WHO International Standards for antibodies to HPV6 HPV11 HPV31 HPV33 HPV45 HPV52 and HPV58.

Previously established World Health Organization (WHO) International Standards (IS) for anti-HPV16 and HPV18 antibodies are used to harmonize results across human papillomavirus (HPV) serology assays. Here, we present an international collaborative study to establish ISs for antibodies against HPV6 (NIBSC code 19/298), HPV11 (20/174), HPV31 (20/176), HPV33 (19/290), HPV45 (20/178), HPV52 (19/296) and HPV58 (19/300). The candidate standards were prepared using sera from naturally infected individuals. Each candidate was shown to be monospecific for reactivity against its indicated HPV type except for the HPV11 candidate, which was also reactive against other types. Expression of antibody levels relative to the relevant candidate IS reduced inter-laboratory variation allowing greater comparability between laboratories. Based on these results, the WHO Expert Committee on Biological Standardization established each of the 7 candidates as the 1st IS for antiserum to its indicated HPV type for use in the standardization of HPV pseudovirion-based neutralization and antibody-binding assays.

Lack of detectable HPV18 antibodies in 14% of quadrivalent vaccinees in a longitudinal cohort study.

Although HPV vaccines are highly efficacious, a notable proportion of quadrivalent vaccinees are HPV18 seronegative post-vaccination. We have investigated this findings' validity by comparing vaccine-induced antibody responses using two different immunoassays. 6558 16-17-year-old females participated in the FUTURE II (NCT00092534) and PATRICIA (NCT00122681) trials in 2002-2004. Both the quadrivalent and bivalent vaccine recipients (QVR and BVR) received three doses. Twelve-year follow-up for 648 vaccinees was conducted by the Finnish Maternity Cohort. The presence of neutralising and binding HPV antibodies was analysed via HPV pseudovirion-based neutralisation and pseudovirion-binding assays. Four percent and 14.3% of the QVRs were seronegative for neutralising and binding antibodies to HPV16 and HPV18, respectively. No BVRs were HPV16/18 seronegative post-vaccination. The antibody titres were strongly correlated between the assays, Pearson's correlation coefficient, r[HPV16] = 0.92 and 0.85, and r[HPV18] = 0.91 and 0.86 among the QVRs and BVRs respectively. Fourteen percent of QVRs lacked detectable HPV18 antibodies in long-term follow-up.

Human papillomavirus negative high grade cervical lesions and cancers: Suggested guidance for HPV testing quality assurance.

BACKGROUND: Some high-grade cervical lesions and cervical cancers (HSIL+) test negative for human papillomavirus (HPV). The HPV-negative fraction varies between 0.03 % and 15 % between different laboratories. Monitoring and extended re-analysis of HPV-negative HSIL+ could thus be helpful to monitor performance of HPV testing services. We aimed to a) provide a real-life example of a quality assurance (QA) program based on re-analysis of HPV-negative HSIL+ and b) develop international guidance for QA of HPV testing services based on standardized identification of apparently HPV-negative HSIL+ and extended re-analysis, either by the primary laboratory or by a national HPV reference laboratory (NRL). METHODS: There were 116 initially HPV-negative cervical specimens (31 histopathology specimens and 85 liquid-based cytology samples) sent to the Swedish HPV Reference Laboratory for re-testing. Based on the results, an international QA guidance was developed through an iterative consensus process. RESULT: Standard PCR testing detected HPV in 55.2 % (64/116) of initially "HPV-negative" samples. Whole genome sequencing of PCR-negative samples identified HPV in an additional 7 samples (overall 61.2 % HPV positivity). Reasons for failure to detect HPV in an HSIL+ lesion are listed and guidance to identify cases for extended re-testing, including which information should be included when referring samples to an NRL are presented. CONCLUSION: Monitoring the proportion of and reasons for failure to detect HPV in HSIL+ will help support high performance and quality improvement of HPV testing services. We encourage implementation of QA strategies based on re-analysis of "HPV negative" HSIL+ samples.

