6-month SARS-CoV-2 antibody persistency in a Tyrolian COVID-19 cohort

A comprehensive review on immunogen and immune-response proteins of SARS-CoV-2 and their applications in prevention, diagnosis, and treatment of COVID-19

Exposure to severe acute respiratory syndrome-corona virus-2 (SARS-CoV-2) prompts humoral immune responses in the human body. As the auxiliary diagnosis of a current infection, the existence of viral proteins can be checked from specific antibodies (Abs) induced by immunogenic viral proteins. For people with a weakened immune system, Ab treatment can help neutralize viral antigens to resist and treat the disease. On the other hand, highly immunogenic viral proteins can serve as effective markers for detecting prior infections. Additionally, the identification of viral particles or the presence of antibodies may help establish an immune defense against the virus. These immunogenic proteins rather than SARS-CoV-2 can be given to uninfected people as a vaccination to improve their coping ability against COVID-19 through the generation of memory plasma cells. In this work, we review immunogenic and immune-response proteins derived from SARS-CoV-2 with regard to their classification, origin, and diverse applications (e.g., prevention (vaccine development), diagnostic testing, and treatment (via neutralizing Abs)). Finally, advanced immunization strategies against COVID-19 are discussed along with the contemporary circumstances and future challenges.

SARS-CoV-2 antibodies persist up to 12 months after natural infection in healthy employees working in non-medical contact-intensive professions

OBJECTIVES

This study aimed to evaluate dynamics of antibody levels after exposure to SARS-CoV-2 for 12 months in Dutch non-vaccinated hairdressers and hospitality staff.

METHODS

In this prospective cohort study, blood samples were collected every 3 months for 1 year and analyzed using a qualitative total antibody enzyme-linked immunosorbent assay (ELISA) and a quantitative immunoglobulin (Ig)G antibody ELISA. Participants completed questionnaires, providing information on demographics, health, and work. Differences in antibody levels were evaluated using Mann-Whitney U and Wilcoxon signed-rank tests. Beta coefficients (β) and 95% confidence intervals (CIs) were calculated using linear regression.

RESULTS

Ninety-five of 497 participants (19.1%) had ≥1 seropositive measurement before their last visit using the qualitative ELISA. Only 2.1% (2/95) seroreverted during follow-up. Of 95 participants, 82 (86.3%) tested IgG seropositive in the quantitative ELISA too. IgG antibody levels significantly decreased in the first months (P <0.01) but remained detectable for up to 12 months in all participants. Older age (β, 10-years increment: 24.6, 95% CI: 5.7-43.5) and higher body mass index (β, 5kg/m² increment: 40.0, 95% CI: 2.9-77.2) were significantly associated with a higher peak of antibody levels.

CONCLUSION

In this cohort, SARS-CoV-2 antibodies persisted for up to 1 year after initial seropositivity, suggesting long-term natural immunity.

Investigation of turning points in the effectiveness of Covid-19 social distancing

Covid-19 is the first digitally documented pandemic in history, presenting a unique opportunity to learn how to best deal with similar crises in the future. In this study we have carried out a model-based evaluation of the effectiveness of social distancing, using Austria and Slovenia as examples. Whereas the majority of comparable studies have postulated a negative relationship between the stringency of social distancing (reduction in social contacts) and the scale of the epidemic, our model has suggested a varying relationship, with turning points at which the system changes its predominant regime from 'less social distancing-more cumulative deaths and infections' to 'less social distancing-fewer cumulative deaths and infections'. This relationship was found to persist in scenarios with distinct seasonal variation in transmission and limited national intensive care capabilities. In such situations, relaxing social distancing during low transmission seasons (spring and summer) was found to relieve pressure from high transmission seasons (fall and winter) thus reducing the total number of infections and fatalities. Strategies that take into account this relationship could be particularly beneficial in situations where long-term containment is not feasible.

The kinetics and predictors of anti-SARS-CoV-2 antibodies up to eight months after symptomatic COVID-19: a Czech cross-sectional study

The presence of neutralizing SARS‐CoV‐2‐specific antibodies indicates protection against (re)infection, however, the knowledge of their long‐term kinetics is limited. This study analyzed the presence of COVID‐19‐induced antibodies in unvaccinated healthcare workers (HCWs) over the period of 1–8 months post symptom onset (SO) and explored the determinants of persisting immunoglobulin (Ig) seropositivity. Six hundred sixty‐two HCWs were interviewed for anamnestic data and tested for IgG targeting the spike protein (S1 and S2) and IgM targeting the receptor‐binding domain. A Cox regression model was used to explore potential predictors of seropositivity with respect to the time lapse between SO and serology testing. 82.9% and 44.7% of HCWs demonstrated IgG and IgM seropositivity, respectively, with a mean interval of 83 days between SARS‐CoV‐2 detection and serology testing. On average, HCWs reported seven symptoms in the acute phase lasting 20 days. IgG seropositivity rates among HCWs decreased gradually to 80%, 50%, and 35% at 3, 6, and 8 months after SO, while IgM seropositivity fell rapidly to 60%, 15%, and 0% over the same time intervals. The number of symptoms was the only predictor of persisting IgG seropositivity (odds ratio [OR] 1.096, 95% confidence interval [CI] 1.003–1.199, p = 0.043) and symptom duration a predictor of IgM seropositivity (OR 1.011, 95% CI 1.004–1.017, p = 0.002). Infection‐induced anti‐SARS‐CoV‐2 IgG rates drop to a third in seropositive participants over the course of 8 months. Symptom count and duration in the acute phase of COVID‐19 are both relevant to the subsequent kinetics of antibody responses.

