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Objectives The aim of this study was to estimate how well the excess mortality reflected the burden of coronavirus disease 2019 (COVID-19)-related deaths during the March–May 2020 COVID-19 outbreak in Stockholm, Sweden, and whether the excess mortality during the outbreak might have resulted in a compensatory reduced mortality after the outbreak. Methods Using previous 10-year or 5-year average mortality rates as a baseline, the excess mortality estimates before, during, and after the COVID-19 outbreak in March–May 2020 in Stockholm were compared. Results Weekly death estimates revealed that the immediate pre-outbreak and post-outbreak all-cause mortality did not exceed to excess mortality regardless of whether previous 10-year or 5-year average mortality was used. Forty-three days after the start of the outbreak, 74.4% of the total excess mortality was reportedly explained by known COVID-19-related deaths, and the present study reports an update, showing that 15 weeks after the start of the outbreak, the reported COVID-19-related deaths explained >99% of the total excess mortality. Conclusions An exceptional outbreak feature of rapid excess mortality was observed. However, no excess but similarly low mortality was observed immediately prior to the outbreak and post-outbreak, thus emphasizing the severity of the first wave of the COVID-19 outbreak in Stockholm.

Most Covid-related infections and deaths occur in healthcare outside hospitals. We wished to explore SARS-CoV-2 infections among healthcare workers (HCWs) in this setting. All healthcare providers in Stockholm, Sweden were asked to invite HCWs at work for a study of past or present SARS-CoV-2 infections among HCWs. This study reports the results from 839 HCWs, mostly employees of primary care centers, sampled in June 2020. Prior infection, as measured using seropositivity, was found among 12% (100/839) of HCWs, ranging from 0–29% between care units. There was a significant trend of decreasing serology positivity by age (one sided p-trend 0.0467). Seropositivity was highest among HCWs

Total excess mortality peaked during a coronavirus disease 2019 (COVID-19) outbreak in Stockholm, but 25% of these deaths were not recognized as COVID-19 related nor occurred in hospitals. Estimate of total excess mortality may give a more comprehensive picture of the total disease burden during a COVID-19 outbreak, and may facilitate managing future outbreaks.

Background Whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positivity among asymptomatic subjects reflects past or future disease may be difficult to ascertain. Methods We tested 9449 employees at Karolinska University Hospital, Stockholm, Sweden for SARS-CoV-2 RNA and antibodies, linked the results to sick leave records, and determined associations with past or future sick leave using multinomial logistic regression. Results Subjects with high amounts of SARS-CoV-2 virus, indicated by polymerase chain reaction (PCR) cycle threshold (Ct) value, had the highest risk for sick leave in the 2 weeks after testing (odds ratio [OR], 11.97; 95% confidence interval [CI], 6.29–22.80) whereas subjects with low amounts of virus had the highest risk for sick leave in the 3 weeks before testing (OR, 6.31; 95% CI, 4.38–9.08). Only 2.5% of employees were SARS-CoV-2 positive while 10.5% were positive by serology and 1.2% were positive in both tests. Serology-positive subjects were not at excess risk for future sick leave (OR, 1.06; 95% CI, .71–1.57). Conclusions High amounts of SARS-CoV-2 virus, as determined using PCR Ct values, was associated with development of sickness in the next few weeks. Results support the concept that PCR Ct may be informative when testing for SARS-CoV-2. Clinical Trials Registration. NCT04411576.

Objectives Most COVID-19 related infections and deaths may occur in healthcare outside hospitals. Here we explored SARS-CoV-2 infections among healthcare workers (HCWs) in this setting. Design All healthcare providers in Stockholm, Sweden were asked to recruit HCWs at work for a study of past or present SARS-CoV-2 infections among HCWs. Study participants This study reports the results from 839 HCWs, mostly employees of primary care centers, sampled in June 2020. Results SARS-CoV-2 seropositivity was found among 12% (100/839) of HCWs, ranging from 0% to 29% between care units. Seropositivity decreased by age and was highest among HCWs Conclusions Previous SARS-CoV-2 infections were common among younger HCWs in this setting. Pre-symptomatic infection was uncommon, in line with the strong variability in SARS-CoV-2 exposure between units. Prioritizing infection prevention and control including sufficient and adequate personal protective equipment, and vaccination for all HCWs are important to prevent nosocomial infections and infections as occupational injuries during an ongoing pandemic.