The International Human Papillomavirus Reference Center: Standardization, collaboration, and quality assurance in HPV research and diagnostics.

The International Human Papillomavirus (HPV) Reference Center (IHRC) confirms and assigns type numbers to novel HPV types, maintains a reference clone repository, and issues international proficiency panels for HPV screening and genotyping. Furthermore, the Center coordinates the Global HPV Reference Laboratory Network that promotes collaboration and international exchange of experiences among national HPV reference laboratories, to further international standardization and quality assurance in the HPV field. The established HPV types (n = 225) belong to 5 different genera: alpha (n = 65), beta (n = 54), gamma (n = 102), mu (n = 3) and nu (n = 1). Since the last published IHRC overview in 2018, 6 novel types have been established, with 5/6 belonging to the gamma genus and 1/6 to beta genus. Also, 474 reference clones have been provided to 55 different research laboratories and the global proficiency program for HPV genotyping has seen an increasing proficiency (despite a decrease seen in 2019), from 68% proficiency in 2017 to 77.3% in 2022. The first proficiency study for HPV screening found an international proficiency of up to 77%. In summary, increasing complexity of the HPVs and demands on quality assurance in the era of cervical cancer elimination requires international efforts to support proficiency and recognized quality and order among HPV types.

Impact of cervical screening by human papillomavirus genotype: Population-based estimations.

BACKGROUND: Cervical screening programs use testing for human papillomavirus (HPV) genotypes. Different HPV types differ greatly in prevalence and oncogenicity. We estimated the impact of cervical screening and follow-up for each HPV type. METHODS AND FINDINGS: For each type of HPV, we calculated the number of women needed to screen (NNS) and number of women needing follow-up (NNF) to detect or prevent one cervical cancer case, using the following individual level input data (i) screening and cancer data for all women aged 25 to 80 years, resident in Sweden during 2004 to 2011 (N = 3,568,938); (ii) HPV type-specific prevalences and screening histories among women with cervical cancer in Sweden in 2002 to 2011(N = 4,254); (iii) HPV 16/18/other HPV prevalences in the population-based HPV screening program (N = 656,607); and (iv) exact HPV genotyping in a population-based cohort (n = 12,527). Historical screening attendance was associated with a 72% reduction of cervical cancer incidence caused by HPV16 (71.6%, 95% confidence interval (CI) [69.1%, 73.9%]) and a 54% reduction of cancer caused by HPV18 (53.8%, 95% CI [40.6%, 63.1%]). One case of HPV16-caused cervical cancer could be prevented for every 5,527 women attending screening (number needed to screen, NNS). Prevention of one case of HPV16-caused cervical cancer required follow-up of 147 HPV16-positive women (number needed to follow-up, NNF). The NNS and NNF were up to 40 to 500 times higher for HPV types commonly screened for with lower oncogenic potential (HPV35,39,51,56,59,66,68). For women below 30 years of age, NNS and NNF for HPV16 were 4,747 and 289, respectively, but >220,000 and >16,000 for HPV35,39,51,56,59,66,68. All estimates were either age-standarized or age-stratified. The primary limitation of our study is that NNS is dependent on the HPV prevalence that can differ between populations and over time. However, it can readily be recalculated in other settings and monitored when HPV type-specific prevalence changes. Other limitations include that in some age groups, there was little data and extrapolations had to be made. Finally, there were very few cervical cancer cases associated with certain HPV types in young age group. CONCLUSIONS: In this study, we observed that the impact of cervical cancer screening varies depending on the HPV type screened for. Estimating and monitoring the impact of screening by HPV type can facilitate the design of effective and efficient HPV-based cervical screening programs. TRIAL REGISTRATION: ClinicalTrials.gov with numbers NCT00479375, NCT01511328.

First international proficiency study on human papillomavirus testing in cervical cancer screening.

