Background:
Distribution of mRNA-based SARS-CoV-2 vaccines to healthcare personnel (HCP) in the United States began in December 2020, with efficacy > 90%. However, breakthrough infections in fully vaccinated individuals have been reported. Meanwhile, multiple SARS-CoV-2 variants of concern have emerged worldwide, including the B.1.427/B.1.429 variant first described in California. Little is known about the real-world effectiveness of the mRNA-based SARS-CoV-2 vaccines against novel variants including B.1.427/B.1.429.
Methods:
In this quality improvement project, post-vaccine SARS-CoV-2 cases (PVSCs) were defined as individuals with positive SARS-CoV-2 PCR test after receiving at least one dose of a SARS-CoV-2 vaccine. Chart extraction of demographic and clinical information was performed, and available specimens meeting cycle threshold value criteria were tested for L452R, N501Y and E484K mutations by RT-PCR.
Results:
From December 2020 to March 2021, 184 PVSCs were identified out of 22,729 healthcare personnel who received at least one dose of an mRNA-based SARS-CoV-2 vaccine. Of these, 114 (62.0%) occurred within 14 days of first vaccine dose (early post-vaccination), 49 (26.6%) within 14 days of the second vaccine dose (partially vaccinated), and 21 (11.4%) >14 days after the second dose (fully vaccinated). Of 112 samples available for mutation testing, 40 were positive for L452R alone, presumptive of B.1.427/B.1.429; two had N501Y mutation alone and none were found with E484K mutation. Though on univariate analysis partially- and fully-vaccinated PVSCs were more likely than early post-vaccination PVSCs to be infected with presumptive B.1.427/B.1.429, when adjusted for community prevalence of B.1.427/B.1.429 at the time of infection, partially- and fully-vaccinated PVSC did not have statistically significantly elevated risk ratios for infection with this variant (RR 1.39, 95% CI 0.80-2.40 and RR 0.96, 95% CI 0.47-1.95, respectively).
Conclusions:
Of 184 PVSCs, as expected, the great majority occurred prior to the expected onset of full, vaccine-derived immunity. Although presumptive B.1.427/B.1.429 did not represent a significantly higher proportion of late PVSCs than would be expected based on rising community prevalence over the study period, numbers of PVSCs were small. Continued infection control measures in the workplace and in the community including social distancing and masking, particularly in the early days post-vaccination, as well as continued variant surveillance in PVSCs, is imperative in order to anticipate and control future surges of infection.
Depression Screening and Measurement-Based Care in Primary Care