Vaccination coverage among people who inject drugs: A systematic review.

BACKGROUND: People who inject drugs may be at excess risk of acquiring vaccine-preventable diseases and negative associated health outcomes, but experience barriers to vaccination. We aimed to determine vaccination coverage among people who inject drugs globally. METHODOLOGY: We conducted systematic searches of the peer-reviewed and grey literature, date limited from January 2008 to August 2023, focusing on diseases for which people who inject drugs are at elevated risk for and for which an adult vaccination dose is recommended (COVID-19, hepatitis A, hepatitis B, human papillomavirus, influenza, pneumococcal disease, tetanus). To summarise available data, we conducted a narrative synthesis. RESULTS: We included 78 studies/reports comprising 117 estimates of vaccination coverage across 36 countries. Most estimates were obtained from high income countries (80%, n=94). We located estimates for hepatitis B vaccination in 33 countries, which included 18 countries with data on serological evidence of vaccine-derived hepatitis B immunity (range: 6-53%) and 22 countries with self-report data for vaccine uptake (<1-96%). Data for other vaccines were scarcer: reported hepatitis A vaccination coverage ranged 3-89% (five countries), COVID-19 ranged 4-84% (five countries), while we located estimates from fewer than five countries for influenza, tetanus, pneumococcal disease, and human papillomavirus. CONCLUSION: Estimates were sparse but where available indicative of suboptimal vaccination coverage among people who inject drugs. Improving the consistency, timeliness, and geographic coverage of vaccine uptake data among this population is essential to inform efforts to increase uptake.

High COVID-19 vaccine uptake following initial hesitancy among people in Australia who inject drugs.

BACKGROUND: Previous studies have reported high COVID-19 vaccine hesitancy among people who inject drugs. We aimed to examine COVID-19 vaccine coverage, motivations and barriers to vaccination, and factors associated with uptake among this population in Australia, 1.5 years after vaccine rollout commenced. METHODS: In June-July 2022, 868 people (66.0 % male, mean age 45.6 years) who regularly inject drugs and reside in an Australian capital city reported the number of COVID-19 vaccine doses they had received and their primary motivation (if vaccinated) or barrier (if unvaccinated) to receive the vaccine. We compared vaccine uptake to Australian population estimates and used logistic regression to identify factors associated with ≥ 2 dose and ≥ 3 dose uptake. RESULTS: Overall, 84.1 % (n = 730) had received at least one COVID-19 vaccine dose, 79.6 % (n = 691) had received ≥ 2 doses, and 46.1 % (n = 400) had received ≥ 3 doses. Participants were less likely to be vaccinated than the Australian general population (prevalence ratio: 0.82, 95 % confidence interval [CI]: 0.76-0.88). Key motivations to receive the vaccine were to protect oneself or others from COVID-19, while barriers pertained to vaccine or government distrust. Opioid agonist treatment (adjusted odds ratio [aOR]: 2.49, 95 % CI: 1.44-4.42), current seasonal influenza vaccine uptake (aOR: 6.76, 95 % CI: 3.18-16.75), and stable housing (aOR: 1.58, 95 % CI: 1.02-2.80) were associated with receipt of at least two vaccine doses. Participants aged ≥ 40 years (versus < 40 years; aOR: 1.66, 95 % CI: 1.10-2.53) or who reported a chronic health condition (aOR: 1.71, 95 % CI: 1.18-2.47) had higher odds of receiving at least three vaccine doses. CONCLUSION: We observed higher COVID-19 vaccine uptake than expected given previous studies of vaccine acceptability among people who inject drugs. However, it was lower than the general population. People who inject drugs and reside in unstable housing are a subpopulation that require support to increase vaccine uptake.

Global, regional, and country-level coverage of testing and treatment for HIV and hepatitis C infection among people who inject drugs: a systematic review.