BACKGROUND: Although cervical screening using Human Papillomavirus (HPV) testing is globally recommended public health policy, there has been no international proficiency studies specifically targeting HPV testing for cervical screening. OBJECTIVE: To obtain the first global overview of the current proficiency of HPV testing services for cervical cancer screening. STUDY DESIGN: A coded proficiency panel of 12 samples containing HPV types 16, 18, 31, 33, 45, 52, 58 or 35/39/51/56/59/68 in human DNA in varying amounts as well as control. Datasets detecting at least a) 10 International Units (IU) of HPV16 and 18, b) 1000 IU of HPV types 31, 33, 45, 52, 58 and c) having no false positives were considered proficient. RESULTS: In total, 84 laboratories worldwide submitted 158 datasets (some laboratories used >1 HPV testing platform). Of those, 122 (77%) were 100% proficient. Only 14/158 datasets (9%) contained false positive results. Comparison of results with assays approved by the Food and Drug Administration (FDA) suggest that future proficiency requirements should also accommodate assays detecting only 100 IU of HPV16/18. A pool of low oncogenicity HPV types that contributed very little to sensitivity, but adversely affected specificity, was detectable by most datasets. CONCLUSION: Internationally recognized proficiency studies of HPV screening, traceable to international standards, provided an overview of current testing performance. There was a high level of proficiency in terms of sensitivity and few false positives, but specificity was not optimal and further research on optimal specificity of HPV screening tests may be warranted.

An update on one-dose HPV vaccine studies, immunobridging and humoral immune responses - A meeting report.

The 12th HPV Prevention and Control meeting was held on June 2-3, 2022, in Antwerp, Belgium. This technical meeting focused on several topics. This report summarises the discussions and lessons learned on two topics: an update on one-dose HPV vaccination studies and humoral immune responses upon HPV vaccination. Long-term follow-up studies from Costa Rica (eleven years) and India (ten years) report stable levels of antibodies after a single HPV vaccination. High vaccine effectiveness against incident persistent HPV 16/18 infection was seen in India (95.4%, 85.0-99.9) ten years postvaccination and in Kenya (97.5%, 81.7-99.7) eighteen months postvaccination, an important observation in a setting with a higher HPV prevalence. The potential impact of HPV vaccination using a one-dose schedule in India was modelled and showed that implementation of one-dose schedule can contribute towards achieving WHO Cervical Cancer elimination goals. These data support the WHO SAGE recommendations for adopting a one-dose schedule for females aged 9-20 years. Immunobridging studies were discussed during the meeting. General agreement was reached that when thoughtfully applied, they can support and accelerate the expanded use of HPV vaccine with new vaccine schedules, age cohorts, or vaccine formulations. Internationally standardised measurements of HPV immune responses important for the progress of HPV vaccinology field. Humoral immune responses upon HPV vaccination plateau at 24 months regardless of number of doses, therefore, data should be analysed after at least 24 months of follow-up to bridge studies accurately.

Improving human papillomavirus (HPV) testing in the cervical cancer elimination era: The 2021 HPV LabNet international proficiency study.

BACKGROUND: Proficient Human Papillomavirus (HPV) genotyping services are essential to support HPV and cervical cancer elimination strategies, in particular to support HPV vaccine research. OBJECTIVES: To perform a global HPV genotyping proficiency study, with evaluation in relation to previous proficiency studies. STUDY DESIGN: The proficiency panel contained 44 coded samples (40 samples containing one or more purified HPV types (HPV6/11/16/18/31/33/35/39/45/51/52/56/58/59/68a/68b) in human DNA, 1 human DNA control and 3 DNA extraction controls). Proficiency required detection of both single and multiple infections of 50 International Units of HPV 16/18, of 500 genome equivalents for other HPV types and no false positivity. RESULTS: One hundred and thirty-two laboratories submitted 211 datasets. Most assays used (182/211 datasets) were commercially available. An all-time high of 75% of the datasets were 100% proficient. One or more false positives were found in 17.5% of datasets. Among laboratories who participated in the 2019 proficiency study, full proficiency increased from 25% in 2019 to 60% in 2021. The high overall proficiency was mostly attributable to a large number of new laboratories, which used similar assays. CONCLUSIONS: The worldwide deterioration in comparability and reliability of HPV testing found in 2019 is now reversed and an overall increase in proficiency is found.

