Background The preventive effect which tenofovir/emtricitabine could have against SARS-CoV-2 in HIV-negative people is unknown. The objective of this study was to analyse the seroprevalence and clinical manifestations of COVID-19 among users of PrEP, TDF/FTC or TAF/FTC, and to compare it to that of a control group. Methods Observational descriptive study of the seroprevalence of antibodies for SARS-CoV-2 among men who have sex with men and transgender women without use of PrEP(Group1;n=250) and PrEP users with TDF/FTC(n=409) or TAF/FTC(n=91) (Group2;n=500), conducted from 11-May-2020 to 27-Jun-2020. All were provided with a structured questionnaire which collected information on the variables to be analysed and testing for IgG antibodies to SARS-CoV-2 (CMIA) was then carried out. Results The seroprevalence of SARS-CoV-2 was 9·2%(95% CI: 5·9-13·5) in the group without PrEP and 15.0%(95% CI: 12·0-18·4) in the group with PrEP(p=0·026). Among users of TDF/FTC it was 14.7%(95% CI: 11·4-18·5) and in users of TAF/FTC it was 16·5%(95% CI: 9·5-25·7)(p=0·661). In those positive for SARS-CoV-2 receiving PrEP, 57·4% manifested symptoms compared to 78·3% in the control group (p=0·070). In users of TDF/FTC the figure was 53·3% and TAF/FTC 73·3%(p=0·100). The duration of symptoms was 11·5 days in the control group, 9·0 in PrEP users(p=0·116), 7·0 in users of TDF/FTC and 13·0 in users of TAF/FTC(p = 0·100). Conclusion Users of PrEP, TDF/FTC or TAF/FTC presented a higher seroprevalence to SARS-CoV-2 than the control group. No statistically significant differences were found in relation to clinical manifestations. PrEP users should use the same prevention measures as those indicated for the general population.

Detection of mutations by multiplex real-time RT-PCR is a widely used method for the screening of SARS-CoV-2 variants, but this method has several limitations. We describe three cases in which a Mu strain containing the mutation K417N was initially misclassified as the Beta variant. We recommend the detection of P681H to distinguish between these two variants. Our experience highlights the importance of keeping track of new variants and mutations in order to adapt the current workflows.

Despite social distancing measures implemented in Madrid to prevent the propagation of SARS-CoV-2, a significant increase (57.1%; 28.5 to 38.5 cases/month) in cases of lymphogranuloma venereum was detected during the COVID-19 pandemic. This unusual scenario might have accelerated a shift in Chlamydia trachomatis (CT) epidemiology towards a higher proportion of L genotypes compared with non-L genotypes in CT-positive samples. Our data underscore the importance of surveillance of sexually transmitted infections during the pandemic, in particular among vulnerable populations.