BACKGROUND AND PURPOSE: 

• BNT162b2 is a lipid nanoparticle–formulated, nucleoside-modified RNA vaccine that encodes a prefusion stabilized, membrane-anchored SARS-CoV-2 full-length spike protein
  • The messenger RNA (mRNA) used in this vaccine includes the code used by SARS-CoV-2 to produce spike protein that helps the virus enter and infect cells
  • Following vaccination, the mRNA enters the vaccine recipient’s normal cells that will use the mRNA code to produce spike proteins that will generate an immune reaction
  • In the future, if the vaccine recipient is exposed to the SARS-CoV-2 virus, the antibodies generated by this immune system reaction will recognize and neutralize the invading virus
• Polack et al. (NEJM, 2020) report on the safety and efficacy of the BNT162b2 (Pfizer-BioNTech) vaccine in preventing COVID-19

METHODS:

• Ongoing multinational, placebo-controlled, observer-blinded, pivotal efficacy trial
• Participants
  • ≥16 years old
• Interventions
  • BNT162b2 vaccine candidate
    • 30 μg per dose
    • Two doses, 21 days apart
  • Placebo
• Study design
  • 1:1 randomization
• Primary outcome
  • Efficacy of the vaccine against laboratory-confirmed COVID-19
  • Safety

RESULTS:

• 42,448 participants were randomized and received injections
  • BNT162b2: 21,720 participants
  • Placebo: 21,728 participants
• BNT162b2 was 95% effective in preventing COVID-19
  • Placebo: 162 cases
  • BNT12b2: 8 cases (onset at least 7 days after the second dose)
  • (95% CI, 90.3 to 97.6)
• Similar vaccine efficacy (generally 90 to 100%) was observed across subgroups defined by
  • Age | Sex | Race | BMI | Coexisting conditions
• There were 10 cases of severe COVID-19 with onset after the first dose
  • Placebo: 9 cases
  • BNT162b2: 1 case
• Side effects
  • Mild-to-moderate pain at the injection site
  • Fatigue
  • Headache
• Fever (≥38°C): After second dose: 16% of younger vaccine recipients (16 to 55 years) | 11% of older recipients (>55 years)
  • Fever ≥38.9 to 40°C
    • After first dose: 0.2% of vaccine recipients | 0.1% of placebo
    • After second dose: 0.8% of vaccine recipients | 0.1% placebo
  • Fever >40.0°C
    • 2 participants each in the vaccine and placebo groups
• Incidence of serious adverse events was low and similar for the vaccine and placebo groups

CONCLUSION:

• Two doses of BNT162b2 spaced 21 days apart conferred 95% protection against COVID-19 in people aged 16 and over with a safety profile similar to other vaccines
• This study does not address the following populations
  • Adolescents | Children | Pregnant women
• Vaccine requires very cold temperatures for shipping and long-term storage
  • Standard refrigerators can be used for up to 5 days when ready for use
• The authors state

The data presented in this report have significance beyond the performance of this vaccine candidate

The results demonstrate that Covid-19 can be prevented by immunization, provide proof of concept that RNA-based vaccines are a promising new approach for protecting humans against infectious diseases, and demonstrate the speed with which an RNA-based vaccine can be developed with a sufficient investment of resources

Learn More – Primary Sources:

Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine

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