Head-to-Head Comparison of Bi- and Nonavalent Human Papillomavirus Vaccine-Induced Antibody Responses.

For head-to-head comparison of human papillomavirus (HPV) antibody levels induced by different vaccines, 25-year-old vaccine-naive women were given either the bivalent (n = 188) or the nonavalent HPV vaccine (n = 184). Six months after vaccination antibodies against pseudovirions from 17 different HPV types (HPV6/11/16/18/31/33/35/39/45/51/52/56/58/59/66/68/73) were measured. Antibodies against HPV16/18 were higher after bivalent HPV vaccination (mean international units [IU] 1140.1 and 170.5 for HPV16 and 18, respectively) than after nonavalent vaccination (265.1 and 22.3 IUs, respectively). The bivalent vaccine commonly induced antibodies against the nonvaccine HPV types 31/33/35/45 or 58. The nonavalent vaccine induced higher antibodies against HPV6/11/31/33/45/52/58 and 35.

Human Papillomavirus Infection Determines Prognosis in Cervical Cancer.

PURPOSE: Detection of human papillomavirus (HPV) by polymerase chain reaction in invasive cervical cancer is strongly associated with prognosis but previous studies have not considered sequencing efforts. We aimed to assess the association when also including comprehensive analysis of HPV infection by deep sequencing and a longer follow-up period. MATERIALS AND METHODS: We subjected all 392 of 2,845 invasive cervical cancer cases that were polymerase chain reaction-negative for HPV to RNA sequencing on the NovaSeq 6000 platform (Illumina) and identified an additional 169 cases as HPV-positive. We followed all women from date of diagnosis to December 31, 2016, emigration, or death, whichever occurred first. The main outcome was all-cause mortality by December 31, 2016. We calculated 5-year cumulative relative survival ratios compared with the female general population and used Poisson regression to estimate excess hazard ratios of all-cause mortality by infection with any of the 13 most oncogenic (high-risk [hr]) HPV types in the tumor. All models were adjusted for age, time since diagnosis, stage, histology, and education level. RESULTS: The 5-year cumulative relative survival ratio was 0.45 (95% CI, 0.39 to 0.51) in the hrHPV-negative group, and 0.74 (95% CI, 0.72 to 0.75) in the hrHPV-positive group. This translated to a statistically significantly 43% lower excess mortality in the hrHPV-positive group compared with the hrHPV-negative (corresponding to an excess hazard ratio 0.57; 95% CI, 0.48 to 0.69). There was no association between HPV risk group, clade, or number of HPV infections and prognosis. CONCLUSION: hrHPV status is a strong determinant of cervical cancer prognosis over 15 years after diagnosis, above and beyond other established factors.

Human Papillomavirus (HPV) seroprevalence, cervical HPV prevalence, genotype distribution and cytological lesions in solid organ transplant recipients and immunocompetent women in Sao Paulo, Brazil.

INTRODUCTION: Solid organ transplant (SOT) recipients are at increased risk of Human Papillomavirus (HPV) persistent infection and disease. This study aimed to evaluate HPV seroprevalence, cervical HPV prevalence, genotype distribution, and frequency of HPV-related cervical lesions in SOT recipients in comparison to immunocompetent women. METHODS: Cross-sectional study including SOT and immunocompetent women aged 18 to 45 years who denied previous HPV-related lesions. Cervical samples were screened for HPV-DNA by a polymerase chain reaction (PCR)-based DNA microarray system (PapilloCheck®) and squamous intraepithelial lesions (SIL) by liquid-based cytology. A multiplexed pseudovirion-based serology assay (PsV-Luminex) was used to measure HPV serum antibodies. RESULTS: 125 SOT and 132 immunocompetent women were enrolled. Cervical samples were collected from 113 SOT and 127 immunocompetent women who had initiated sexual activity. HPV-DNA prevalence was higher in SOT than in immunocompetent women (29.6% vs. 20.2%, p = 0.112), but this difference was not statistically significant. High-risk (HR)-HPV was significantly more frequent in SOT than in immunocompetent women (19.4% vs. 7.9%, p = 0.014). Simultaneous infection with ≥2 HR-HPV types was found in 3.1% of SOT and 0.9% of immunocompetent women. HPV seropositivity for at least one HPV type was high in both groups: 63.8% of 105 SOT and 69.7% of 119 immunocompetent women (p = 0.524). Low-grade (LSIL) and high-grade SIL (HSIL) were significantly more frequent in SOT (9.7% and 5.3%, respectively) than in immunocompetent women (1.6% and 0.8%, respectively) (p = 0.001). CONCLUSIONS: These results may reflect the increased risk of HPV persistent infection and disease progression in SOT women due to chronic immunosuppression.