Background Cervical cancer elimination through human papillomavirus (HPV) vaccination programs requires the attainment of herd effect. Due to its uniquely high basic reproduction number, the vaccination coverage required to achieve herd effect against HPV type 16 exceeds what is attainable in most populations. We have compared how gender-neutral and girls-only vaccination strategies create herd effect against HPV16 under moderate vaccination coverage achieved in a population-based, community-randomized trial. Methods and findings In 2007–2010, the 1992–1995 birth cohorts of 33 Finnish communities were randomized to receive gender-neutral HPV vaccination (Arm A), girls-only HPV vaccination (Arm B), or no HPV vaccination (Arm C) (11 communities per trial arm). HPV16/18/31/33/35/45 seroprevalence differences between the pre-vaccination era (2005–2010) and post-vaccination era (2011–2016) were compared between all 8,022 unvaccinated women, Author summary Why was this study done? High-risk human papillomavirus (HPV) infection is a necessary cause of cervical cancer in females. HPV vaccination targeting high-risk HPV types 16 and 18 has been implemented internationally. Achieving herd protection for HPV16 may require greater than 80% girls-only vaccination coverage, a level that has not been achievable in many countries. We evaluate whether gender-neutral or girls-only HPV vaccination results in HPV16 and HPV18 herd protection when the vaccination coverage is only moderate (40%–50%). What did the researchers do and find? We implemented a community-randomized trial of gender-neutral versus girls-only versus no HPV vaccination of young adolescents in 2007–2010, with 11 communities in each arm. Vaccination coverage was implemented with moderate coverage (40%–50%) at the community level. We evaluated the herd effect created by the different vaccination strategies by measuring the cumulative incidence of vaccine-protected HPV types in 8,022 young unvaccinated pregnant females (under 23 years old), comparing the time periods 2005–2010 (pre-vaccination) and 2011–2016 (post-vaccination). An HPV16 herd effect, that is, a reduction in cumulative incidence among the unvaccinated females, was only observed in communities where gender-neutral vaccination had been implemented. What do these findings mean? Achieving a vaccination coverage of above 80%, which is required to achieve herd effect against HPV16, may be unrealistic in some populations. Implementing gender-neutral HPV vaccination provides a solution to this problem as the vaccination coverage threshold required to provide herd effect to unvaccinated females is lower. Our study finds that gender-neutral vaccination provides stronger herd effect than girls-only vaccination in the setting of moderate vaccination coverage. However, these findings are limited to this setting and are not readily generalizable to settings with high (>80%) vaccination coverage.

BackgroundPre-symptomatic subjects are spreaders of SARS-CoV-2 infection, and strategies that could identify these subjects, particularly in hospital settings, are needed.MethodsWe tested a cohort of 9449 employees at work at the Karolinska University Hospital, Stockholm, Sweden for SARS-CoV-2 RNA and antibodies, linked the screening results to sick leave records and examined the association between screening results and past or future sick leave using multinomial logistic regression.ResultsWe found that healthcare workers with high amounts of SARS-CoV-2 virus, as indicated by the Cycle threshold (Ct) value in the PCR, had the highest risk for sick leave in the two weeks after testing (OR 11·97 (CI 95% 6·29-22·80)) whereas subjects with low amounts of virus had the highest risk for sick leave in the past three weeks before testing (OR 6·31 (4·38-9·08)). Only 2·5% of employees were SARS-CoV-2 positive while 10·5% were positive by serology and 1·2% were positive in both tests. Serology-positive subjects were not at excess risk for future sick leave (OR 1·06 (95% CI, 0·71-1·57)), but virus-positive subjects had a 7·23 fold (95% CI, 4·52-11·57)) increased risk for sick leave within two weeks post testing.ConclusionsScreening of asymptomatic healthcare workers for high amounts of SARS-CoV-2 virus using Ct values will identify pre-symptomatic subjects who will develop disease in the next few weeks. Identification of potentially contagious, pre-symptomatic subjects is likely critical for protecting patients and healthcare workers.Main pointHealthy healthcare workers with low amounts of SARS-CoV-2 nucleic acids will previously have had the disease. Presence of a high amount of SARS-CoV-2 nucleic acids predicts future symptomatic disease.

