SARS-CoV-2 infections after the breakthrough of the vaccination are enriched with worrying variants

Of the 20 breakthrough SARS-CoV-2 infections detected in fully vaccinated individuals in Washington state, the United States, all were caused by Variants of Concern (VOC). These results were published in Clinical Infectious Diseases.

A SARS-CoV-2 genome sequencing program was started after February 2021. Individuals (n = 20) who were fully vaccinated with the Pfizer BioNTech COVID-19 vaccine or the Moderna COVID-19 vaccine and tested positive for SARS-CoV-2 were subjected to whole virus genome sequencing . A group of primary infection control persons served as a comparison group (n = 5174).

The patients were 13 women, 6 men and one whose gender was not recorded had an average age of 43 years (interquartile range [IQR], 28-58) years and the median cycle thresholds were 20.2 (IQR, 17.1-23.3).

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Most of the 18 people for whom clinical data were available reported symptoms (n = 15), but none had to be hospitalized.

The VOCs detected for breakthrough infections were B.1.1.7 (40%), B.1.429 (40%), B.1.427 (10%), B.1.351 (5%) and P.1 (5%). VOC were detected in 68% of the comparison sample, including 31% B.1.1.7, 27% B.1.429, 7% P.1, 3% B.1.427 and 1% B.1.351.

Compared to infections in the control group, the VOC in breakthrough infections were increased by 1.47 times (95% CI, 1.45-1.50; P = 0.001).

The distribution of the variants differed significantly between the cohorts (P = .001) in which variants that were less effectively neutralized by vaccine antibodies (B.1.351, B.1.427, B.1.429, P.1) were around 1.63 times were increased (95% CI 1.14-2.34; P = 0.037 for breakthrough infections.

The specific W258L mutation that alters the spike protein was increased 15.22-fold (95% CI, 3.91-59.10; P = 0.008) in the vaccinated cohort; however, the mutation was only detected in 2 individuals.

This study was limited by the small sample size and the fact that most breakthrough infections were found in health care workers, which may have skewed these results.

According to these results, breakthrough infections were more likely to be caused by VOC than infections in the unvaccinated population. Continuous monitoring is needed to ensure that certain VOCs can be included in new or booster formulations for SARS-CoV-2 vaccines.

Disclosure: Some authors stated links with biotech, pharmaceutical, and / or device manufacturers. For a full list of the author’s disclosures, see the original reference.


McEwen AE, Cohen S, Bryson-Cahn C, et al. Worrying variants are over-represented in groundbreaking post-vaccination SARS-CoV-2 infections in Washington state. Clin Infect Dis. Published online June 24, 2021. doi: 10.1093 / cid / ciab581

This article originally appeared on Infectious Disease Advisor

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