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Vaccine Breakthrough Infections With SARS-CoV-2 Variants
Quick Takes
- In a group of >400 patients who received both doses of mRNA vaccine against SARS-CoV-2, two patients developed mild infection with variant strains.
- Breakthrough infection may occur despite the presence of neutralizing antibodies.
Study Questions:
Among persons who have received both doses of a mRNA-based vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), what is the risk of breakthrough infection?
Methods:
In this single-center study, 417 university employees who had received a second dose of a mRNA-based vaccine (Pfizer or Moderna) ≥2 weeks previously were followed with weekly saliva antigen testing. For patients with breakthrough infection, genetic sequencing was performed.
Results:
Two patients developed breakthrough infection, with symptoms including sore throat, headache, fever, fatigue, sinus congestion, and anosmia. Symptoms lasted 5 days in one patient and 7 days in the other. Neither required hospitalization. In both patients, viral genome sequencing revealed mutations in the spike (S) gene of potential clinical concern. In patient 1, mutations included E484K, which confers resistance to some types of neutralizing antibodies. Patient 1 had high serum levels of neutralizing antibodies. The variant strain found in patient 1 was found to be related to but distinct from the UK variant B.1.1.7 and the New York City variant B.1.526. Neutralization assays with a serum sample from patient 1 showed similar efficacy against wild-type virus, the B.1.526 mutant, and the E484K mutant.
Conclusions:
In a group of >400 patients who received both doses of mRNA vaccine against SARS-CoV-2, two patients developed mild infection with variant strains. Breakthrough infection may occur despite the presence of neutralizing antibodies.
Perspective:
These findings re-emphasize the critical role of vaccination in preventing severe disease. Ongoing work to develop new vaccines and boosters that provide increased protection against variants will be important in the long term. Meanwhile, public health measures including masking remain essential to limiting outbreaks.
Clinical Topics: Cardiovascular Care Team, COVID-19 Hub, Prevention
Keywords: Antibodies, Neutralizing, Coronavirus, COVID-19, Disease Outbreaks, Fatigue, Fever, Genome, Viral, Headache, Immunization, Secondary, Mutation, Pharyngitis, Primary Prevention, Public Health, RNA, Messenger, SARS-CoV-2, Vaccination, Vaccines
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