We compared the total excess mortality per week in relation to the reported Covid-19 related deaths in the Stockholm region (Sweden). Total excess mortality peaked under the weeks of high COVID-19-related mortality, but 25% of these deaths were not recognized as Covid-related. Most of these deaths occurred outside hospitals. Total all-cause mortality in excess to average all-cause mortality during the epidemic peak period may provide a comprehensive picture of the total burden of COVID19-related deaths.

BackgroundTransfusion of convalescent immune plasma (CP) is commonly used in epidemics. Several articles now describe clinical report data of CP for treatment of SARS-CoV-2-induced COVID-19 disease.MethodsA systematic literature review was conducted using the NCBI curated COVID-19 related open-resource literature database LitCovid to identify studies using CP as treatment for COVID-19 patients. We retrieved and curated all COVID-19 related patient and treatment characteristics from previously reported studies. A Poisson model was developed to evaluate the association between age of the patients, older age being the most common risk factor for COVID-19 mortality, and recovery time since CP treatment using data extracted from the literature.ResultsFrom 18,293 identified COVID-19 related articles, we included ten studies reporting results of CP treatment for COVID-19 from a total of 61 patients. Decreased symptoms of severe COVID-19 and clearance of SARS-CoV-2 RNA were the most direct observations. We found that patients over the age of sixty who received CP treatment for COVID-19 had a significantly prolonged recovery estimated by viral clearance (from 10 to 29 days since first dose of CP) compared to younger patients, who recovered from the infection in less than a week after receiving CP treatment.ConclusionsLimited published results on plasma transfusion treatment for COVID-19 disease with concomitant treatments suggest that CP therapy for COVID-19 is well tolerated and effective. First randomized clinical trial results, however, revealed no improvements in recovery time for elderly patients with severe COVID-19 between standard treatment alone and added with convalescent plasma. Accordingly, we argue that older patients may need a significantly longer time for recovery. Further randomized clinical trial data for COVID-19 with rigorous ethical standards is urgently needed.

Large scale human papillomavirus (HPV) vaccination against the most oncogenic high-risk human papillomavirus (HPV) types 16/18 is rapidly reducing their incidence. However, attempts at assessing if this leads to an increase of nonvaccine targeted HPV types have been hampered by several limitations, such as the inability to differentiate secular trends. We performed a population-based serological survey of unvaccinated young women over 12 years. The women were under 23-years-old, residents from 33 communities which participated in a community-randomised trial (CRT) with approximately 50% vaccination coverage. Serum samples were retrieved pre-CRT and post-CRT implementation. Seropositivity to 17 HPV types was assessed. HPV seroprevalence ratios (PR) comparing the postvaccination to prevaccination era were estimated by trial arm. This was also assessed among the sexual risk-taking core group, where type replacement may occur more rapidly. In total, 8022 serum samples from the population-based Finnish Maternity Cohort were retrieved. HPV types 16/18 showed decreased seroprevalence among the unvaccinated in communities only after gender-neutral vaccination (PR16/18A = 0.8, 95% CI 0.7-0.9). HPV6/11 and HPV73 were decreased after gender-neutral vaccination (PR6/11A = 0.8, 95% CI 0.7-0.9, PR73A = 0.7, 95% CI 0.6-0.9, respectively) and girls-only vaccination (PR6/11B = 0.8, 95% CI 0.7-0.9, PR73B = 0.9, 95% CI 0.8-1.0). HPV68 alone was increased but only after girls-only vaccination (PR68B = 1.3, 95% CI 1.0-1.7, PRcore68B = 2.8, 95% CI 1.2-6.3). A large-scale, long-term follow-up found no type replacement in the communities with the strongest reduction of vaccine HPV types. Limited evidence for an increase in HPV68 was restricted to girls-only vaccinated communities and may have been due to secular trends (ClinicalTrials.gov number: NCT00534638).