BACKGROUND: People who inject drugs are disproportionately affected by HIV and hepatitis C virus (HCV) infections, while there is little global data on HIV and HCV testing and treatment coverage of this population. We conducted a systematic review to evaluate country-level, regional, and global coverage of HIV and HCV testing and treatment among people who inject drugs. METHODS: We did a systematic review, and searched bibliographic databases (MEDLINE, Embase, and PsycINFO) and grey literature for studies published between Jan 1, 2017, and April 30, 2022, that evaluated the proportion of people who inject drugs who received testing or treatment for HIV or HCV. For each country, we estimated the proportion of people who inject drugs tested for HIV antibodies in the past 12 months (recent), people who inject drugs ever tested for HCV antibodies and HCV RNA, people who inject drugs with HIV currently receiving antiretroviral therapy, and people who inject drugs with HCV ever receiving HCV antiviral treatment. Regional and global estimates, weighted by the population size of people who inject drugs, were generated where sufficient data were available. This study is registered with PROSPERO (CRD42020173974). FINDINGS: 512 documents reported data eligible for analyses, including 337 peer-reviewed articles, 27 conference abstracts or presentations, and 148 documents from grey literature or supplementary searches. Data of recent HIV antibody testing were available for 67 countries and ever having had HCV antibody testing were available for 49 countries. Globally, an estimated 48·8% of people who inject drugs were recently tested for HIV antibodies (95% uncertainty interval [UI] 43·3-54·2%; range 0·9-86·0%), and 47·1% had ever been tested for HCV antibodies (95% UI 43·4-51·0%; range 0·0-93·3%). HCV RNA testing data were available from three countries. Coverage of HIV antibody testing was high (>75%) in four countries and for HCV antibody testing in 15 countries. The estimated uptake of current HIV treatment (18 countries) ranged from 2·6% to 81·9%, and the estimated uptake of ever having HCV treatment (23 countries) ranged from 1·8% to 88·6% across countries. Uptake of HIV treatment was high in two countries, and of HCV treatment in one country. INTERPRETATION: HIV and HCV testing and treatment uptake among people who inject drugs was highly variable, and suboptimal in most countries. Strategies to improve access to HIV and HCV care among people who inject drugs and the availability of public health surveillance are urgently required. FUNDING: Australian National Health and Medical Research Council and UK National Institute for Health and Care Research Health Protection Research Unit in Behavioural Science and Evaluation.

Trends and psychosocial correlates of same day polysubstance use among people who inject drugs in Australia, 2012-2022.

BACKGROUND: Polysubstance use is associated with negative health and social outcomes among people who inject drugs. We aimed to describe trends in polysubstance use and identify psychosocial correlates and associated drug use risk behaviours. We defined polysubstance use as intentional same day use of more than one of three drug classes: opioids, other non-opioid depressants (hereafter 'depressants'), and stimulants. METHODS: We used 10 years (2012-2022, excluding 2020) of data from annual surveys in Australian capital cities with people who inject drugs (N=5657) to construct five mutually exclusive polysubstance use profiles: opioid-depressant, opioid-stimulant, stimulant-depressant, opioid-stimulant-depressant, and single drug class use. We examined time trends using the Mann Kendall test and identified correlates using multinomial logistic regression. RESULTS: Same day polysubstance use was relatively common among this sample (43.6%). Opioid-depressant use was the most frequent polysubstance use profile, but this decreased over the study period (32.6% to 13.3%, p<0.001). This aligned with observed decreases in use of pharmaceutical opioids (p<0.001), opioid agonist treatment (p=0.007), and benzodiazepines (p=0.001). There was no evidence for any trend in the other polysubstance use profiles, although single drug class use increased (51.9% to 64.7%, p=0.031). The different polysubstance use profiles were variously associated with psychosocial factors, including unstable housing and very high psychological distress, and other drug use risk behaviours, including non-fatal overdose, receptive and/or distributive needle sharing, and reusing one's own needles. CONCLUSION: Same day polysubstance use has remained relatively common among this sample over time, although the typology has changed. Collectively, our findings point to diverse drug use patterns among people who inject drugs and reiterate the need for a range of harm reduction, treatment, and support options.

Epidemiology of injecting drug use, prevalence of injecting-related harm, and exposure to behavioural and environmental risks among people who inject drugs: a systematic review.

