key: cord-0945529-gmc3qrci authors: de Miranda Santos, Isabel Kinney Ferreira; Costa, Carlos Henrique Nery title: Impact of Hydroxychloroquine on Antibody Responses to the SARS-CoV-2 Coronavirus date: 2020-08-04 journal: Front Immunol DOI: 10.3389/fimmu.2020.01739 sha: 356f2f98358b48b1e59b1b42617e7ce79f6dca8f doc_id: 945529 cord_uid: gmc3qrci nan Recent large observational studies indicate that hydroxychloroquine (HY) does not affect outcomes of patients hospitalized with COVID-19 (1, 2) and may even be harmful (3) . Results of double-blind, randomized studies to assess efficacy of HY more rigorously are still not available. In spite of these facts, officials are currently advocating use of hydroxychloroquine (HY) for treatment and even prevention of COVID-19. In view of this situation and of the importance of correct interpretation of antibody profiles for planning preventive measures for COVID-19, we would like to bring the attention of readers to studies that raise concerns about the possible impact of HY upon antibody responses to SARS-CoV-2. HY and chloroquine are lysosomotropic drugs that increase the pH of the lysosome, thus affecting functions of proteins involved in antigen presenting pathways and in B-cell activation (7) . To the best of our knowledge, there are no new facts in the scientific and medical literature that indicate that the same mechanism could not operate in HY-treated patients suffering from COVID-19 and negatively impact their SARS-CoV-2-specific antibody responses. Indeed, recent findings indicate that some individuals, including hospitalized patients, who have recovered from COVID-19 have not made vigorous IgG antibody responses. However, the most comprehensive publications addressing antibody responses, wherein study subjects presented viability in levels of IgG antibody responses, have not detailed the treatment regimens delivered to the subjects (8) (9) (10) (11) . Plans for employing immunity profiles against SARS-CoV-2 to relax social distancing and other epidemic mitigation measures and to create "immunity passports" to control spread of COVID-19 have recently been questioned by the World Health Organization because of uncertainty regarding antibody responses (12) . As more needs to be learned about the role of antibodies in recovery from and protection against infection with SARS-CoV-2, the impact of HY and other treatment regimens on antibody responses requires systematic evaluation. Observational study of hydroxychloroquine in hospitalized patients with Covid-19 Association of treatment with hydroxychloroquine or azithromycin with in-hospital mortality in patients with COVID-19 in New York State Hydroxychloroquine or chloroquine with or without a macrolide for treatment of COVID-19: a multinational registry analysis Antibody response to preexposure human diploid-cell rabies vaccine given concurrently with chloroquine Humoral immune response to tetanus-diphtheria vaccine given during extended use of chloroquine or primaquine malaria chemoprophylaxis Effect of antimalarial drugs on the immune response to intramuscular rabies vaccination using a postexposure prophylaxis regimen Mechanisms of action of hydroxychloroquine and chloroquine: implications for rheumatology Temporal profiles of viral load in posterior oropharyngeal saliva samples and serum antibody responses during infections by SARS-CoV-2: an observational cohort study Detection of SARS-CoV-2-specific humoral and cellular immunity in COVID-19 convalescent individuals Evaluation of the EUROIMMUN anti-SARS-CoV-2 ELISA assay for detection of IgA and IgG antibodies A systematic review of antibody mediated immunity to coronaviruses: antibody kinetics, correlates of protection, and association of antibody responses with severity of disease Available online at: www.who.int/newsroom/commentaries/detail/immunity-passports-in-the-context-of-covid-19 All authors listed have made a substantial, direct and intellectual contribution to the work, and approved it for publication.