BackgroundUnderstanding HIV-1 subtype distribution and epidemiology can assist preventive measures and clinical decisions. Sequence variation may affect antiviral drug resistance development, disease progression, evolutionary rates and transmission routes.ResultsWe investigated the subtype distribution of HIV-1 in Europe and Israel in a representative sample of patients diagnosed between 2002 and 2005 and related it to the demographic data available. 2793 PRO-RT sequences were subtyped either with the REGA Subtyping tool or by a manual procedure that included phylogenetic tree and recombination analysis. The most prevalent subtypes/CRFs in our dataset were subtype B (66.1%), followed by sub-subtype A1 (6.9%), subtype C (6.8%) and CRF02_AG (4.7%). Substantial differences in the proportion of new diagnoses with distinct subtypes were found between European countries: the lowest proportion of subtype B was found in Israel (27.9%) and Portugal (39.2%), while the highest was observed in Poland (96.2%) and Slovenia (93.6%). Other subtypes were significantly more diagnosed in immigrant populations. Subtype B was significantly more diagnosed in men than in women and in MSM > IDUs > heterosexuals. Furthermore, the subtype distribution according to continent of origin of the patients suggests they acquired their infection there or in Europe from compatriots.ConclusionsThe association of subtype with demographic parameters suggests highly compartmentalized epidemics, determined by social and behavioural characteristics of the patients.

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Summary In this review, we systematically searched and summarized the evidence on the immune response and reinfection rate following SARS‐CoV‐2 infection. We also retrieved studies on SARS‐CoV and MERS‐CoV to assess the long‐term duration of antibody responses. A protocol based on Cochrane rapid review methodology was adhered to and databases were searched from 1/1/2000 until 26/5/2020. Of 4744 citations retrieved, 102 studies met our inclusion criteria. Seventy‐four studies were retrieved on SARS‐CoV‐2. While the rate and timing of IgM and IgG seroconversion were inconsistent across studies, most seroconverted for IgG within 2 weeks and 100% (N = 62) within 4 weeks. IgG was still detected at the end of follow‐up (49‐65 days) in all patients (N = 24). Neutralizing antibodies were detected in 92%‐100% of patients (up to 53 days). It is not clear if reinfection with SARS‐CoV‐2 is possible, with studies more suggestive of intermittent detection of residual RNA. Twenty‐five studies were retrieved on SARS‐CoV. In general, SARS‐CoV‐specific IgG was maintained for 1‐2 years post‐infection and declined thereafter, although one study detected IgG up to 12 years post‐infection. Neutralizing antibodies were detected up to 17 years in another study. Three studies on MERS‐CoV reported that IgG may be detected up to 2 years. In conclusion, limited early data suggest that most patients seroconvert for SARS‐CoV‐2‐specific IgG within 2 weeks. While the long‐term duration of antibody responses is unknown, evidence from SARS‐CoV studies suggest SARS‐CoV‐specific IgG is sustained for 1‐2 years and declines thereafter.

Summary Despite over 140 million SARS‐CoV‐2 infections worldwide since the beginning of the pandemic, relatively few confirmed cases of SARS‐CoV‐2 reinfection have been reported. While immunity from SARS‐CoV‐2 infection is probable, at least in the short term, few studies have quantified the reinfection risk. To our knowledge, this is the first systematic review to synthesise the evidence on the risk of SARS‐CoV‐2 reinfection over time. A standardised protocol was employed, based on Cochrane methodology. Electronic databases and preprint servers were searched from 1 January 2020 to 19 February 2021. Eleven large cohort studies were identified that estimated the risk of SARS‐CoV‐2 reinfection over time, including three that enrolled healthcare workers and two that enrolled residents and staff of elderly care homes. Across studies, the total number of PCR‐positive or antibody‐positive participants at baseline was 615,777, and the maximum duration of follow‐up was more than 10 months in three studies. Reinfection was an uncommon event (absolute rate 0%–1.1%), with no study reporting an increase in the risk of reinfection over time. Only one study estimated the population‐level risk of reinfection based on whole genome sequencing in a subset of patients; the estimated risk was low (0.1% [95% CI: 0.08–0.11%]) with no evidence of waning immunity for up to 7 months following primary infection. These data suggest that naturally acquired SARS‐CoV‐2 immunity does not wane for at least 10 months post‐infection. However, the applicability of these studies to new variants or to vaccine‐induced immunity remains uncertain.

In February 2015, an outbreak of recently acquired HIV infections among people who inject drugs (PWID) was identified in Dublin, following similar outbreaks in Greece and Romania in 2011. We compared drug and risk behaviours among 15 HIV cases and 39 controls. Injecting a synthetic cathinone, snow blow, was associated with recent HIV infection (AOR: 49; p=0.003). Prevention and control efforts are underway among PWID in Dublin, but may also be needed elsewhere in Europe.