BACKGROUND: People who inject drugs are exposed to various and changing risk environments and are at risk of multiple harms related to injecting drug use (IDU). We aimed to undertake a global systematic review of the prevalence of IDU, key IDU-related harms (including HIV, hepatitis C virus [HCV], and hepatitis B virus [HBV] infection and overdose), and key sociodemographic characteristics and risk exposures for people who inject drugs. METHODS: We systematically searched for data published between Jan 1, 2017, and March 31, 2022, in databases of peer-reviewed literature (MEDLINE, Embase, and PsycINFO) and grey literature as well as various agency or organisational websites, and disseminated data requests to international experts and agencies. We searched for data on the prevalence, characteristics, and risks of people who inject drugs, including gender, age, sexuality, drug-use patterns, HIV, HCV, and HBV infections, non-fatal overdose, depression, anxiety, and injecting-related disease. Additional data were extracted from studies identified in our previous review. Meta-analyses were used to pool the data where multiple estimates were available for a country. We present country, regional, and global estimates for each variable examined. FINDINGS: We screened 40 427 reports published between 2017 and 2022, and the 871 eligible reports identified were added to the 1147 documents from the previous review. Evidence of IDU was documented in 190 of 207 countries and territories, and 14·8 million people (95% uncertainty interval [UI] 10·0-21·7) aged 15-64 years globally were estimated to inject drugs. Existing evidence suggests that there might be 2·8 million (95% UI 2·4-3·2) women and 12·1 million (95% UI 11·0-13·3) men who inject drugs globally, and that 0·4% (95% CI 0·3-1·3) of people who inject drugs identify as transgender. The amount of available data on key health and social risks among people who inject drugs varied widely across countries and regions. We estimated that 24·8% (95% CI 19·5-31·6) of people who inject drugs globally had experienced recent homelessness or unstable housing, 58·4% (95% CI 52·0-64·8) had a lifetime history of incarceration, and 14·9% (95% CI 8·1-24·3) had recently engaged in sex work, with substantial geographical variation. Injecting and sexual risk behaviour varied considerably geographically, as did risks of harms. Globally, we estimated that 15·2% (95% CI 10·3-20·9) of people who inject drugs are living with HIV, 38·8% (95% CI 31·4-46·9) have current HCV infection, 18·5% (95% CI 13·9-24·1) have recently overdosed, and 31·7% (95% CI 23·6-40·5) have had a recent skin or soft tissue infection. INTERPRETATION: IDU is being identified in a growing number of countries and territories that comprise more than 99% of the global population. IDU-related health harms are common, and people who inject drugs continue to be exposed to multiple adverse risk environments. However, quantification of many of these exposure and harms is inadequate and must be improved to allow for better targeting of harm-reduction interventions for these risks. FUNDING: Australian National Health and Medical Research Council.

Disruption to Australian heroin, methamphetamine, cocaine and ecstasy markets with the COVID-19 pandemic and associated restrictions.

BACKGROUND: Changes to drug markets can affect drug use and related harms. We aimed to describe market trends of heroin, methamphetamine, cocaine and ecstasy in Australia following the introduction of COVID-19 pandemic-associated restrictions. METHODS: Australians residing in capital cities who regularly inject drugs (n ∼= 900 each year) or regularly use ecstasy and/or other illicit stimulants (n ∼= 800 each year) participated in annual interviews 2014-2022. We used self-reported market indicators (price, availability, and purity) for heroin, crystal methamphetamine, cocaine, and ecstasy crystal to estimate generalised additive models. Observations from the 2014-2019 surveys were used to establish the pre-pandemic trend; 2020, 2021 and 2022 observations were considered immediate, short-term and longer-term changes since the introduction of pandemic restrictions. RESULTS: Immediate impacts on market indicators were observed for heroin and methamphetamine in 2020 relative to the 2014-2019 trend; price per cap/point increased (ß: A$9.69, 95% confidence interval [CI]: 2.25-17.1 and ß: A$40.3, 95% CI: 33.1-47.5, respectively), while perceived availability (adjusted odds ratio [aOR] for 'easy'/'very easy' to obtain: 0.38, 95% CI: 0.24-0.59 and aOR: 0.08, 95% CI: 0.03-0.25, respectively) and perceived purity (aOR for 'high' purity: 0.36, 95% CI: 0.23-0.54 and aOR: 0.33, 95% CI: 0.20-0.54, respectively) decreased. There was no longer evidence for change in 2021 or 2022 relative to the 2014-2019 trend. Changes to ecstasy and cocaine markets were most evident in 2022 relative to the pre-pandemic trend: price per gram increased (ß: A$92.8, 95% CI: 61.6-124 and ß: A$24.3, 95% CI: 7.93-40.6, respectively) and perceived purity decreased (aOR for 'high purity': 0.18, 95% CI: 0.09-0.35 and 0.57, 95% CI: 0.36-0.90, respectively), while ecstasy was also perceived as less easy to obtain (aOR: 0.18, 95% CI: 0.09-0.35). CONCLUSION: There were distinct disruptions to illicit drug markets in Australia after the COVID-19 pandemic began; the timing and magnitude varied by drug.