Nonvaccine human papillomavirus genotype common in women with HIV failing cervical precancer treatment.

OBJECTIVE: The aim of this study was to assess failure after treatment of high-grade cervical intraepithelial neoplasia (CIN2+) by HIV status and human papillomavirus (HPV) type. DESIGN: A population-based register study. METHODS: The Swedish National HIV Registry, the Swedish Population Registry and the Swedish National Cervical Screening Registry were linked to identify all women in Stockholm and Gothenburg counties (Sweden) living with HIV and diagnosed with CIN2+ sometime between 1983 and 2014 (n = 179). HIV-negative controls with CIN2+, were matched (2 : 1) for country of birth. CIN2+ biopsies were retrieved from biobanks and genotyped. Absolute risk and adjusted odds ratios (adjOR) of treatment failure by HIV status given HPV type (HPV16/18 vs. non-HPV16/18) were calculated. RESULTS: HPV16 (32%) and HPV35 (24%) dominated in women living with HIV (WLWH) with failure, HPV35 mainly in women born in sub-Saharan Africa (67%). The absolute risk of failure in women with HPV16/18 was 26% [95% confidence interval (95% CI) 14-44] in WLWH and 12% in HIV-negative (95% CI 7-19). The absolute risk of failure in women with non-HPV16/18 was 20% (95% CI 12-31) in WLWH and 5% in HIV-negative (95% CI 2-11). WLWH with non-HPV16/18 were six times more likely to fail than HIV-negative (adjOR 6.1, 95% CI 2.0-18.6). CONCLUSION: HPV35, not included in current HPV vaccines, was the second most common type in WLWH with failure. WLWH with non-HPV16/18 were six times more likely to fail than HIV-negative. This could have implications for surveillance and vaccination post CIN2+ treatment, particularly in WLWH from sub-Saharan Africa.

Organized primary human papillomavirus-based cervical screening: A randomized healthcare policy trial.