Efficacy of human papillomavirus (HPV) vaccines promises to control HPV infections. However, HPV vaccination programs may lay bare an ecological niche for non-vaccine HPV types. We evaluated type-replacement by HPV type and vaccination strategy in a community-randomized trial executed in HPV vaccination naive population. Thirty-three communities were randomized to gender-neutral vaccination with AS04-adjuvanted HPV16/18 vaccine (Arm A), HPV vaccination of girls and hepatitis B-virus (HBV) vaccination of boys (Arm B) and gender-neutral HBV vaccination (Arm C). Resident 1992-95 born boys (40,852) and girls (39,420) were invited. 11,662 boys and 20,513 girls were vaccinated with 20–30% and 45–48% coverage, respectively. HPV typing of 11,396 cervicovaginal samples was performed by high throughput PCR. Prevalence ratios (PR) between arms and ranked order of HPV types and odds ratio (OR) for having multiple HPV types in HPV16 or 18/45 positive individuals were calculated. The ranked order of HPV types did not significantly differ between arms or birth cohorts. For the non-HPV vaccinated 1992–1993 birth cohorts increased PR, between the gender-neutral intervention versus control arms for HPV39 (PRA 1.84, 95% CI 1.12–3.02) and HPV51 (PRA 1.56, 95% CI 1.11–2.19) were observed. In the gender-neutral arm, increased clustering between HPV39 and the vaccine-covered HPV types 16 or 18/45 (ORA16 = 5.1, ORA18/45 = 11.4) was observed in the non-HPV vaccinated 1994–1995 birth cohorts. Comparable clustering was seen between HPV51 and HPV16 or HPV18/45 (ORB16 = 4.7, ORB18/45 = 4.3), in the girls-only arm. In conclusion, definitively consistent postvaccination patterns of HPV type-replacement were not observed. Future occurrence of HPV39 and HPV51 warrant investigation.

Healthcare workers (HCWs) are a risk group for SARS-CoV-2 infection, but which healthcare work that conveys risk and to what extent such risk can be prevented is not clear. Starting on April 24th, 2020, all employees at work (n=15,300) at the Karolinska University Hospital, Stockholm, Sweden were invited and 92% consented to participate in a SARS-CoV-2 cohort study. Complete SARS-CoV-2 serology was available for n=12,928 employees and seroprevalences were analyzed by age, sex, profession, patient contact, and hospital department. Relative risks were estimated to examine the association between type of hospital department as a proxy for different working environment exposure and risk for seropositivity, adjusting for age, sex, sampling week, and profession. Wards that were primarily responsible for COVID-19 patients were at increased risk (adjusted OR 1.95 (95% CI 1.65-2.32) with the notable exception of the infectious diseases and intensive care units (adjusted OR 0.86 (95% CI 0.66-1.13)), that were not at increased risk despite being highly exposed. Several units with similar types of work varied greatly in seroprevalences. Among the professions examined, nurse assistants had the highest risk (adjusted OR 1.62 (95% CI 1.38-1.90)). Although healthcare workers, in particular nurse assistants, who attend to COVID-19 patients are a risk group for SARS-CoV-2 infection, several units caring for COVID-19 patients had no excess risk. Large variations in seroprevalences among similar units suggest that healthcare work-related risk of SARS-CoV-2 infection may be preventable.