COVID-19 vaccine attitudes and facilitators among people in Australia who inject drugs.

INTRODUCTION: We aimed to describe COVID-19 vaccination attitudes and identify potential facilitators for vaccine uptake among people who inject drugs. METHODS: People who inject drugs were recruited from all eight Australian capital cities (N = 884; 65% male, mean age 44 years) and interviewed face-to-face or via telephone in June-July 2021. COVID-19 and broader vaccination attitudes were used to model latent classes. Correlates of class membership were assessed through multinomial logistic regression. Probability of endorsing potential vaccination facilitators were reported by class. RESULTS: Three classes of participants were identified: 'vaccine acceptant' (39%), 'vaccine hesitant' (34%) and 'vaccine resistant' (27%). Those in the hesitant and resistant groups were younger, more likely to be unstably housed and less likely to have received the current season influenza vaccine than the acceptant group. In addition, hesitant participants were less likely to report a chronic medical condition than acceptant participants. Compared to vaccine acceptant and hesitant participants, vaccine-resistant participants were more likely to predominantly inject methamphetamine and to inject drugs more frequently in the past month. Both vaccine-hesitant and resistant participants endorsed financial incentives for vaccination and hesitant participants also endorsed facilitators related to vaccine trust. DISCUSSION AND CONCLUSION: People who inject drugs who are unstably housed or predominantly inject methamphetamine are subgroups that require targeted interventions to increase COVID-19 vaccination uptake. Vaccine-hesitant people may benefit from interventions that build trust in vaccine safety and utility. Financial incentives may improve vaccine uptake among both hesitant and resistant people.

Antibody titres elicited by the 2018 seasonal inactivated influenza vaccine decline by 3 months post-vaccination but persist for at least 6 months.

BACKGROUND: In Australia, seasonal inactivated influenza vaccine is typically offered in April. However, the onset, peak and end of a typical influenza season vary, and optimal timing for vaccination remains unclear. Here, we investigated vaccine-induced antibody response kinetics over 6 months in different age groups. METHODS: We conducted a prospective serosurvey among 71 adults aged 18-50 years, 15 community-dwelling ('healthy') and 16 aged-care facility resident ('frail') older adults aged ≥65 years who received the 2018 southern hemisphere vaccines. Sera were collected at baseline, and 1, 2, 4, and 6 months post-vaccination. Antibody titres were measured by haemagglutination inhibition or microneutralisation assays. Geometric mean titres were estimated using random effects regression modelling and superimposed on 2014-2018 influenza season epidemic curves. RESULTS: Antibody titres peaked 1.2-1.3 months post-vaccination for all viruses, declined by 3 months post-vaccination but, notably, persisted above baseline after 6 months in all age groups by 1.3- to 1.5-fold against A(H1N1)pdm09, 1.7- to 2-fold against A(H3N2), 1.7- to 2.1-fold against B/Yamagata and 1.8-fold against B/Victoria. Antibody kinetics were similar among different age groups. Antibody responses were poor against cell-culture grown compared to egg-grown viruses. CONCLUSIONS: These results suggest subtype-specific antibody-mediated protection persists for at least 6 months, which corresponds to the duration of a typical influenza season.

Epidemiology of repeat influenza infection in Queensland, Australia, 2005-2017.

Natural infection with the influenza virus is believed to generate cross-protective immunity across both types and subtypes. However, less is known about the persistence of this immunity and thus the susceptibility of individuals to repeat infection. We used 13 years (2005-2017) of surveillance data from Queensland, Australia, to describe the incidence and distribution of repeat influenza infections. Consecutive infections that occurred within 14 days of prior infection were considered a mixed infection; those that occurred more than 14 days later were considered separate (repeat) infections. Kaplan-Meier plots were used to investigate the probability of reinfection over time and the Prentice, Williams and Peterson extension of the Cox proportional hazards model was used to assess the association of age and gender with reinfection. Among the 188 392 notifications received during 2005-2017, 6165 were consecutively notified for the same individual (3.3% of notifications), and 2958 were mixed infections (1.6%). Overall, the probability of reinfection was low: the cumulative incidence was <1% after one year, 4.6% after five years, and 9.6% after ten years. The majority of consecutive infections were the result of two type A infections (43%) and were most common among females (adjusted hazard ratio (aHR): 1.15, 95% confidence interval (CI) 1.09-1.21), children aged less than 5 years (relative to adults aged 18-64 years aHR: 1.58, 95% CI 1.47-1.70) and older adults aged at least 65 years (aHR: 1.35; 95% CI 1.24-1.47). Our study suggests consecutive infections are possible but rare. These findings have implications for our understanding of population immunity to influenza.

