Editor’s Note: This letter was published on August 18, 2021, at NEJM.org.


Breakthrough Infections in BNT162b2-Vaccinated Health Care Workers

To the Editor:

Characteristics of BNT162b2-Vaccinated Health Care Workers with Breakthrough Infections.

Hacisuleyman et al.1 described a cohort of 417 health care workers who had received the BNT162b2 (Pfizer–BioNTech) or mRNA-1273 (Moderna) mRNA vaccine. Two women in that cohort (0.48%) had breakthrough infections with SARS-CoV-2 variants. At our institution, 1137 health care workers were fully vaccinated with BNT162b2. Of these, 4 immunocompetent women (0.35%) had breakthrough infections; these infections occurred later than those in the study by Hacisuleyman et al. (at a median of 62 days after the second vaccine dose, as compared with 25 days) (Table 1).1,2 This failure rate is higher than that in the initial phase 3 trial, in which 0.05% of vaccinated participants (8 of 17,411) had a breakthrough infection 7 or more days after the second BNT162b2 vaccine dose,3 but is lower than in other recent studies involving health care workers.2,4,5

The health care workers at our institution had only mild symptoms but high viral loads (cycle thresholds of <25) and prolonged viral shedding up to 32 days after diagnosis. We performed a genomic characterization of the spike protein variants (delHV69/70, N501Y, A570D, D614G, and P681H), and all strains were classified as the B.1.1.7 (or alpha) variant.

Vaccinated health care workers can be infected with variants of concern transmitted from unvaccinated household contacts and may transmit SARS-CoV-2 in the hospital if not screened early enough. Finally, variants of concern may not only be more transmissible than the original SARS-CoV-2 but may also escape vaccine protection more frequently.

Bettina Lange, M.D.
Marlis Gerigk, M.D.
Tobias Tenenbaum, M.D.
University Medical Center Mannheim, Mannheim, Germany

Disclosure forms provided by the authors are available with the full text of this letter at NEJM.org.

This letter was published on August 18, 2021, at NEJM.org.

  1. 1. Hacisuleyman E, Hale C, Saito Y, et al. Vaccine breakthrough infections with SARS-CoV-2 variants. N Engl J Med 2021;384:2212-2218.

  2. 2. Keehner J, Horton LE, Pfeffer MA, et al. SARS-CoV-2 infection after vaccination in health care workers in California. N Engl J Med 2021;384:1774-1775.

  3. 3. Polack FP, Thomas SJ, Kitchin N, et al. Safety and efficacy of the BNT162b2 mRNA Covid-19 vaccine. N Engl J Med 2020;383:2603-2615.

  4. 4. Benenson S, Oster Y, Cohen MJ, Nir-Paz R. BNT162b2 mRNA Covid-19 vaccine effectiveness among health care workers. N Engl J Med 2021;384:1775-1777.

  5. 5. Hall VJ, Foulkes S, Saei A, et al. COVID-19 vaccine coverage in health-care workers in England and effectiveness of BNT162b2 mRNA vaccine against infection (SIREN): a prospective, multicentre, cohort study. Lancet 2021;397:1725-1735.

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