60% and 35% of subjects maintain IgG seropositivity 6‐ and 8‐month post COVID‐19.

Characteristics of the acute phase of COVID‐19 are relevant for antibody responses.

The number of symptoms of acute COVID‐19 predicts persisting IgG seropositivity.

Symptom duration predicts persisting IgM seropositivity.

Anamnestic data may serve as simple predictors of seropositivity post COVID‐19.

Humoral immune response after COVID-19 in multiple sclerosis: A nation-wide Austrian study

BACKGROUND

Knowledge on immunity after SARS-CoV-2 infection in patients with multiple sclerosis (pwMS) and the impact of disease-modifying treatment (DMT) is limited.

OBJECTIVE

To evaluate degree, duration and potential predictors of specific humoral immune response in pwMS with prior COVID-19.

METHODS

Anti-SARS-CoV-2 antibody testing was performed in pwMS with PCR-confirmed diagnosis of symptomatic COVID-19 from a nation-wide registry. Predictors of seropositivity were identified by multivariate regression models.

RESULTS

In 125 pwMS (mean age = 42.4 years (SD = 12.3 years), 70% female), anti-SARS-CoV-2 antibodies were detected in 76.0% after a median of 5.2 months from positive PCR. Seropositivity rate was significantly lower in patients on IS-DMT (61.4%, p = 0.001) than without DMT or immunomodulatory DMT (80.6%; 86.0%, respectively). In multivariate analysis, IS-DMT was associated with reduced probability of seropositivity (odds ratio (OR): 0.51; 95% confidence interval (95% CI): 0.17-0.82; p < 0.001). Predefined subgroup analyses showed marked reduction of seropositivity in pwMS on rituximab/ocrelizumab (OR 0.15; 95% CI: 0.05-0.56; p < 0.001). Rate of seropositivity did not change significantly over 6 months.

CONCLUSIONS

Humoral immunity is stable after SARS-CoV-2 infection in MS, but is reduced by immunosuppressive DMT, particularly anti-CD20 monoclonal antibodies. This provides important evidence for advising pwMS as well as for planning and prioritizing vaccination.

12-month SARS-CoV-2 antibody persistency in a Tyrolean COVID-19 cohort

Background

Short-term antibody response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been shown previously. The further development remains to be determined.

Methods

We prospectively followed 29 coronavirus disease 2019 cases, mean age 44 ± 13.2 years. Except for one participant in whom rheumatoid arthritis existed, all other cases were previously healthy. We determined anti-viral binding antibodies at 2–10 weeks, 3 months, 6 months, and 12 months after disease onset as well as neutralizing antibodies (NAb) against wild type at 6 and 12 months and the B.1.1.7 and B.1.351 variants at month 12. Three binding antibody assays were used, targeting the nucleocapsid protein (NCP), the S1 subunit of the spike protein, and the receptor binding domain (RBD).

Results

Antibodies to the RBD persisted for 12 months in all cases with increasing concentrations, whereas antibodies to S1 dropped below cut-off point in 7 participants and NCP antibodies were above cut-off point in only 5 subjects at month 12. The NAb against wild type were detected in all but 2 samples at 12 months of follow-up but clearly less frequently when targeting the variants. In 5 participants who were vaccinated against COVID-19 there was a strong increase of antibodies against S1 and RBD as well as an increase of NAb titres against wild type and the variants.

Conclusion

There was a persisting antibody response against SARS-CoV‑2 up to 12 months after COVID-19 with declining concentrations except for RBD and a strong increase of all antibody concentrations after vaccination.

Supplementary Information

The online version of this article (10.1007/s00508-021-01985-x) contains supplementary material, which is available to authorized users.

Detection and predictors of anti-SARS-CoV-2 antibody levels in COVID-19 patients at 8 months after symptom onset

Aim: To determine SARS-CoV-2 specific IgM and IgG levels of patients with COVID-19 at 8 months after symptom onset and to explore the predictors of antibody levels. Materials & methods: The magnetic chemiluminescence method was used to measure the antibody levels. Clinical data were collected and analyzed retrospectively. Results: A total of 54 patients were enrolled in this study, of whom 59.3% were IgM positive and 96.4% were IgG positive. The multiple linear regression analysis revealed that the duration of RNA shedding, C-reactive protein level and disease severity were independent predictors of IgG levels. Conclusion: COVID-19 patients retained long-term viral-specific protective immunity. Disease severity, C-reactive protein level and duration of RNA shedding were related to antibody levels 8 months after symptom onset.