Trends in methamphetamine use, markets and harms in Australia, 2003-2019.

INTRODUCTION: To describe trends in methamphetamine use, markets and harms in Australia from 2003 to 2019. METHODS: Data comprised patterns of use and price from sentinel samples of people who inject drugs and who use MDMA/other illicit stimulants and population-level amphetamine-related police seizures, arrests, hospitalisations, treatment episodes and deaths from approximately 2003 to 2019. Bayesian autoregressive time-series models were analysed for: no change; constant rate of change; and change over time differing in rate after one to three changepoints. Related indicators were analysed post hoc with identical changepoints. RESULTS: The percentage of people who inject drugs reporting weekly use increased from 2010 to 2013 onwards, while use among samples of people who regularly use ecstasy and other illicit stimulants decreased. Seizures and arrests rose steeply from around 2009/10 to 2014/15 and subsequently plateaued. Price increased ($15.9 [95% credible interval, CrI $9.9, $28.9] per point of crystal per year) from around 2009 to 2011, plateauing and then declining from around 2017. Hospitalisation rates increased steeply from around 2009/10 until 2015/16, with a small subsequent decline. Treatment also increased (19.8 episodes [95% CrI 13.2, 27.6] with amphetamines as the principal drug of concern per 100 000 persons per year) from 2010/11 onwards. Deaths involving amphetamines increased (0.285 per 100 000 persons per year) from 2012 until 2016. DISCUSSION AND CONCLUSIONS: These findings suggest that problematic methamphetamine use and harms escalated from 2010 to 2012 onwards in Australia, with continued demand and a sustained market for methamphetamine. [Correction added on 30 May 2022, after first online publication: In the Abstract under 'Discussion and Conclusions' 'onwards' has been added after … 2010 to 2012].

Long short-term memory model - A deep learning approach for medical data with irregularity in cancer predication with tumor markers.

BACKGROUND: Machine learning (ML) has emerged as a superior method for the analysis of large datasets. Application of ML is often hindered by incompleteness of the data which is particularly evident when approaching disease screening data due to varied testing regimens across medical institutions. Here we explored the utility of multiple ML algorithms to predict cancer risk when trained using a large but incomplete real-world dataset of tumor marker (TM) values. METHODS: TM screening data were collected from a large asymptomatic cohort (n = 163,174) at two independent medical centers. The cohort included 785 individuals who were subsequently diagnosed with cancer. Data included levels of up to eight TMs, but for most subjects, only a subset of the biomarkers were tested. In some instances, TM values were available at multiple time points, but intervals between tests varied widely. The data were used to train and test various machine learning models to evaluate their robustness for predicting cancer risk. Multiple methods for data imputation were explored and models were developed for both single time-point as well as time-series data. RESULTS: The ML algorithm, long short-term memory (LSTM), demonstrated superiority over other models for dealing with irregular medical data. A cancer risk prediction tool was trained and validated for a single time-point test of a TM panel including up to four biomarkers (AUROC = 0.831, 95% CI: 0.827-0.835) which outperformed a single threshold method using the same biomarkers. A second model relying on time series data of up to four time-points for 5 TMs had an AUROC of 0.931. CONCLUSIONS: A cancer risk prediction tool was developed by training a LSTM model using a large but incomplete real-world dataset of TM values. The LSTM model was best able to handle irregular data compared to other ML models. The use of time-series TM data can further improve the predictive performance of LSTM models even when the intervals between tests vary widely. These risk prediction tools are useful to direct subjects to further screening sooner, resulting in earlier detection of occult tumors.

COVID-19 vaccine acceptability among people in Australia who inject drugs: Update from the 2021 Illicit Drug Reporting System interviews.