BACKGROUND: Clinical trials in the research setting have demonstrated that primary human papillomavirus (HPV)-based screening results in greater protection against cervical cancer compared with cytology, but evidence from real-life implementation was missing. To evaluate the effectiveness of HPV-based cervical screening within a real-life screening program, the organized, population-based cervical screening program in the capital region of Sweden offered either HPV- or cytology-based screening in a randomized manner through a randomized healthcare policy (RHP). METHODS AND FINDINGS: A total of 395,725 women aged 30 to 64 years that were invited for their routine cervical screening visit were randomized without blinding to either cytology-based screening with HPV triage (n = 183,309) or HPV-based screening, with cytology triage (n = 212,416 women) between September 1, 2014 and September 30, 2016 and follow-up through June 30, 2017. The main outcome was non-inferior detection rate of cervical intraepithelial neoplasia grade 2 or worse (CIN2+). Secondary outcomes included superiority in CIN2+ detection, screening attendance, and referral to histology. In total, 120,240 had a cervical screening sample on record in the study period in the HPV arm and 99,340 in the cytology arm and were followed for the outcomes of interest. In per-protocol (PP) analyses, the detection rate of CIN2+ was 1.03% (95% confidence interval (CI) 0.98 to 1.10) in the HPV arm and 0.93% (0.87 to 0.99) in the cytology arm (p for non-inferiority <0.0001; odds ratio (OR) 1.11 (95% CI 1.02 to 1.22)). There were 46 cervical cancers detected in the HPV arm (0.04% (0.03 to 0.06)) and 48 cancers detected in the cytology arm (0.05% (0.04 to 0.07)) (p for non-inferiority <0.0001; OR 0.79 (0.53 to 1.18)). Intention-to-screen (ITS) analyses found few differences. In the HPV arm, there was a modestly increased attendance after new invitations (68.56% (68.31 to 68.80) vs. 67.71% (67.43 to 67.98); OR 1.02 (1.00 to 1.03)) and increased rate of referral with completed biopsy (3.89% (3.79 to 4.00) vs. 3.53% (3.42 to 3.65); OR 1.10 (1.05 to 1.15)). The main limitations of this analysis are that only the baseline results are presented, and there was an imbalance in invitations between the study arms. CONCLUSIONS: In this study, we observed that a real-life RHP of primary HPV-based screening was acceptable and effective when evaluated against cytology-based screening, as indicated by comparable participation, referral, and detection rates. TRIAL REGISTRATION: ClinicalTrials.gov NCT01511328.

Systematic evaluation of SARS-CoV-2 antigens enables a highly specific and sensitive multiplex serological COVID-19 assay.

OBJECTIVE: The COVID-19 pandemic poses an immense need for accurate, sensitive and high-throughput clinical tests, and serological assays are needed for both overarching epidemiological studies and evaluating vaccines. Here, we present the development and validation of a high-throughput multiplex bead-based serological assay. METHODS: More than 100 representations of SARS-CoV-2 proteins were included for initial evaluation, including antigens produced in bacterial and mammalian hosts as well as synthetic peptides. The five best-performing antigens, three representing the spike glycoprotein and two representing the nucleocapsid protein, were further evaluated for detection of IgG antibodies in samples from 331 COVID-19 patients and convalescents, and in 2090 negative controls sampled before 2020. RESULTS: Three antigens were finally selected, represented by a soluble trimeric form and the S1-domain of the spike glycoprotein as well as by the C-terminal domain of the nucleocapsid. The sensitivity for these three antigens individually was found to be 99.7%, 99.1% and 99.7%, and the specificity was found to be 98.1%, 98.7% and 95.7%. The best assay performance was although achieved when utilising two antigens in combination, enabling a sensitivity of up to 99.7% combined with a specificity of 100%. Requiring any two of the three antigens resulted in a sensitivity of 99.7% and a specificity of 99.4%. CONCLUSION: These observations demonstrate that a serological test based on a combination of several SARS-CoV-2 antigens enables a highly specific and sensitive multiplex serological COVID-19 assay.

Multianalyte serology in home-sampled blood enables an unbiased assessment of the immune response against SARS-CoV-2.

Serological testing is essential to curb the consequences of the COVID-19 pandemic. However, most assays are still limited to single analytes and samples collected within healthcare. Thus, we establish a multianalyte and multiplexed approach to reliably profile IgG and IgM levels against several versions of SARS-CoV-2 proteins (S, RBD, N) in home-sampled dried blood spots (DBS). We analyse DBS collected during spring of 2020 from 878 random and undiagnosed individuals from the population in Stockholm, Sweden, and use classification approaches to estimate an accumulated seroprevalence of 12.5% (95% CI: 10.3%-14.7%). This includes 5.4% of the samples being IgG+IgM+ against several SARS-CoV-2 proteins, as well as 2.1% being IgG-IgM+ and 5.0% being IgG+IgM- for the virus' S protein. Subjects classified as IgG+ for several SARS-CoV-2 proteins report influenza-like symptoms more frequently than those being IgG+ for only the S protein (OR = 6.1; p < 0.001). Among all seropositive cases, 30% are asymptomatic. Our strategy enables an accurate individual-level and multiplexed assessment of antibodies in home-sampled blood, assisting our understanding about the undiagnosed seroprevalence and diversity of the immune response against the coronavirus.