This study aimed to detect the levels of antibodies made by the body in response to COVID-19, 8 months after infection. We reviewed the characteristics of 54 patients with a history COVID-19 to find factors that may influence antibody levels. The results showed that 8 months after infection, almost all the patients had sufficient antibody levels to protect them from another episode of COVID-19 and that antibody levels were especially well maintained in those with a history of severe COVID-19.

Frequency, signs and symptoms, and criteria adopted for long COVID-19: A systematic review

AIMS

To identify, systematically evaluate and summarise the best available evidence on the frequency of long COVID-19 (post-acute COVID-19 syndrome), its clinical manifestations, and the criteria used for diagnosis.

METHODS

Systematic review conducted with a comprehensive search including formal databases, COVID-19 or SARS-CoV-2 data sources, grey literature, and manual search. We considered for inclusion clinical trials, observational longitudinal comparative and non-comparative studies, cross-sectional, before-and-after, and case series. We assessed the methodological quality by specific tools based on the study designs. We presented the results as a narrative synthesis regarding the frequency and duration of long COVID-19, signs and symptoms, criteria used for diagnosis, and potential risk factors.

RESULTS

We included 25 observational studies with moderate to high methodological quality, considering 5440 participants. The frequency of long COVID-19 ranged from 4.7% to 80%, and the most prevalent signs/symptoms were chest pain (up to 89%), fatigue (up to 65%), dyspnea (up to 61%), and cough and sputum production (up to 59%). Temporal criteria used to define long COVID-19 varied from 3 to 24 weeks after acute phase or hospital discharge. Potentially associated risk factors were old age, female sex, severe clinical status, a high number of comorbidities, hospital admission, and oxygen supplementation at the acute phase. However, limitations related to study designs added uncertainty to this finding. None of the studies assessed the duration of signs/symptoms.

CONCLUSION

The frequency of long COVID-19 reached up to 80% over the studies included and occurred between 3 and 24 weeks after acute phase or hospital discharge. Chest pain, fatigue, dyspnea, and cough were the most reported clinical manifestations attributed to the condition. Based on these systematic review findings, there is an urgent need to understand this emerging, complex and challenging medical condition. Proposals for diagnostic criteria and standard terminology are welcome.

Persistence of humoral response upon SARS-CoV-2 infection

SARS‐CoV‐2 continues to leave its toll on global health and the economy. Management of the pandemic will rely heavily on the degree of adaptive immunity persistence following natural SARS‐CoV‐2 infection. Along with the progression of the pandemic, more literature on the persistence of the SARS‐CoV‐2‐specific antibody response is becoming available. Here, we summarize findings on the persistence of the humoral, including neutralizing antibody, response at three to eight months post SARS‐CoV‐2 infection in non‐pregnant adults. While the comparability of the literature is limited, findings on the detectability of immunoglobulin G class of antibodies (IgG) were most consistent and were reported in most studies to last for six to eight months. Studies investigating the response of immunoglobins M and A (IgM, IgA) were limited and reported mixed results, in particular, for IgM. The majority of studies observed neutralizing antibodies at all time points tested, which in some studies lasted up to eight months. The presence of neutralizing antibodies has been linked to protection from re‐infection, suggesting long‐term immunity to SARS‐CoV‐2. These neutralizing capacities may be challenged by emerging virus variants, but mucosal antibodies as well as memory B and T cells may optimize future immune responses. Thus, further longitudinal investigation of PCR‐confirmed seropositive individuals using sensitive assays is warranted to elucidate the nature and duration of a more long‐term humoral response.

Passive Immunity Should and Will Work for COVID-19 for Some Patients

In the absence of effective antiviral chemotherapy and still in the context of emerging vaccines for severe acute respiratory syndrome-CoV-2 infections, passive immunotherapy remains a key treatment and possible prevention strategy. What might initially be conceived as a simplified donor-recipient process, the intricacies of donor plasma, IV immunoglobulins, and monoclonal antibody modality applications are becoming more apparent. Key targets of such treatment have largely focused on virus neutralization and the specific viral components of the attachment Spike protein and its constituents (e.g., receptor binding domain, N-terminal domain). The cumulative laboratory and clinical experience suggests that beneficial protective and treatment outcomes are possible. Both a dose- and a time-dependency emerge. Lesser understood are the concepts of bioavailability and distribution. Apart from direct antigen binding from protective immunoglobulins, antibody effector functions have potential roles in outcome. In attempting to mimic the natural but variable response to infection or vaccination, a strong functional polyclonal approach attracts the potential benefits of attacking antigen diversity, high antibody avidity, antibody persistence, and protection against escape viral mutation. The availability and ease of administration for any passive immunotherapy product must be considered in the current climate of need. There is never a perfect product, but yet there is considerable room for improving patient outcomes. Given the variability of human genetics, immunity, and disease, and given the nuances of the virus and its potential for change, passive immunotherapy can be developed that will be effective for some but not all patients. An understanding of such patient variability and limitations is just as important as the understanding of the direct interactions between immunotherapy and virus.