People who inject drugs may be at higher risk of COVID-19 transmission and more severe negative health outcomes following COVID-19 infection. Early research on hypothetical COVID-19 vaccines suggests this population may be less likely to accept vaccination. This commentary extends this research by presenting vaccine intention data from Illicit Drug Reporting System interviews conducted in June-July 2021, in the early stages of vaccine rollout, with people in Australia who inject drugs (N = 888). Half the sample (48%, n = 419) reported that they were hesitant to receive the COVID-19 vaccine, with key barriers relating to vaccine safety and side effect concerns. This level of hesitancy is substantially higher than that of the general population at a similar time. While we note that the subsequent Delta variant-driven third wave of cases in Australia and efforts to increase population vaccination coverage may have altered intent in this group, this level of hesitancy warrants a targeted strategy to mitigate vaccine-related concerns and maximise uptake. Ideally, this should comprise an inclusive health response that is peer-led, with peer-based organisations ideally positioned to direct immunisation service delivery and provide vaccine-related messaging.

Changes in illicit drug use and markets with the COVID-19 pandemic and associated restrictions: findings from the Ecstasy and Related Drugs Reporting System, 2016-20.

AIMS: To describe (i) self-reported changes in drug use and (ii) trends in price, perceived availability, and perceived purity of illicit drugs, among people who regularly use ecstasy/ 3,4-methylenedioxymethamphetamine (MDMA) and other illicit stimulants in Australia following COVID-19 and associated restrictions. DESIGN: Annual interviews with cross-sectional sentinel samples conducted face-to-face in 2016-19 and via video conferencing or telephone in 2020. Data were collected via an interviewer-administered structured questionnaire. SETTING: Australian capital cities. PARTICIPANTS: Australians aged 16 years or older who used ecstasy/MDMA and other illicit stimulants on a monthly or more frequent basis and resided in a capital city, recruited via social media and word-of-mouth (n ~ 800 each year). MEASUREMENTS: Key outcome measures were self-reported illicit drug market indicators (price, purity and availability) and, in 2020 only, perceived change in drug use (including alcohol and tobacco) since March 2020 and reasons for this change. FINDINGS: For most drugs, participants reported either no change or a reduction in their use since COVID-19 restrictions were introduced. Ecstasy/MDMA was the drug most frequently cited as reduced in use (n = 552, 70% of those reporting recent use), mainly due to reduced opportunities for socialization. While market indicators were largely stable across most drugs, the odds of perceiving MDMA capsules as 'high' in purity decreased compared with 2016-19 [adjusted odds ratio (aOR) = 0.72, 95% confidence interval (CI) = 0.53-0.99], as did perceiving them as 'easy' to obtain (aOR = 0.42, CI = 0.26-0.67). The odds of perceiving cocaine and methamphetamine crystal as 'easy' to obtain also decreased (aOR = 0.67, CI = 0.46-0.96 and aOR = 0.12, CI = 0.04-0.41, respectively). CONCLUSIONS: After COVID-19-related restrictions were introduced in Australia, use of ecstasy/MDMA, related stimulants and other licit and illicit drugs mainly appeared to remain stable or decrease, primarily due to impediments to socialization.

COVID-19 vaccine acceptability among people in Australia who inject drugs: Implications for vaccine rollout.

INTRODUCTION: Vaccine acceptability is a key determinant of vaccination uptake. Despite being at risk of adverse outcomes from coronavirus-19 disease (COVID-19), COVID-19 vaccine acceptability among people who inject drugs is unknown. We surveyed people who inject drugs in Melbourne, Australia to assess potential uptake of COVID-19 vaccines prior to distribution. METHODS: Cross-sectional study, comprising interviewer-administered structured telephone interviews completed from 30 November to 22 December 2020 in Melbourne, Australia. Participants were people aged 18 years or older who injected drugs at least monthly in the past 6 months and had resided in Melbourne in the past 12 months recruited via needle-syringe programs and word-of-mouth. MEASUREMENTS: COVID-19 hypothetical vaccine acceptability, participants' demographic, drug use and drug treatment characteristics. RESULTS: Fifty-eight percent (57/99) of the sample reported that they would definitely or probably be vaccinated for COVID-19, with the remainder indicating that they would not (22%) or were undecided (20%). Among those who indicated that they would definitely or probably not be vaccinated or were undecided (n = 42), safety concerns were most often cited as a reason for not wanting to be vaccinated. DISCUSSION AND CONCLUSIONS: Although a majority of sampled people who inject drugs indicated that they would definitely or probably be vaccinated, efforts to reduce hesitancy and allay COVID-19 vaccine safety concerns will be necessary to optimise vaccine uptake among this population.