The 2019 HPV Labnet international proficiency study: Need of global Human Papillomavirus Proficiency Testing.

BACKGROUND: Accurate and internationally comparable human papillomavirus (HPV) testing services are essential for cervical cancer elimination programs. The WHO HPV Laboratory Network started issuing international HPV testing proficiency panels in 2008. OBJECTIVES: We report the results of the 2019 global proficiency study and evaluate the proficiency over time. STUDY DESIGN: The proficiency panel contained 40 coded samples containing mixes of purified HPV types (HPV6/11/16/18/31/33/35/39/45/51/52/56/58/59/68a/68b) and 4 controls. Proficiency required detection of both single and multiple infections of 50 International Units of HPV 16/18, of 500 genome equivalents (10x higher concentration) for other HPV types, and no false positives (stricter requirement compared to previous panels). RESULTS: Seventy-eight laboratories submitted 110 datasets with 38 different assays. Most samples (38/44) were reported with 100% proficiency in most datasets. Mostly commercial assays were used (88/110 datasets). Overall, 47.3% of the datasets were 100% proficient. False positivity was detected in at least one sample in 30.1% of datasets. When analysing all datasets ever since 2008 using exactly the same proficiency criteria, there was a steady improvement up to 2017 (the proportion of datasets being completely proficient increased from 25% to 73%). However, in the 2019 proficiency testing the proportion of fully proficient datasets dropped to 50%. CONCLUSIONS: Although we initially documented a worldwide improvement in comparability and reliability of HPV testing services, the trend now appears to be reversed. In response, the International HPV Reference Center will provide support for improved quality of laboratory services, including issuing of global proficiency panels every year.

Misclassifications in human papillomavirus databases.

We assessed the quality of human papillomavirus (HPV) sequences in GenBank by analyzing the possible presence of chimeras, "wrong-assembled" contigs and errors in taxonomy using an open-source script (HPVChimera_Gb) that compared 25 638 HPV-related nucleotide sequences in GenBank with the 221 numbered HPV types and another 220 complete HPV sequences. There were 110 sequences with taxonomy/naming errors (sequences reported as another HPV type than the one they corresponded to) and 1318 possibly chimeric sequences. Manual analysis found plausible explanations for most of them (e.g. sequence covering an integration site) but 114 sequences appeared to be chimeras (96/114 were already flagged as "unverified" by GenBank) and 13 had taxonomy/naming errors. When comparing all correct HPV sequences in GenBank, there appeared to exist about 800 unique putative HPV types. Systematic and regular work towards eliminating chimeric sequences and taxonomy/naming errors could increase the quality and order in HPV research.

Antibodies to SARS-CoV-2 and risk of past or future sick leave.

The extent that antibodies to SARS-CoV-2 may protect against future virus-associated disease is unknown. We invited all employees (n = 15,300) at work at the Karolinska University Hospital, Stockholm, Sweden to participate in a study examining SARS-Cov-2 antibodies in relation to registered sick leave. For consenting 12,928 healthy hospital employees antibodies to SARS-CoV-2 could be determined and compared to participant sick leave records. Subjects with viral serum antibodies were not at excess risk for future sick leave (adjusted odds ratio (OR) controlling for age and sex: 0.85 [95% confidence interval (CI) (0.85 (0.43-1.68)]. By contrast, subjects with antibodies had an excess risk for sick leave in the weeks prior to testing [adjusted OR in multivariate analysis: 3.34 (2.98-3.74)]. Thus, presence of viral antibodies marks past disease and protection against excess risk of future disease. Knowledge of whether exposed subjects have had disease in the past or are at risk for future disease is essential for planning of control measures.Trial registration: First registered on 02/06/20, ClinicalTrials.gov NCT04411576.

High Amounts of SARS-CoV-2 Precede Sickness Among Asymptomatic Health Care Workers.

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.