Oncogenic non-vaccine human papillomavirus (HPV) types may conceivably fill the vacated ecological niche of the vaccine types. The likelihood of this may differ by the risk of acquiring HPV infections. We examined occurrence of HPV types among vaccinated and unvaccinated subgroups of 1992-1994 birth cohorts with differing acquisition risks up to 9 years post-implementation of HPV vaccination in 33 Finnish communities randomized to: Arm A (gender-neutral HPV16/18 vaccination), Arm B (girls-only HPV16/18 vaccination and hepatitis B-virus (HBV) vaccination of boys), and Arm C (gender-neutral HBV vaccination). Out of 1992-1994 born resident boys (31,117) and girls (30,139), 8,618 boys and 15,615 girls were vaccinated, respectively, with 20-30% and 50% coverage in 2007-2009. In 2010-2013, 8,868 HPV16/18 and non-HPV vaccinated females, and in 2014-2016, 5,574 originally or later (2010-2013) HPV16/18 vaccinated females attended two cervical sampling visits, aged 18.5 and 22-years. The samples were typed for HPV6/11/16/18/31/33/35/39/45/51/52/56/58/59/66/68 using PCR followed by MALDI-TOF MS. HPV prevalence ratios (PR) between Arms A/B vs. C were calculated for Chlamydia trachomatis positives (core-group), and negatives (general population minus core group). At both visits the vaccine-protected HPV type PRs did not significantly differ between the core-group and non-core group. Among the vaccinated 18-year-olds, HPV51 occurrence was overall somewhat increased (PRcore = 1.4, PRnon-core. = 1.4) whereas the HPV52 occurrence was increased in the core-group only (PRcore = 2.5, PRnon-core = 0.8). Among the non-HPV vaccinated 18-year-olds, the HPV51/52 PRs were higher in the core-group (PRcore = 3.8/1.8, PRnon-core = 1.2/1.1). The 22-year-olds yielded no corresponding observations. Monitoring of the sexual risk-taking core-group may detect early tendencies for HPV type replacement.

Background: Very high coverage human papillomavirus (HPV) vaccination of girls has the potential to eradicate some HPV types but low coverage vaccination does not. The protection of unvaccinated individuals by herd effect (HE) varies by HPV type and vaccination strategy. By combining community-randomized trial data and mathematical modeling we show that gender-neutral vaccination is superior for achieving eradication of oncogenic HPVs. Methods: We randomized 33 communities into gender-neutral HPV16/18 vaccination (A), HPV16/18 vaccination of girls only (B), and hepatitis B-virus vaccination of boys and girls (C). From 2007-2010 11,622/40,852 resident boys and 20,513/39,420 resident girls born 1992-1995 consented to the study. At follow-up in 2010-14, cervicovaginal samples from vaccinated and unvaccinated girls were typed for HPV6/11/16/18/31/33/35/39/45/51/52/56/58/59/66/68. Trial-based vaccine efficacy (VE) and HE, estimated among non-HPV vaccinated arm A/B girls using arm C controls, were weighted for mean protective effectiveness (PE) estimation, and used for modeling eradication. Findings The HPV18/31/33 HE and PE were significant in younger birth cohorts: four years post vaccination HE and PE were 150% and 40% stronger in the gender-neutral than in the girls-only arm. HPV18/31/33 have moderate to fast clearance rates enabling eradication, and corresponding HEs from vaccinated to unvaccinated arose rapidly. HPV18/31/33 eradication in adolescents/young adults is predicted in 20 years with 75% coverage of gender-neutral vaccination, eradication of HPV16 is predicted within 30 years. Interpretation While low coverage with a girls-only vaccination strategy leaves most females unprotected, HPV-disease eradication of oncogenic HPVs is certain with moderate coverage gender-neutral vaccination strategy. Funding: This ancillary study was partially funded by Academy of Finland, Finnish Cancer Organizations and EU FP7 networks PREHDICT and CoheaHR. GlaxoSmithKline Biologicals SA funded the primary study HPV-040 (NCT00534638, data to be published in a separate manuscript) but was not involved in the conduct of this ancillary study. GlaxoSmithKline Biologicals SA was provided the opportunity to review this manuscript for accuracy of primary HPV-040 data but the authors are solely responsible for final content and interpretation. V.N.P. was supported by a personal grant from the Ministry of Health, Government of Catalonia (PERIS SLT002/16/00496). Declaration of Interest: D.A., J.D., G.G., M.L. and J.P. have received grants from Merck & Co. Inc. or the GSK group of companies through their employers [Family Federation Finland (DA), Karolinska Institute (J.D., M.L.), Universities of Tampere (M.L.) or Helsinki (J.P.) or Imperial College London (G.G.)] for HPV vaccination studies. G.D. is currently a full time employee of Takeda Vaccines, but was working for GSK Biologicals at the time the study was planned and conducted. He holds several patents in the HPV field which have been assigned to the GSK groups of companies and has stock shares in both the GSK groups of companies and Takeda. Ethical Approval: The HPV-040 study (Eudra-CT-2007-001731-55, NCT00534638), and parallel ancillary studies on Chlamydia trachomatis screening (Dnro 111/2009) and HPV screening (ETL-code 13149, NCT02149030) were approved by Finnish ethical committees of the Pirkanmaa and PohjoisPohjanmaa hospital districts in 2007, 2009 and 2013, respectively.

