COVID-19 antibody detection and assay performance using red cell agglutination

Red cells can be labelled with peptides from the SARS-CoV-2 spike protein and used for serologic screening of SARS-CoV-2 antibodies. We evaluated 140 convalescent COVID-19 patients and 275 healthy controls using this C19-kodecyte assay. The analytical performance of the new assay was compared with a virus neutralizing assay and 2 commercial chemiluminescent antibody tests (Total assay and IgG assay, Ortho). The C19-kodecyte assay detected SARS-CoV-2 antibodies with a sensitivity of 92.8% and specificity of 96.3%, well within the minimum performance range required by FDA for EUA authorization of serologic tests. The Cohen's kappa coefficient was 0.90 indicating an almost perfect agreement with the Total assay. The Pearson correlation coefficient was 0.20 with the neutralizing assay (0.49 with IgG, and 0.41 with Total assays). The limited correlation in assay reaction strengths suggested that the assays may detect different antibody specificities. Our easily scalable C19-kodecyte assay may vastly improve test capacity in blood typing laboratories using their routine setups for column agglutination technique.

Serologic Screening and Infectious Diseases Consultation in Renal Transplant Candidates for Measles, Mumps, Rubella and Varicella

Background: Renal transplant recipients are at increased risk for developing complications of vaccine-preventable diseases. They benefit from a comprehensive pre-transplant evaluation when they might safely receive live vaccines. The primary aim of our study was to investigate the number of renal transplant recipients who were evaluated for serologic status against measles, mumps, rubella (MMR), and varicella. Secondarily, we investigated if pre-transplant Infectious Diseases consultation (IDC) improved vaccination rates.Methods: We retrospectively analyzed 282 kidney-alone and kidney-plus adult transplant recipients who were born in or after 1957. Patients were evaluated at Mayo Clinic, Florida Transplant Center between January 2015 and December 2017. Serologic status evaluation and vaccination rates were compared in two groups created based on IDC and no ID consultation (NIDC).Results: 235 (83%) of a total 282 patients received an IDC pre-transplantation. Varicella IgG levels were screened in all 235 IDC candidates. Among the IDC patients, mumps, measles and rubella IgG serologies were performed in 7 (3%), 143 (61%) and 144 (61%), respectively. Among 44 patients seronegative for any of MMR, 24 (55%) were vaccinated. Ten (66%) of 15 varicella seronegative patients were vaccinated. Zostavax was not given to 18% of IDC patients. Zostavax and MMR were administered more frequently in the IDC group compared to NIDC (p<.001 and p=0.0016, respectively).Conclusion: Although the majority of patients had IDC, the screening rate for MMR serologies was lower than varicella. A protocol-driven serologic screening similar to the one for VZV is required for MMR. Pre-transplant IDC increases vaccination rates.

Prevention of perinatal hepatitis B virus transmission: are we missing something?

Background The prevention of perinatal Hepatitis B virus (HBV) is crucial to reach the WHO's challenge to eliminate viral hepatitis as public health threat by 2030. After diagnosing 2 infants infected by vertical transmission, a retrospective analysis of policies and practices to prevent HBV congenital infection was conducted to assess any potential risk. Methods Paired maternal-infant medical records between 2017 and 2019 were reviewed at A.O.U Città della Salute e Scienza di Torino, the italian hospital with the highest number of deliveries. Data included maternal HBSAg and coinfection (HIV, HCV) status and the administration of prophylaxis in newborns at risk. Other serologic markers of HBV maternal infection were not available. Results 132 (0,6%) newborns from HBsAg positive mothers were identified between 2017-2019 among 21143 newborns. In this group pre-natal HBSAg status was known in 127 (96,2%), the remaining were tested during the hospitalization. Regarding maternal coinfection 130 (98%) were tested for HIV (1 positive), only 60 (45.1%) for HCV (all negative). All newborns received immunoprophylaxis consisting in the administration of vaccination and immunoglobulin: 119 (89%) within 24 hours (63% within 12 hours), 12 (9%) between 24-36 hours and 2 (1,6%) after 36 hours. The 2 cases of vertical transmission, even if correctly vaccinated, show a vaccination failure of 1,5%. Conclusions Although most of the mothers were tested for HBSAg status and all newborns were given immunoprophylaxis, vaccination failure seems to explain the 2 cases of vertical transmission. Since the lack in early maternal serologic screening and the late vaccination time could increase the risk of HBV infection, to achieve WHO goal we suggest to implement a multidisciplinary pathway to identify HBV positive mothers, to treat in case of high viral load, to provide a timely immunoprophylaxis considering a early vaccination and to set up a structured postnatal serologic check for newborns at risk. Key messages Vaccination failure must be considered in the service organization, a structured postnatal serologic check for all newborns at risk should be implemented to detect potential vaccination failure. A multidisciplinary pathway to identify HBV positive mothers, with a full serological markers set, should be implemented to give a correct maternal therapy and newborn prophylaxis.