key: cord-0688649-po4940ao authors: Selby, Laura M.; Hewlett, Angela L.; Cawcutt, Kelly A.; Wood, Macy G.; Balfour, Teresa L.; Rupp, Mark E.; Starlin, Richard C. title: Effect of severe acute respiratory coronavirus virus 2 (SARS-CoV-2) mRNA vaccination in healthcare workers with high-risk coronavirus disease 2019 (COVID-19) exposure date: 2021-05-03 journal: Infection control and hospital epidemiology DOI: 10.1017/ice.2021.193 sha: f7b4384eb45e788263181ff9a02a8d3ce586fbb2 doc_id: 688649 cord_uid: po4940ao Appropriate precautions for fully vaccinated healthcare providers following high risk household SARS CoV-2 exposure remains unknown. Herein, we report initial results from our employee health protocol for such situations. in a screening program rather than completing a home quarantine period. Employees were eligible for the screening program if their exposure was >7 days after the second dose of SARS-CoV-2 vaccine and they remained asymptomatic. If these criteria were met, the employees underwent a nasopharyngeal swab (NP) for SARS-CoV-2 testing by PCR, and, if negative, they were allowed to return to work. The employee was then tested serially by NP swab every 5-7 days until at least 7 days from their last exposure to the SARS-CoV-2-positive household member during the period of viral shedding (typically 10 days). Employees were instructed to self-isolate from the positive individual in the home, if logistically feasible. Employees unable to do so were not excluded from the serial testing program, but their period of serial testing was extended until 7 days after the household contact was considered noninfectious. As of March 30, 2021, 48 employees had been enrolled in the protocol. Of these, 5 were still actively undergoing serial testing, and 43 completed the protocol. Among them, 38 did not develop symptoms and were negative for SARS-CoV-2 on entry into protocol and on serial testing. Also, 13 employees had 1 test. Furthermore, 11 were able to physically distance away from the positive contact; 23 had 2 negative tests; and 2 had 3 or more negative tests. Moreover, 5 employees tested positive: 3 employees were positive in the protocol and 2 were positive on entry testing. These data currently represent a vaccine failure rate of 11.6% (5 of 43). We were not able to determine whether physical distancing in the household had any impact on transmission. Of the 5 fully vaccinated employees who tested positive, all had asymptomatic or mild disease. None developed severe disease requiring hospitalization, which is consistent with previously published data about infections in individuals vaccinated with SARS-CoV-2 mRNA vaccines. 5, 6 However, 3 developed mild symptoms with cough, fever, congestion, or headache, and 2 were asymptomatic ( Table 1) . None of the employees who tested positive were immunocompromised. They ranged in age from 23 to 29 years. The timing of the positive result did not show a trend. Furthermore, 2 employees tested positive at initiation of the protocol: 1 was asymptomatic and 1 with mild symptoms. Of the remaining 3 employees, 2 developed symptoms and tested positive on the second test. The last employee remained asymptomatic and tested positive on the final test in the protocol. The cycle threshold (Ct) values for the asymptomatic individuals were 37 and 38, and the Ct values were 21, 26, and 30 for the symptomatic employees (Table 1) . These relatively high Ct values are consistent with reports that viral loads, as measured by Ct values, are lower >12 days after mRNA vaccination compared to nonvaccinated individuals. 7 All 5 vaccinated employees who tested positive had a domestic partner as the positive household contact. None of employees who were exposed to a positive child or nonsignificant other adult became infected. Spousal relationship has previously been shown to be a high risk for secondary infection, with a mean household secondary attack rate of spouses of 37.8% in prevaccination data. 8 In our limited sample, the rate of secondary infection in vaccinated healthcare workers when exposed to a SARS-CoV-2-positive partner was 22.7%, which represents a significant risk of infection. Although our study had a small sample size, the data demonstrate a persistent risk of acquisition of infection following exposure to a household member, particularly a partner with COVID-19. None of the vaccinated employees developed severe disease, which is encouraging but could also be due to risk profile. Further research into COVID-19 after vaccination is needed, including the likelihood of transmission by fully vaccinated, asymptomatic individuals in different settings. Note. Ct, cycle threshold. a Ct values obtained on the Roche Cobas 6800 system using the SARS-CoV-2 and influenza A&B assays. Infection and mortality of healthcare workers worldwide from COVID-19: a systematic review Epidemiology of and risk factors for coronavirus infection in health care workers: a living rapid review Personal protective equipment (PPE) and infection among healthcare workers-what is the evidence? Return to work for healthcare workers with confirmed COVID-19 infection Safety and efficacy of the BNT162b2 mRNA COVID-19 vaccine Efficacy and safety of the mRNA-1273 SARS-CoV-2 vaccine Initial report of decreased SARS-CoV-2 viral load after inoculation with the BNT162b2 vaccine Household transmission of SARS-CoV-2: a systematic review and meta-analysis Acknowledgments. We would like to acknowledge the hard work and dedication of the UNMC Infectious Diseases Division and the Employee Health, Infection Prevention and clinical laboratory teams at Nebraska Medicine along with all frontline healthcare workers for all of their efforts during this pandemic.Financial support. No financial support was provided relevant to this article.Conflicts of interest. All authors report no conflicts of interest relevant to this article.