Background: Human papillomavirus (HPV) basic reproductive numbers are low, except for HPV type 16. Thus, vaccination can induce herd effects to reduce the prevalence of many HPV types, especially if gender-neutral vaccination strategy and a vaccine with broad protection against HPV types are used. Methods: We used a cluster-randomized trial implemented in 2007-2009 among early, 1992-1995 born adolescents to create differential herd effects in 11 communities with gender-neutral (Arm A), and 11 communities with girls-only (Arm B) HPV16/18 vaccination achieving 20% coverage in Arm A boys and 45% coverage in Arm A and Arm B girls. In 11 control communities, devoid of any opportunistic HPV vaccination, hepatitis B-virus vaccination covered 30% of boys and 50% of girls. Seroprevalence was assessed for 17 HPV types in consecutive calendar-time (2005-07, 2008-10, 2011-13, 2014-16) strata comprising unvaccinated adolescent and young adult females, who were respectively 19 years or younger, and 20 to 22 years of age at the time of serum sampling. Sexual risk-taking behaviour core-group was defined by herpes simplex virus type-2 antibody positivity. From observed data probabilistic networks and simulated equal size seroprevalence datasets (N=100,000) were also derived. Findings: Following gender-neutral vaccination significant HPV16/18 herd effects were rapidly detected in the adolescent core-group of the gender-neutral vaccination Arm A. HPV51 prevalence tended to increase later in the post-vaccination era (2014-16) among adolescent core-group girls-only vaccination Arm B, as also supported by the simulations. Interpretation: Low to moderate coverage HPV vaccination induces a strong herd effect against HPV16/18 infection reducing circulation of vaccine-targeted HPV types following gender-neutral vaccination. The ecological niche vacated is not immediately filled. Funding Statement: This study was partially funded by Academy of Finland, Finnish Cancer Organizations and EU FP7 networks PREHDICT and CoheaHR. GlaxoSmithKline Biologicals SA funded the community randomized HPV-040 trial (NCT00534638), (data to be published in a separate manuscript) however was not in any way involved in the conduct of this study. This study received some support via a personal grant from the Ministry of Health, Government of Catalonia (PERIS SLT002/16/00496).The study was supported by grants from the Swedish Cancer Society (CAN 2015/399 and CAN 2017/459), from the Swedish Foundation for Strategic Research (grant number RB13-0011) and from Karolinska Institutet (Dnr. 2018-01523). ML received funding from KI to his Professorship (Dnr. 2-3698/2017). Declaration of Interests: JD and ML have received grants from Merck & Co. Inc and the GSK group of companies through their employers the Karolinska Institute (both JD and ML), or the University of Tampere (ML) for conducting HPV vaccination studies. Ethics Approval Statement: The community randomized study obtained permissions from the Ethical Review Board of Pirkanmaa Hospital District (R07113M 14.6.2007) and the Ethical Review Board of North Bothnia Hospital District (EETTMK:111/2009). Informed consent to use the FMC serum samples for research purposes is granted by the pregnant women when they donate their 1st trimester sample for screening of congenital infections.

