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COVID-19

Durability of Humoral and Cell-Mediated Immunity Post-Pfizer Vaccination

Strategic Insights

— 1 min read

A new study evaluated the durability of humoral and cell-mediated immunity (CMI) post-Pfizer vaccination among healthcare workers at a tertiary care center in Lebanon. The study enrolled 42 healthcare workers, with their past infection and/or vaccination duration ranging between 2 months and 2 years. The researchers found that only 83.3% and 45.2% among the Pfizer-vaccinated healthcare workers tested positive for COVID humoral and CMI, respectively. The study concluded that no correlation was established between humoral and CMI responses following COVID-19 vaccination, highlighting the need for more comprehensive testing methodologies to assess post-vaccination immunity.

Key Takeaways:

  • The study enrolled 42 healthcare workers, with 69% female and 31% male, aged 22-51 years.
  • SARS-CoV-2 was contracted by 33 (78%) healthcare workers.
  • Positive COVID humoral IgG and CMI response were found among 35 (83.3%) and 19 (45.2%) healthcare workers, respectively.
  • No correlation was established between humoral and CMI responses following COVID-19 vaccination.
  • The study reveals incongruity between humoral and CMI responses post-vaccination.
  • The researchers found concordant positivity in 35.7%, concordant negativity in 7.1%, Pos IgG - Neg IGRA in 47.6%, and Neg IgG - Pos IGRA in 9.5%.
  • The study concludes that more comprehensive testing methodologies are needed to assess post-vaccination immunity.

Statistics:

  • 42 healthcare workers were enrolled in the study.
  • 69% of the healthcare workers were female, and 31% were male.
  • 33 (78%) healthcare workers contracted SARS-CoV-2.
  • 35 (83.3%) healthcare workers tested positive for COVID humoral IgG.
  • 19 (45.2%) healthcare workers tested positive for COVID CMI.
  • 35.7% of the healthcare workers had concordant positivity in both tests.
  • 7.1% had concordant negativity in both tests.
  • 47.6% had positive IgG - negative IGRA.
  • 9.5% had negative IgG - positive IGRA.

Sources:

  • NewsRx. Researchers from American University of Beirut Medical Center Publish Findings in COVID-19 (Assessing COVID IGRA and IgG antibodies in healthcare workers post vaccination). Medical Letter on the CDC & FDA. June 22, 2025; p 178.
  • Journal of Infection in Developing Countries. Assessing COVID IGRA and IgG antibodies in healthcare workers post vaccination. 2025, 19(05).
  • American University of Beirut Medical Center. Department of Pathology and Laboratory Medicine.

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