Pfizer-BioNTech COVID-19 Vaccine Fast Facts

Fast facts about the Pfizer-BioNTech COVID-19 Vaccine

  • The vaccine is given in 2 doses 21 days apart.
  • The vaccine needs to be stored and transported at -80C/-112F. It can be kept at regular refrigeration temperatures for only 5 days. This is likely to be a barrier to distribution.
  • The most frequent reactions reported in the Pfizer-BioNTech Phase 3 Trial (group of 8183 randomly selected individuals) were mild to moderate in intensity and generally resolved after a few days. The most common side effects were: Injection site pain (84%), Fatigue (63%), Headache (55%), Muscle pain (38%), Chills (32%), Joint pain (24%), and Fever (14%).
  • Serious adverse events were not different between the vaccine and placebo groups (0.6% versus 0.5%).
  • The vaccine has 95% efficacy in preventing COVID-19 symptoms in healthy individuals when assessed 7 days after the second dose.
  • For elderly individuals who were obese or had medical co-morbidities, the vaccine was about 92% effective.
  • Pregnant women and children were not enrolled into the study. Studies are underway for older children and possibly younger children in the future.
  • The risk of COVID-19 for those in the vaccine group started decreasing 2 weeks after the first dose. The estimated effectiveness of 1 dose is about 52% (based on very little evidence)
  • A small subset of individuals were followed to 14 weeks in the published study data, thus the duration of protection from COVID-19 is still unknown. However, the study plans to follow people for a total of 2 years after the second vaccine dose. Other things the study data cannot tells are whether the vaccine will provide herd immunity (i.e. community spread) or if boosters will be needed.
  • If the vaccine can prevent community spread, 200 million Americans would need to be vaccinated    (about 70% of the population) for herd immunity.
  • The study size was large enough (19,000 people in the vaccine and placebo group each) to detect common side effects. More rare side effects are likely to be reported as billions of people will be vaccinated. In more scientific terms: If an adverse event were truly to occur 0.01% of the time, the study would have an 83% of finding it.

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