Research on post-vaccination antibody dynamics has become pivotal in estimating COVID-19 vaccine efficacy. We studied anti-SARS-CoV-2 Spike RBD IgG levels in 587 healthcare workers (2038 sera) who completed BNT162b2 vaccination. Average antibody titer 3 weeks after the first dose in COVID-19-naïve participants (median 873.5 AU/mL) was 18-fold higher than the test threshold, with a significant increase 1 month (median 9927.2 AU/mL) and an exponential decrease 3 (median 2976.7 AU/mL) and 6 (median 966.0 AU/mL) months after complete vaccination. Participants with a history of COVID-19 prior to vaccination showed significantly higher antibody levels, particularly after the first dose (median 14,280.2 AU/mL), with a slight decline 1 month (median 12,700.0 AU/mL) and an exponential decline in antibody titers 3 (median 4831.0 AU/mL) and 6 (median 1465.2 AU/mL) months after vaccination. Antibody levels of COVID-19-naïve subjects after the first dose were moderately correlated with age (r = −0.4). Multivariate analysis showed a strong independent correlation between IgG levels 6 months after vaccination and both IgG titers after the first dose and 1 month after vaccination (R2 = 0.709). Regardless of pre-vaccination COVID-19 history, IgG levels 6 months after vaccination were comparable to antibody levels reached by COVID-19-naïve participants after the first vaccine dose.

Introduction: West Nile virus (WNV) immunoglobulin M (IgM) antibodies have been shown to persist for up to 500 days in certain patients. To evaluate the usefulness of immunoglobulin G (IgG) avidity assessment in the diagnosis of WNV infection, we analyzed 54 WNV IgM-and/or IgG-positive serum samples from 39 patients with neuroinvasive disease and 15 asymptomatic cases tested during a seroprevalence investigation. Methods: Serological tests (WNV IgM/IgG antibody detection, IgG avidity) were performed using commercially available enzyme-linked immunosorbent assays. Results: WNV IgM antibodies were detected in 47 (87%) samples. Acute/recent WNV infection was confirmed based on low/borderline avidity index (AI) in 44 IgM-positive samples (93.6%). In three IgM-positive samples (6.4%), high IgG AIs were detected, thus indicating persisting IgM antibodies from previous infections. All IgM-negative samples showed high AIs. Patients with WNV neuroinvasive disease tested within 30 days showed low AIs. In six patients tested 34-50 days after disease onset, AI was borderline (42%-60%), suggesting earlier WNV IgG maturation. Samples with the highest IgM values were associated with the lowest AIs (Spearman's rho coefficient-0.767, p < 0.001). Conclusions: Our results indicate that IgG avidity differentiates current/recent WNV infection from persistent IgM seropositivity from the previous WNV transmission season both in patients with WNV neuroinvasive disease and in asymptomatic persons. A strong negative correlation between IgM antibody levels and AI indicates that in cases with very high IgM levels, determination of IgG avidity may not be necessary. As many patients showed rapid avidity maturation, low IgG avidity is indicative of WNV infection within the previous month.

Anti-SARS-CoV-2 IgG titer decreases rapidly after primovaccination, leading to a mandatory booster vaccination. We analysed anti-SARS-CoV-2 Spike RBD IgG levels (positive ≥ 50 AU/mL) in 405 healthcare workers (3010 sera) who received a booster dose (BD) 9 months after two-dose BNT162b2 primovaccination. Median antibody titer at the time of BD (582.6 AU/mL) was 1.7-fold and 16.4-fold lower than the peak titer after the first (961.5 AU/mL) and the second vaccine dose (SVD) (10,232.6 AU/mL), respectively. One month after vaccination, IgG titer increased 40.6-fold after BD compared with a 10.8-fold increase after primovaccination. Three months after vaccination, post-booster antibodies decreased significantly slower (2.2-fold) than after primovaccination (3.3-fold). At six months, antibodies decreased slower after BD (4.5-fold; median 5556.0 AU/mL) than after primovaccination (9.6-fold; median 1038.5 AU/mL). Antibody titers before and one month after BD correlated weakly (r = 0.30) compared with a strong correlation (r = 0.65) between the corresponding post-primovaccination titers. Pre-vaccination COVID-19 had no effect on IgG levels after BD compared with a positive effect after primovaccination. Despite high post-booster IgG levels, 22.5% of participants contracted mild COVID-19. The trend of IgG decline indicates the need for further revaccination, but the vaccine type should be defined according to viral mutations.

Genital warts (also known as condylomata acuminata) caused by the human papillomavirus (HPV) represent one of the most common sexually transmitted infections. Although they are usually found in the outer genital region, a small proportion of men can present with (often unrecognised) intraurethral warts, generally limited to the distal urethra and urethral meatus. This poses a treatment challenge not adequately addressed by the current guidelines. Here, we present two cases of low-risk HPV-positive patients with protruding and non-protruding condylomata acuminata of the distal urethra, which were treated successfully by using two different topical regimens (ie, a combination of policresulen and imiquimod for one patient and 5-fluorouracil monotherapy for the other). Although this type of management results in lower rates of tissue destruction and complications and may be given preference as an initial therapeutic option, additional prospective comparative clinical studies are needed to elucidate its potential in similar cases.

Purpose: Canine leishmaniosis is caused by Leishmania infantum, or also called in the New World L. chagasi. It is considered to be a major potentially fatal zoonotic infection where the domestic dog is the main reservoir. This infection is worldwide and reported with a higher incidence in tropical and subtropical areas such as South America where the number of infected dogs is estimated in the millions. No molecular data has been available on this disease in French Guiana. The aim of this study was molecular investigation of occurrence of leishmania in the blood of dogs in this region.Methods & Materials: Since 2016, blood samples were collected on a total of 98 dogs from French Guiana and 26 other dogs coming from continental France, were sampled before and after a 4-month mission in the same region. The samples were tested by a qPCR to quantify L. infantum kinetoplast DNA. Some positive samples were confirmed and species were identified, after sequencing, by using two standard PCR systems: i) a pan-Leishmania system was designed, targeting 28S rRNA gene and ii) PCR generic primers to amplify a segment of the rRNA internal transcribed spacer 2 (ITS2) from multiple Leishmania species.Results: The results show at least 4.08% (3/98) were positive to this pathogen and two (2/26) dogs returned positive although they were negative to begin with; one of them had an ulcer on the pastern. This last had 9 × 10 7 Leish/mL of blood, 1.3 × 10 10 Leish/mL from ulcer swab and around 4.3 × 10 6 Leish/g of bone marrow. In general, the parasite load was from 2.5 Leish/mL to 8 × 10 13 Leish/mL of dog's blood. Sequencing analyses identified L. infantum specie. Conclusion:The detection of L. infantum in local dogs in French Guiana and in dogs from metropolitan France after coming back from French Guiana, provide evidence that this region is endemic for canine leishmaniosis. It highlights the need for active surveillance in canine population and implementation of control measures. Competent vectors in this region are yet to be identified.