, and let's do everything we can to stop the spread.
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