alafenamide or tenofovir disoproxil fumarate; hydroxychloroquine; ivermectin; and supplements such as zinc, vitamin C, and vitamin D. Please check ClinicalTrials.gov for the latest information. Hydroxychloroquine, given at different doses and durations, has been studied in randomized controlled trials to assess whether it could prevent SARS-CoV-2 infection in those at risk of being exposed to infected individuals, such as health care workers. One study reported no evidence of a benefit of hydroxychloroquine, and it was ultimately halted due to futility before it reached its target enrollment.26 In another hydroxychloroquine study, which also did not meet its target enrollment and was stopped early, the majority of the potential transmission events were not confirmed by virologic testing.27 Neither study demonstrated any evidence of a reduction in the rate of acquiring infection. Both studies reported an increased frequency of mild adverse events in the treatment group. Post-Exposure Prophylaxis Anti-SARS-CoV-2 Monoclonal Antibodies • The Panel recommends against the use of bamlanivimab plus etesevimab and casirivimab plus imdevimab for post-exposure prophylaxis (PEP), as the Omicron variant and its subvariants, which are not susceptible to these agents, are currently the dominant SARS-CoV-2 variants circulating in the United States (AIII). Vaccination remains a highly effective way to prevent SARS-CoV-2 infection. However, despite the widespread availability of COVID-19 vaccines, some individuals are not fully vaccinated or cannot mount an adequate response to the vaccine. Some of these individuals, if infected, are at high risk of progressing to serious COVID-19. Bamlanivimab plus etesevimab and casirivimab plus imdevimab have previously received FDA EUAs for PEP; however, the Omicron variant and its subvariants are currently the dominant SARS-CoV-2 variants circulating in the United States. The Panel recommends against the use of these Downloaded from https://www.covid19treatmentguidelines.nih.gov/ on 7/6/2022 COVID-19 Treatment Guidelines 29 anti-SARS-CoV-2 mAbs because the Omicron variant and its subvariants are not susceptible to them (AIII). Chloroquine and Hydroxychloroquine • The Panel recommends against the use of hydroxychloroquine for SARS-CoV-2 PEP (AI). Both chloroquine and hydroxychloroquine have in vitro activity against SARS-CoV and SARS-CoV2.28,29 A small cohort study without a control group suggested that hydroxychloroquine might reduce the risk of SARS-CoV-2 transmission to close contacts.30 There have been several large trials to determine whether hydroxychloroquine can reduce the risk of infection after exposure to individuals infected with SARS-CoV-2. These studies used different dose schedules and targeted different at-risk populations. In addition, some studies were unable to confirm infection using molecular or antigen tests. None of these studies demonstrated any evidence of efficacy for hydroxychloroquine, and all showed a higher risk of generally mild adverse events in those who received the drug.31-33 Other Drugs for Post-Exposure Prophylaxis • The Panel recommends against the use of other drugs for SARS-CoV-2 PEP, except in a clinical trial (AIII). A number of other agents (e.g., ivermectin, hyperimmune gamma globulin, convalescent plasma, interferons, tenofovir with or without emtricitabine, vitamin D) are currently being investigated for SARS-CoV-2 PEP. The latest clinical trials for SARS-CoV-2 PEP can be found at ClinicalTrials.gov. High concentrations of ivermectin have been shown to inhibit SARS-CoV-2 replication in vitro.34,35 Population data indicated that countrywide, mass-use of prophylactic chemotherapy for parasitic infections, including the use of ivermectin, was associated with a lower incidence of COVID-19.36 At this time, few clinical trials have evaluated the safety and efficacy of using ivermectin for SARS-CoV-2 PrEP or PEP. Although several studies have reported potentially promising results, the findings are limited by the design of the studies, their small sample sizes, and the lack of details regarding the safety and efficacy of ivermectin. In a descriptive, uncontrolled, interventional study of 33 contacts of patients with laboratory-confirmed SARS-CoV-2 infection, no cases of SARS-CoV-2 infection were identified within 21 days of initiating ivermectin for PEP.37 In a small case-control study in SARS-CoV-2-exposed health care workers, 186 participants who became infected were matched with 186 uninfected controls. Of those who received ivermectin after exposure to SARS-CoV-2, 38 were in the infected group and 77 were in the uninfected group, which led the investigators to conclude that ivermectin reduced the incidence of SARS-CoV-2 infection.38 Clinical Spectrum of SARS-CoV-2 Infection Last Updated: October 19, 2021 Patients with SARS-CoV-2 infection can experience a range of clinical manifestations, from no symptoms to critical illness. In general, adults with SARS-CoV-2 infection can be grouped into the following severity of illness categories; however, the criteria for each category may overlap or vary across clinical guidelines and clinical trials, and a patient’s clinical status may change over time. • Asymptomatic or Presymptomatic Infection: Individuals who test positive for SARS-CoV-2 using a virologic test