Understanding the dynamics of IgM & IgG antibodies in COVID-19-positive patients.

Background & objectives: The pandemic caused by the SARS-CoV-2 has been a threat to humankind due to the rapid spread of infection and appearance of multiple new variants. In the present study, we report the dynamics and persistence of immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies in asymptomatic and symptomatic COVID-19 patients by chemiluminescent assay. Methods: A total of 463 serum samples from 218 SARS-CoV-2 PCR-positive patients were collected over a period of 124 days post-onset of disease (POD). Antibody levels were measured by chemiluminescence bioanalyzer. Neutralizing antibody titres were assessed by plaque reduction neutralization test (PRNT) for SARS-CoV-2. Results: Both IgM and IgG started appearing from day five post-infection in symptomatic and asymptomatic patients. IgM antibody response peaked around day 35 POD and rapidly diminished thereafter, with the last IgM-positive sample observed at 90 days POD. IgG antibody response peaked around 45 days POD and persisted till 124 days. The chemiluminescence immunoassay (CLIA) results showed a moderate correlation (R=0.5846, P<0.001) compared with PRNT. Additional analysis indicated a neutralizing titre of 250 corresponded to 12.948 AU/ml of YHLO iFlash SARS-CoV-2 IgG units. Interpretation & conclusions: Both symptomatic and asymptomatic COVID-19 patients seem to initiate production of antibody responses from day five of onset of disease. Although the CLIA gives high sensitivity and specificity and also its binding IgG antibody titres may correlate moderately with protective immunity, our results indicate that the values of binding antibody alone may not be a perfect guide to represent virus neutralization titre during donor selection for plasma therapy. However, IgM and IgG antibody detection may help in monitoring the status of disease progression and burden in the community.

Longitudinal clinico-serological analysis of anti-nucleocapsid and anti-receptor binding domain of spike protein antibodies against SARS-CoV-2.

OBJECTIVES: Monitoring the antibody responses to SARS-CoV-2 infection and its correlation to clinical spectrum of disease is critical in understanding the disease progression and protection against re-infection. We assessed the nucleocapsid (N) and receptor-binding-domain of spike (SRBD) protein specific IgG and neutralizing antibody (NAb) responses in COVID-19 patients up to 8 months and its correlation with diverse disease spectrum. METHODS: During the first wave of the SARS-CoV-2 pandemic, from 284 COVID-19 patients, 608 samples were collected up to 8 months post infection. The patients were categorized as asymptomatic, symptomatic and severe. The N and SRBD IgG and NAb titers were evaluated and correlated with clinical data. RESULTS: A steep increase in antigen specific antibody titers was observed till 40 days post onset of the disease (POD), followed by a partial decline till 240 days. Severe disease was associated with a stronger SRBD IgG response and higher NAb titers. The persistence of antibody response was observed in 76% against N, 80% against SRBD and 80% for NAbs of cases up to 8 months POD. CONCLUSION: RBD and N protein specific IgG persisted till 240 days POD which correlated with NAb response, irrespective of individual`s symptomatic status indicating overall robust protection against re-infection.

Unusual Spurts of Rosacea Like Dermatoses, Posing a Diagnostic Dilemma During Covid-19 Pandemic: A Cross-Sectional, Observational Study From a Tertiary Care Centre.

BACKGROUND: The gradual opening of healthcare system since second week of May 2020 following lockdown imposed due to corona virus pandemic saw spurts of cases of unexplained central facial dermatoses in subset of previously healthy people. The aim of the study was to find out the cause and establish the definitive diagnosis of unusual occurrence of facial dermatoses on previously healthy people so that an appropriate management can be offered to the patients. MATERIALS AND METHODS: It was a cross-sectional, observational study carried during May 15 to July 15, 2020 at a tertiary dermatology center. All cases presented with erythema on face and papular or pustular lesions on central facial area of not more than 2 months of duration were included in the study. RESULTS: Total 81 patients visited skin OPD with facial dermatoses of various types during this period, out of which 21 patients fulfilled the inclusion criteria. This was 0.72% (21/2900) of total skin OPD of the 2 months. All the patients had been using face masks during this period of symptoms due to the ongoing coronavirus situation. Dermatological examination revealed only erythema on the central area of face (n = 10), erythema and few papules (n = 3), erythmatous papules and pustules (n = 5), and erythematous papules, pustules, and telengiectasia (n = 3). All the skin biopsies showed predominantly epithelioid cells, noncaseating granuloma with a variable degree of infiltrate. CONCLUSION: There has been a definite change in the lifestyle due to the current Covid-19 pandemic. People are compulsorily using face masks to avoid the spread of Covid-19 infection. This change in behavior has brought out a surge of rosacea like lesions on the covered area of face. Partly, it can be explained by change in innate immunity due to excessive sweating and change in microenvironment of skin.

Leukocytoclastic vasculitis as a cutaneous manifestation of ChAdOx1 nCoV-19 corona virus vaccine (recombinant).

With the present COVID-19 vaccination drive across the world, adverse skin reactions post COVID-19 vaccine is expected. Majority of these reactions seen were transient or local injection site reactions. However, as the larger population is being vaccinated, certain uncommon dermatological presentations including leukocytoclastic vasculitis, pityriasis rosea, and exacerbation of pre-existing autoimmune diseases are now being reported. Among all the COVID-19 vaccines, most of these reactions are seen with messenger ribonucleic acid-based Pfizer/BioNTech (BNT162b2) and Moderna (mRNA-1273) vaccine. We report two cases of leukocytoclastic vasculitis following ChAdOx1 nCoV-19 corona virus vaccine (recombinant) that bring out potential new dermatological manifestations of recombinant corona virus vaccine being administered across the European, South American, and Asian countries. It is important for all health care workers and patients to be aware of the corona virus vaccine associated adverse cutaneous reactions.