Pfizer’s vaccine is showing efficacy greater than 90%, and an emergency use authorization (EUA) was granted by the FDA on December 11. The FDA Briefing Document is available for review here.

A preliminary, non peer-reviewed article shows sera from patients who completed both doses of the Pfizer BioNTech vaccine had similar neutralizing geometric mean titers (GMTs) against SARS-CoV-2 engineered to contain the same mutations as the UK and South African variants, compared to the wild-type, although the GMTs against the South African variant were 19% lower. The authors note that the engineered viruses do not contain the full set of mutations present in the UK and South African variants.


Moderna’s vaccine is showing a 95% efficacy rate and the vaccine can safely be stored at -25 degrees Fahrenheit. (December 31, 2020) Their EUA application was approved on December 18. The FDA briefing document is available for review here.

Janssen COVID-19 Vaccine
  • Preliminary data from the Phase 3 ENSEMBLE vaccine trial was released on January 29. Among all participants from different geographies and including those infected with an emerging viral variant, Janssen’s COVID-19 single shot vaccine candidate was 66% effective overall in preventing moderate to severe COVID-19, 28 days after vaccination.
    • The onset of protection was observed as early as day 14. The level of protection against moderate to severe COVID-19 infection was 72% in the United States, 66% in Latin America and 57% in South Africa, 28 days post-vaccination.
    • The vaccine candidate was 85% effective in preventing severe disease across all regions studied, 28 days after vaccination in all adults 18 years and older.
    • The vaccine candidate demonstrated complete protection against COVID-related hospitalization and death, 28 days post-vaccination.
  • The EUA was approved on February 27 and the vaccine fact sheet is available here. The FDA briefing document is available here.
  • Interim results from the phase 1-2a trial of the Johnson & Johnson vaccine were reported in the NEJM on January 13. This vaccine is a recombinant, replication-incompetent adenovirus 26 vector encoding a full length and stabilized SARS-CoV-2 spike protein. Results from two of three cohorts (18 to 55-year-olds and >/=65-year-olds) were reported. This trial examined the effects of single versus double dose, and low dose versus high dose.
  • Neutralizing antibody titers were detected in 90% or more of all participants on day 29 after the first vaccine dose and reached 100% by day 57 in 18 to 55-year-olds with a further increase in titers, regardless of vaccine dose or age group. Titers remained stable until at least day 71 in the 18 to 55-year olds, the latest time period in this study. A second dose provided an increase in titer by a factor of 2.6-2.9. Spike antibody titers were similar. On day 14, CD4+ T-cell responses were detected in 76 to 83% of the younger cohort, and 60 to 67% of the older cohort. CD8+ T cell responses followed a similar pattern.
  • Adverse reactions were similar to current vaccines, and occurred in 65 to 85% of recipients. The most common were fatigue, headache and myalgia.

    The UK authorized use of the AstraZeneca vaccine on December 30. 

    AstraZeneca announced that its vaccine is showing a 70% efficacy rate on average, with some groups seeing up to 90% efficacy; further study is expected. (November 23, 2020). 


    In preliminary results for Phase 2/3 trials, this adjuvated protein subunit vaccine showed up to 89.3% efficacy in the UK cohort and 85.6% efficacy against the UK variant, but results from the South African cohort showed an efficacy of 60% in the HIV-negative population where 93% had the South African variant.

      Additional Vaccine Information
      • British researchers have reported new data on the transmissibility of the new SARS-CoV-2 variant found in the UK and US. CDC officials have noted that the new variant appears unlikely to impact the effectiveness of the COVID-19 vaccine. The CDC is compiling information about the variants here.
      • In this excellent opinion article on vaccines and variants, the authors point out several issues related to this problem, including issues with suboptimal immunity limiting the number or increasing the interval between doses, ability of vaccine-induced neutralizing antibodies to attack the virus, the loss of effectiveness of monoclonal antibodies against the variants, and then they propose an approach to the problem. (JAMA, January 28)
      • This recent article from the Lancet explains why multiple vaccines may be needed across different populations. (November 14, 2020)
      • ACIP and ACOG recommend that vaccination should not be withheld from pregnant or lactating women, but they should be informed there are insufficient safety data available at this time. AAAAI research partner MotherToBaby has more information on the vaccine in pregnant and lactating women.