(500 words, keywords: Covid-19, Pfizer, Moderna)
As of January 15, 2021, there are two Covid-19 vaccines approved by the U.S. Food and Drug Administration (FDA) for immediate emergency use in the United States. The Pfizer-BioNTech COVID-19 Vaccine (commonly referred to simply as the “Pfizer vaccine”) was approved for emergency distribution on December 11, 2020 for individuals 16 years and older. The Moderna Covid-19 vaccine was approved on December 18, 2020 for emergency distribution to individuals 18 and older.
In effectiveness trials, the Pfizer vaccine proved to be 95% effective in preventing Covid-19 among clinical trial participants, while the Moderna vaccine was deemed 94.1% effective.
In the Pfizer trials, only 1 of the 18,198 participants who received the vaccine contracted a case of the illness which could be classified as “severe.” Of the 14,134 participants in the Moderna trials, none of the individuals who received the vaccine and then contracted the illness were classified as severe cases.
Both vaccines carry potential side effects of pain at the injection site, tiredness, headache, muscle pain, chills, joint pain, and fever. Additional potential side effects listed for the Moderna vaccine include swollen lymph nodes near the injection site, as well as nausea and vomiting. Both vaccines require two doses and carry a greater potential for side effects after the second dose. The Pfizer vaccine requires a second booster dose 21 days after the original, while the Moderna vaccine’s booster dose is recommended 28 days after the original. The vaccines are not considered interchangeable at this time, meaning that the first dose of either vaccine should be followed with a second dose from the same manufacturer.
The Pfizer vaccine dosage is .3 mL whereas the Moderna dosage is .5 mL. While both vaccines require refrigeration and have limited viability once exposed, the Pfizer vaccine must be kept at extremely cold temperatures making its delivery to rural locations logistically less feasible than the Moderna vaccine.
Unlike older vaccines which rely on injection of dead or weakened virus cells, both the Pfizer and Moderna vaccines are categorized as Messenger RNA (mRNA) vaccines. Using a relatively new technology, mRNA vaccines use strands of genetic coding that activates inside the body to produce a partial protein unique to the virus, in this case Covid-19. When detected, cells produce relevant antibodies. Advantages of this type of vaccine include its non-infectious nature and a faster manufacture time. As development of this technology is ongoing, the Center for Disease Control (CDC) continues to monitor testing and developments in this field.
Because of the expedited timeline for emergency approval, neither of the current vaccines have been in trial long enough to evaluate the duration of protection. As such, the CDC does not recommend additional boosters beyond the first two recommended doses at this time. As trials continue, the CDC notes that this and other recommendations may change.
Trials for at least three other vaccines are currently underway in the U.S. including AstraZeneca, Jansseen (Johnson and Johnson), and Novavax.
Detailed information can be found on the CDC website at http://cdc.gov and the FDA website at http://www. fda.gov.