Hepatitis C virus cascade of care among people who inject drugs in Australia: Factors associated with testing and treatment in a universal healthcare system.

BACKGROUND: Understanding factors associated with engagement across the hepatitis C virus (HCV) cascade of care (CoC) among people who inject drugs (PWID) is critical for developing targeted interventions to enhance engagement and further HCV elimination efforts. We describe the CoC among Australian PWID, and identify factors associated with engagement at each stage. METHODS: As part of the 2018 and 2019 Illicit Drug Reporting System, Australians who regularly inject drugs reported lifetime HCV antibody and RNA testing, treatment uptake and completion. Multivariable logistic regression identified characteristics associated with outcomes. RESULTS: Of 1499 participants, 87% reported antibody testing. Of those, 70% reported RNA testing, of whom 60% reported being RNA positive. Among those, 76% reported initiating treatment, 78% of whom completed. Incarceration history (adjusted odds ratio 1.90; 95% confidence interval 1.28-2.82), current opioid agonist treatment (OAT) (1.99; 1.14-3.47), and recent alcohol and other drug (AOD) counselling (2.22; 1.27-3.88) were associated with antibody testing. Incarceration history (1.42; 1.07-1.87), and current OAT (2.07; 1.51-2.86) were associated with RNA testing. Current OAT (1.92; 1.22-3.03) and recent AOD counselling (1.91; 1.16-3.13) were associated with treatment uptake. Methamphetamine as drug injected most often in the last month was associated with reduced odds of antibody (0.41; 0.25-0.66) and RNA testing (0.54; 0.40-0.74), compared to heroin. CONCLUSION: CoC engagement amongst Australian PWID is encouraging, with AOD service engagement associated with testing and treatment. Further efforts to reach those not service engaged, particularly those not receiving OAT or who predominantly inject methamphetamine, are needed to achieve HCV elimination targets.

Profile and correlates of colorimetric reagent kit use among people who use ecstasy/MDMA and other illegal stimulants in Australia.

BACKGROUND: Colorimetric reagent kits can provide information about the compounds present in drug samples. This study aimed to identify patterns and correlates of colorimetric reagent kit use, as well as behavioural outcomes of testing, amongst people who use illegal stimulants in a context that lacks permanent government-sanctioned drug checking services. METHODS: Australians residing in capital cities who reported regularly using ecstasy/MDMA and/or other illegal stimulants ≥monthly in the past six months were recruited via social media and word-of-mouth from April-July 2019 (N = 792). Participants were asked about testing the contents and/or purity of illegal drugs, and features of last colorimetric reagent kit use. Logistic regression identified correlates of last using a kit (referent: no use of drug checking technology to test drug contents/purity in the past year). RESULTS: Over one-third (36%) reported testing drug contents and/or purity; of this group, 86% had last used a colorimetric reagent kit. On the last occasion, 52% reported someone else had conducted testing; 58% said testing occurred <24 h before planned drug use; and 24% reported testing for quantity of a substance. Correlates of drug checking comprised: being younger, male, past six-month use of new psychoactive substances, accessing community-based health services for alcohol or other drug reasons, selling drugs for cash profit, obtaining information from peers who had tried the drug, and searching online for reports of the drug by stamp/appearance. The majority (84%) tested a substance they had been sold and/or given as MDMA; of these, 87% detected MDMA. Of those who expected and detected MDMA, 29% and 11% reported results to their peers and dealer, respectively. CONCLUSION: People who use ecstasy/MDMA and/or other illegal stimulants seek out objective information about substance contents. In countries that lack permanent government-sanctioned drug checking services, it is important to acknowledge that people already engage in drug checking but with suboptimal technologies and without tailored specialist advice and education.

Uptake, barriers and correlates of influenza vaccination among people who inject drugs in Australia.

