Janssen (J&J) COVID-19 Vaccine

by David O. Freedman, M.D. last updated 2022-01-11 08:39:03.167637-05:00 © Antimicrobial Therapy, Inc.
Janssen/Johnson & Johnson, J&J, Ad26.COV2.S



  • Janssen COVID-19 Vaccine. Ad26.COV2.S

Authorized for Use in

  • US FDA (not considered as a preferred vaccine), Health Canada, EU EMA, UK, WHO EUL, Australia TGA.  


  • >18 years


  • Non-replicating adenovirus vector

Primary Dosing

  • Persons age ≥ 18 yrs: 0.5 mL IM (5 X 1010 virions) x 1 dose including immunocompromised persons
  • Persons age 5-18 yrs: Not approved in this age group

Booster Dosing

  • 0.5 mL IM (same as dose 1) given at least 2 months after the first Janssen/J&J dose—may be give to all persons aged ≥ 18 years, including immunocompromised persons but an mRNA vaccine is preferred for this dose in previous Janssen/J&J vaccinees. If Janssen/J&J is used for dose 1 and Moderna is used for dose 2 use 50 ug dose of Moderna and if Pfizer is used for dose 2 use 30 µg
  • No additional doses recommended 5 months later as with mRNA vaccine. 
  • Three doses of mRNA vaccine is the only current effective strategy against the Omicron variant; no data yet on heterologous dosing with Janssen/J&J and subsequent mRNA boosters


  • CDC recommends that persons aged ≥ 18 years (including moderately or severely immunocompromised persons who received an additional primary dose) who were fully vaccinated with a WHO EUL vaccine not authorized/approved by US FDA or with a heterologous series composed of any FDA-authorized/approved or WHO EUL authorized vaccine are eligible to receive a single booster dose of the Pfizer vaccine (0.3 mL; 30 µg) at least 6 months after completion of their primary series under the existing age guidelines as for Moderna and Pfizer vaccines. Practically, either mRNA vaccine may be used for a booster in this situation.


  • 2-8°C (36-46°F) for up to 3 mos (for shipping and use); -20°C (-4°F) for up to 2 yrs


Overall against symptomatic disease

  • 76% (US trial); 66.9% (US, Brazil, South Africa combined)
    • Overall efficacy against symptomatic disease in Phase 3 trials was pre-delta. Specific vaccine efficacy (VE) data against beta, gamma no longer relevant.

Real world against hospitalization

  • VE by vaccine (delta era): against hospitalization Moderna 95%, Pfizer 80%, J&J 60%. Poor efficacy of Janssen/J&J in South Africa asgainst beta. Waning immunity against hospitalization for delta very significant for >65 years of age.

Age > 65 years

  • 66.10%


  • Not approved

Against severe disease / death

  • 85.4% vs severe / critical; 100% against death in Phase 3. 81% VE against beta. Real world predelta: 68% against hospitalization and 73% against an emergency department or urgent care visit.

Against asymptomatic infection / transmission

  • Delta variant results in peak viral loads 1,000 times higher than the alpha variant and is equal between vaccinated and unvaccinated persons, but virus is cleared more rapidly in vaccinated

Duration of efficacy after final dose

  • Durable humoral and cellular immune responses with minimal decreases for at least 8 months in pre-delta subjects. Few data with this vaccine. Duration against delta and omicron variants especially in
    immunocompromised and elderly is unknown and of concern.




  • Same as Pfizer BioNTech mRNA and Moderna mRNA plus persons with a contraindication to mRNA COVID-19 vaccines (including allergy to PEG) have a precaution to the Janssen/J&J vaccine (cross-reactive polysorbate 80) and vice-versa.

Not contraindications

Adverse effects

  • Among 16.9 million Janssen/J&J vaccinees in the US 57 cases (including 9 deaths) of TTS following the primary dose of the Janssen/J&J vaccine have been reported in males (17 cases) and females (37 cases) aged ≥ 18 years, with an overall rate of 0.38 cases per 100,000 doses; the highest rate (1 case per 100,000 doses administered) is among females aged 30-49 years. Similar case rates (.45 cases per 100,000 doses administered) were observed in females aged 18-29 years, females aged 50-64 years, and males aged 40-49 years.Treat with oral anticoagulants and IVIG. No heparin for any thrombotic event withing 2 weeks of vaccination without negative anti-PF4 result. N Engl J Med. 2021; 384:1964.
  • No data yet on anaphylaxis, none in trials, contains polysorbate 80 related to PEG.
  • Injection-site reactions (pain), fatigue, headache, fever, and weakness.
  • Avoid if possible if previous GBS especially males over 50. GBS approximately 8/million vaccinees compared to 1.7 baseline rate.

Special Needs Populations


  • Use. No reproductive or development concerns (preliminary); risk of disease effect > known vaccine risk; endorsed for use by ACOG. VSD data with insufficient numbers

Immunocompromised / HIV

  • Give dose 2 (0.5 mL IM; same as dose 1) at least 2 months after the first Janssen/J&J dose—is recommended for all persons aged ≥ 18 years, including immunocompromised persons.
  • Dose 2 with an mRNA vaccine following vaccination with the Janssen/J&J vaccine is an option in the US but is preferable according to most experts (30 µg if Pfizer; 50 µg if Moderna). Booster dose (dose 3) preferably with same mRNA vaccine 6 months after dose 2. Serology not indicated before or after. Janssen for doses 2 and 3 permitted after mRNA vaccine but not desirable.