Humoral immune responses in hospitalized COVID-19 patients

Tracking the evolution of anti-SARS-CoV-2 antibodies and long-term humoral immunity within 2 years after COVID-19 infection

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that gave rise to COVID-19 infection produced a worldwide health crisis. The virus can cause a serious or even fatal disease. Comprehending the complex immunological responses triggered by SARS-CoV-2 infection is essential for identifying pivotal elements that shape the course of the disease and its enduring effects on immunity. The span and potency of antibody responses provide valuable perspicuity into the resilience of post-infection immunity. The analysis of existing literature reveals a diverse controversy, confining varying data about the persistence of particular antibodies as well as the multifaceted factors that impact their development and titer, Within this study we aimed to understand the dynamics of anti-SARS-CoV-2 antibodies against nucleocapsid (anti-SARS-CoV-2 (N)) and spike (anti-SARS-CoV-2 (N)) proteins in long-term immunity in convalescent patients, as well as the factors influencing the production and kinetics of those antibodies. We collected 6115 serum samples from 1611 convalescent patients at different post-infection intervals up to 21 months Study showed that in the fourth month, the anti-SARS-CoV-2 (N) exhibited their peak mean value, demonstrating a 79% increase compared to the initial month. Over the subsequent eight months, the peak value experienced a modest decline, maintaining a relatively elevated level by the end of study. Conversely, anti-SARS-CoV-2 (S) exhibited a consistent increase at each three-month interval over the 15-month period, culminating in a statistically significant peak mean value at the study's conclusion. Our findings demonstrate evidence of sustained seropositivity rates for both anti-SARS-CoV-2 (N) and (S), as well as distinct dynamics in the long-term antibody responses, with anti-SARS-CoV-2 (N) levels displaying remarkable persistence and anti-SARS-CoV-2 (S) antibodies exhibiting a progressive incline.

Declined Humoral Immunity of Kidney Transplant Recipients to SARS-CoV-2 Vaccines

Background

Kidney transplant recipients (KTRs) commonly suffer from impaired immunity. KTRs' compromised immune response to COVID-19 vaccines indicates urgent revision of immunisation policies.

Methods

A cross-sectional study was conducted in Madinah, Saudi Arabia of 84 KTRs who had received at least one dose of a COVID-19 vaccine. ELISA was used to evaluate anti-spike SARS-CoV-2 IgG and IgM antibody levels in blood samples obtained one month and seven months after vaccination. Univariate and multivariate analyses were performed to identify associations between seropositive status and factors such as the number of vaccine doses, transplant age, and immunosuppressive therapies.

Results

The mean age of KTRs was 44.3 ± 14.7 years. The IgG antibody seropositivity rate (n=66, 78.5%) was significantly higher than the seronegativity rate (n=18, 21.4%) in the whole cohort (p<0.001). In KTRs seroconverting after one month (n=66), anti-SARS-CoV-2 IgG levels declined significantly between one month (median [IQR]:3 [3-3]) and seven months (2.4 [1.7-2.6]) after vaccination (p<0.01). In KTRs with hypertension, IgG levels significantly decreased between one and seven months after vaccination (p<0.01). IgG levels also decreased significantly in KTRs with a transplant of >10 years (p=0.02). Maintenance immunosuppressive regimens (triple immunosuppressive therapy and steroid-based and antimetabolite-based regimens) led to a significant decrease in IgG levels between the first and second sample (p<0.01). KTRs receiving three vaccine doses showed higher antibody levels than those receiving a single dose or two doses, but the levels decreased significantly between one (median [IQR]: 3 [3-3]) and seven months (2.4 [1.9-2.6]) after vaccination (p<0.01).

Conclusion

KTRs' humoral response after SARS-CoV-2 vaccination is dramatically inhibited and wanes. Antibody levels show a significant decline over time in KTRs with hypertension; receiving triple immunosuppressive therapy or steroid-based or antimetabolite-based regimens; receiving mixed mRNA and viral vector vaccines; and with a transplant of >10 years.

Unexpected Detection of Anti-SARS-CoV-2 Antibodies Before the Declaration of the COVID-19 Pandemic

Background:

Limited information is currently available regarding the global incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections prior to the declaration of the coronavirus disease 2019 (COVID-19) pandemic, which may result in improper conclusions regarding the timing of viral transmission.

Methods

We investigated the presence of specific antibodies against the receptor-binding domain (RBD) of SARS-CoV-2 in archived serum samples that were collected from 478 healthy blood donors and patients in Madinah, Saudi Arabia, between October 2019 and January 2020. Enzyme-linked immunosorbent assay (ELISA) was performed to measure SARS-CoV-2 IgM and IgG antibodies. In addition, rheumatoid factor (RF) and urea dissociation tests were performed in all samples, which showed seropositivity for the SARS-CoV-2 IgM antibody. Additionally, Chemiluminescence immunoassays (CLIA) targeting the RBD of the SARS-CoV-2 spike (S) protein were performed to confirm the seropositivity of the samples.

Results

Overall, 20 (4.18%) serum samples were detected by ELISA to have SARS-CoV-2 IgG or IgM antibodies. Of these, 12 (2.51%) samples were positive for IgM antibody, and 8 (1.67%) were positive for IgG antibody. The 12 samples positive for SARS-CoV-2 IgM antibody were subjected to RF and urea dissociation tests, and all samples were RF-negative. The ELISA results were negative for 7 (58.33%) samples when subjected to urea dissociation prior to ELISA, whereas the other 5 (41.67%) samples remained positive. These 5 samples remained positive for the anti-S RBD IgG antibody in the CLIA. In addition, 3 of the 8 samples with IgG positivity according to the ELISA remained positive in the CLIA. After reviewing their data, we discovered that the 8 CLIA-confirmed positive samples were obtained from returned travellers who had visited China during the 4-week period immediately preceding blood donation.

Conclusion

In conclusion, we found evidence to support the early circulation of SARS-CoV-2 among persons who visited China a few months prior to the pandemic declaration. These results can be used to better define the spread of SARS-CoV-2 infections before the COVID-19 pandemic declaration. The detection of SARS-CoV-2 antibodies in individuals before the pandemic was declared in China could rewrite the pre-pandemic timeline.

A Single Dose of SARS-CoV-2 Vaccine Primes a Strong Humoral Immune Response in COVID-19-Recovered Patients

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causes coronavirus disease 2019 (COVID-19), which has affected hundreds of millions of people globally. The development of safe and effective vaccines represents an urgent demand. A total of 136 participants were recruited in this study, including 75 men and 61 women. The participants were divided into two groups: those who were virus naïve (never infected) and those who had recovered from COVID-19. Each group included individuals who received either the Pfizer-BioNTech BNT162b2 mRNA or the Oxford-AstraZeneca ChAdOx1 COVID-19 vaccine. Enzyme-linked immunosorbent assay (ELISA) was used to measure anti-S IgG antibody concentrations in sequential serum samples obtained before vaccine administration, after the first vaccine dose, and after the second vaccine dose. We compared the antibody responses of individuals with confirmed prior COVID-19 infection with those of individuals without prior evidence of infection. All participants who were previously infected with SARS-CoV-2 who received one dose of either the Pfizer-BioNTech BNT162b2 mRNA or the Oxford-AstraZeneca ChAdOx1 COVID-19 vaccine showed significant anti-S IgG antibody levels. No sex-related differences were observed when we compared antibody levels between men and women. In infection-naïve participants ≥60 years, a second vaccine dose was necessary to achieve higher levels of antibody when comparing the IgG antibody levels after receiving the first and second dose.