BACKGROUND: Comorbid chronic health conditions place people who inject drugs (PWID) at risk of severe health outcomes after influenza infection. However, little is known about the uptake, barriers and correlates of influenza vaccination among PWID. METHODS: During structured surveys, 872 PWID reported whether they had received an influenza vaccination during the last year (disaggregated as pre- or post-March 2020 to ascertain current season vaccine uptake), and if not, the barriers to vaccination. Logistic regression was used to examine demographic, drug use, health and service engagement correlates of vaccine uptake. RESULTS: Thirty-nine percent of participants reported past-year influenza vaccination, with one-quarter (24 %) vaccinated in the current season. The main barriers to vaccination were motivation-based, with few citing issues relating to affordability, supply or perceived stigma. Opioid agonist therapy in the past six months was significantly associated with vaccination. CONCLUSIONS: Influenza vaccine uptake was lower among PWID than the Australian general population. Provision of the vaccine at services commonly accessed by PWID may increase uptake.

Trends in cocaine use, markets and harms in Australia, 2003-2019.

INTRODUCTION: This paper aims to describe cocaine use, markets and harms in Australia from 2003 to 2019. METHODS: Outcome indicators comprised prevalence of use from triennial household surveys; patterns of use from annual surveys of sentinel samples who use stimulants; and cocaine-related seizures, arrests, hospitalisations, deaths and treatment episodes. Bayesian autoregressive time-series analyses were conducted to estimate trend over time: Model 1, no change; Model 2, constant rate of change; and Model 3, change over time differing in rate after one change point. RESULTS: Past-year population prevalence of use increased over time. The percentage reporting recent use in sentinel samples increased by 6.1% (95% credible interval [CrI95% ] 1.2%,16.9%; Model 3) per year from around 2017 (48%) until the end of the series (2019: 67%). There was a constant annual increase in number of seizures (count ratio: 1.1, CrI95% 1.1,1.2) and arrests (1.2, CrI95% 1.1,1.2), and percentage reporting cocaine as easy to obtain in the sentinel samples (percent increase 1.2%, CrI95% 0.5%,1.8%; Model 2). Cocaine-related hospitalisation rate increased from 5.1 to 15.6 per 100 000 people from around 2011-2012 to 2017-2018: an annual increase of 1.3 per 100 000 people (CrI95% 0.8,1.8; Model 3). While the death rate was low (0.23 cocaine-related deaths per 100 000 people in 2018; Model 2), treatment episodes increased from 3.2 to 5.9 per 100 000 people from around 2016-2017 to 2017-2018: an annual increase of 2.9 per 100 000 people (CrI95% 1.6,3.7; Model 3). DISCUSSION AND CONCLUSIONS: Cocaine use, availability and harm have increased, concentrated in recent years, and accompanied by increased treatment engagement.

Epidemiological and cohort study finds no association between COVID-19 and Guillain-Barré syndrome.

Reports of Guillain-Barré syndrome (GBS) have emerged during the Coronavirus disease 2019 (COVID-19) pandemic. This epidemiological and cohort study sought to investigate any causative association between COVID-19 infection and GBS. The epidemiology of GBS cases reported to the UK National Immunoglobulin Database was studied from 2016 to 2019 and compared to cases reported during the COVID-19 pandemic. Data were stratified by hospital trust and region, with numbers of reported cases per month. UK population data for COVID-19 infection were collated from UK public health bodies. In parallel, but separately, members of the British Peripheral Nerve Society prospectively reported incident cases of GBS during the pandemic at their hospitals to a central register. The clinical features, investigation findings and outcomes of COVID-19 (definite or probable) and non-COVID-19 associated GBS cases in this cohort were compared. The incidence of GBS treated in UK hospitals from 2016 to 2019 was 1.65-1.88 per 100 000 individuals per year. GBS incidence fell between March and May 2020 compared to the same months of 2016-19. GBS and COVID-19 incidences during the pandemic also varied between regions and did not correlate with one another (r = 0.06, 95% confidence interval: -0.56 to 0.63, P = 0.86). In the independent cohort study, 47 GBS cases were reported (COVID-19 status: 13 definite, 12 probable, 22 non-COVID-19). There were no significant differences in the pattern of weakness, time to nadir, neurophysiology, CSF findings or outcome between these groups. Intubation was more frequent in the COVID-19 affected cohort (7/13, 54% versus 5/22, 23% in COVID-19-negative) attributed to COVID-19 pulmonary involvement. Although it is not possible to entirely rule out the possibility of a link, this study finds no epidemiological or phenotypic clues of SARS-CoV-2 being causative of GBS. GBS incidence has fallen during the pandemic, which may be the influence of lockdown measures reducing transmission of GBS inducing pathogens such as Campylobacter jejuni and respiratory viruses.