Background Human papillomavirus (HPV)-related anal cancer lesions are often found adjacent to the squamocolumnar junction (SCJ). We have assessed the histopathology and associated HPV genotypes in anal SCJ lesions in surgically excised anal warts in HIV-negative and –positive patients. Methods Histopathology identified 47 squamous intraepithelial lesions (SILs) adjacent to the SCJ amongst a total of 145 cases of clinically diagnosed anal condylomata. The anal SCJ lesions were further analyzed with p16, CK7 and p63 immunohistochemistry and HPV genotyping. Results Sixteen (16/47) of the excised anal wart lesions contained HSIL; Three were HSIL and exclusively associated with oncogenic HPVs. A further thirteen (13/47) were mixed lesions. Of these eight were HSILs with LSIL and six were HSILs with papillary immature metaplasia (PIM); Ten of the mixed lesions were associated with one or more oncogenic HPVs, while three cases were exclusively associated with HPV6. Conclusions Clinically diagnosed anal warts cannot be assumed to be limited to low-grade lesions as anal warts of the SCJ often show heterogeneous lesions, with coexistence of LSIL, PIM, and HSIL. Lesions showing PIM, however, may mimic HSIL, because they are hypercellular, but lack the nuclear atypia and conspicuous mitotic activity of HSIL; and are p16 negative., Highlights • Anal warts of the SCJ are often heterogeneous; with LSIL, including PIM and HSIL. • Anal HSILs only with HPV6 may indicate that LR-HPVs have some role in oncogenesis. • Recognition of PIM is important given its potential for being confused with HSIL. • Clinical diagnosis of anal warts cannot be assumed to be limited to LSIL. • Microscopic examination of anal warts is encouraged with appropriate immunostains.

Anal condylomata are common in HIV-positive individuals and among men who have sex with men (MSM). Generally attributable to infection by low-risk human papillomaviruses (HPVs), condylomata are considered benign low-grade squamous intraepithelial lesions (SILs). However, anal condylomata have occasionally been linked to high-grade SIL and to oncogenic, high-risk HPVs. Here we describe the range of intraepithelial lesions and of the associated HPVs in heterosexual men and women and MSM. Perianal and anal condylomata were collected from 243 patients (56 heterosexual women, 61 heterosexual men and 126 MSM, including 41 HIV-positive MSM). We assessed lesion histology and HPV genotype. Prevalence estimates and Poisson models were used. Irrespective of HIV infection status, MSM showed a higher proportion of condylomata as high-grade SILs compared to heterosexual men/women. High-grade SILs were also more prevalent in anal than in perianal lesions in all patient groups. HIV-positive MSM exhibited increased prevalence ratio (4.6; 95% confidence interval 2.1–10.0) of perianal low-grade SILs containing only high-risk HPVs compared to HIV-negative MSM. In addition, more than 64% of anal SILs with a high-grade component, regardless of HIV infection, were exclusively associated with low-risk HPVs. In anal condylomata, both high-grade and low-grade SILs can be associated with high-risk and/or low-risk HPVs. Particularly, low-grade perianal SILs associated with high-risk HPVs were common in HIV-positive MSM, while presence of only low-risk HPVs in high-grade SILs were common in both MSM groups. Our findings sound a note of caution for the common clinical practice for the treatment of anal condylomata as benign lesions in MSM and HIV-positive patients.