Waning Immunity 14 Months After SARS-CoV-2 Infection

SARS-CoV-2 antibody levels and long COVID occurrence in blood donors

BACKGROUND

Long COVID is a common condition lacking consensus definition; determinants remain incompletely understood. Characterizing immune profiles associated with long COVID could support the development of preventive and therapeutic strategies.

METHODS

We used a survey to investigate blood donors' infection/vaccination history and acute/persistent symptoms following COVID-19. The prevalence of long COVID was evaluated using self-report and an adapted definition from the RECOVER study. We evaluated factors associated with long COVID, focusing on anti-spike and anti-nucleocapsid SARS-CoV-2 antibodies. Lastly, we investigated long COVID clinical subphenotypes using hierarchical clustering.

RESULTS

Of 33,610 participants, 16,003 (48%) reported having had COVID-19; 1853 (12%) had self-reported long COVID, 685 (4%) met an adapted RECOVER definition, and 2050 (13%) met at least one definition. Higher anti-nucleocapsid levels measured 12-24 weeks post-infection were associated with higher risk of self-reported and RECOVER long COVID. Higher anti-spike IgG levels measured 12-24 weeks post-infection were associated with lower risk of self-reported long COVID. Higher total anti-spike measured 24-48 weeks post-infection was associated with lower risk of RECOVER long COVID. Cluster analysis identified four clinical subphenotypes; patterns included neurological and psychiatric for cluster 1; neurological and respiratory for cluster 2; multi-systemic for cluster 3; and neurological for cluster 4.

DISCUSSION

Long COVID prevalence in blood donors varies depending on the adopted definition. Anti-SARS-CoV-2 antibodies were time-dependently associated with long COVID; higher anti-nucleocapsid levels were associated with higher risk; and higher anti-spike levels were associated with lower risk of long COVID. Different underlying pathophysiologic mechanisms may be associated with distinct clinical subphenotypes.

SARS-CoV-2 Seroepidemiology and Antibody Levels in Children during BA.5 Predominance Period

This is a SARS-CoV-2 seroepidemiological study in a pediatric population (0-16 years) during the BA.5 Omicron predominance period in the Athens metropolitan area. Serum samples were tested for SARS-CoV-2 nucleocapsid antibodies (Abs-N), representing natural infection during three periods of BA.5 predominance: 1 May 2022-31 August 2022 (period A), 1 September 2022-31 December 2022 (period B), and July 2023 (period C). Εpidemiological data were also collected. Additionally, in period C, Abs-N-seronegative samples were tested for SARS-CoV-2 spike antibodies (Abs-S). A total of 878 children were tested (males: 52.6%), with a median age (IQR) of 96 (36-156) months; the number of cases of seropositivity during the three periods were as follows: A: 292/417 (70%), B: 288/356 (80.9%), and C: 89/105 (84.8%), with p < 0.001. SARS-CoV-2 seropositivity increased from period A to C for children 0-1 year (p = 0.044), >1-4 years (p = 0.028), and >6-12 years (p = 0.003). Children > 6-12 years had the highest seropositivity rates in all periods (A: 77.3%, B: 91.4%, and C: 95.8%). A significant correlation of monthly median Abs-N titers with monthly seropositivity rates was detected (rs: 0.812, p = 0.008). During period C, 12/105 (11.4%) Abs-S-seropositive and Abs-N-seronegative samples were detected and total seropositivity was estimated at 96.2% (101/105). The findings of this study indicate a high SARS-CoV-2 exposure rate of children during the BA.5 predominance period and suggest that in future seroepidemiological studies, both antibodies should be tested in Abs-N-seronegative populations.

Comparing SARS-CoV-2 variants among children and adolescents in Germany: relative risk of COVID-19-related hospitalization, ICU admission and mortality

PURPOSE

SARS-CoV-2 infections cause COVID-19 and have a wide spectrum of morbidity. Severe disease courses among children are rare. To date, data on the variability of morbidity in relation to variant of concern (VOC) in children has been sparse and inconclusive. We compare the clinical severity of SARS-CoV-2 infection among children and adolescents in Germany during the Wildtype and Alpha combined, Delta and Omicron phases of the COVID-19 pandemic.

METHODS

Comparing risk of COVID-19-related hospitalization, intensive care unit (ICU) admission and death due to COVID-19 in children and adolescents, we used: (1) a multi-center seroprevalence study (SARS-CoV-2-KIDS study); (2) a nationwide registry of pediatric patients hospitalized with SARS-CoV-2 infections; and (3) compulsory national reporting for RT-PCR-confirmed SARS-CoV-2 infections in Germany.

RESULTS

During the Delta predominant phase, risk of COVID-19-related hospitalization among all SARS-CoV-2 seropositive children was 3.35, ICU admission 1.19 and fatality 0.09 per 10,000; hence about halved for hospitalization and ICU admission and unchanged for deaths as compared to the Wildtype- and Alpha-dominant period. The relative risk for COVID-19-related hospitalization and ICU admission compared to the alpha period decreased during Delta [0.60 (95% CI 0.54; 0.67) and 0.51 (95% CI 0.42; 0.61)] and Omicron [0.27 (95% CI 0.24; 0.30) and 0.06 (95% CI 0.05; 0.08)] period except for the < 5-year-olds. The rate of case fatalities decreased slightly during Delta, and substantially during Omicron phase.

CONCLUSION

Morbidity caused by SARS-CoV-2 infections among children and adolescents in Germany decreased over the course of the COVID-19 pandemic, as different VOCs) emerged.

Precision Vaccinology Approaches for the Development of Adjuvanted Vaccines Targeted to Distinct Vulnerable Populations

Infection persists as one of the leading global causes of morbidity and mortality, with particular burden at the extremes of age and in populations who are immunocompromised or suffer chronic co-morbid diseases. By focusing discovery and innovation efforts to better understand the phenotypic and mechanistic differences in the immune systems of diverse vulnerable populations, emerging research in precision vaccine discovery and development has explored how to optimize immunizations across the lifespan. Here, we focus on two key elements of precision vaccinology, as applied to epidemic/pandemic response and preparedness, including (a) selecting robust combinations of adjuvants and antigens, and (b) coupling these platforms with appropriate formulation systems. In this context, several considerations exist, including the intended goals of immunization (e.g., achieving immunogenicity versus lessening transmission), reducing the likelihood of adverse reactogenicity, and optimizing the route of administration. Each of these considerations is accompanied by several key challenges. On-going innovation in precision vaccinology will expand and target the arsenal of vaccine components for protection of vulnerable populations.

Immune Response following BNT162b2 mRNA COVID-19 Vaccination in Pediatric Cancer Patients

COVID-19 vaccinations are recommended for children with cancer but data on their vaccination response is scarce. This study assesses the antibody and T-cell response following a 2- or 3-dose vaccination with BNT162b2 mRNA COVID-19 vaccine in children (5-17 years) with cancer. For the antibody response, participants with a serum concentration of anti-SARS-CoV-2 spike 1 antibodies of >300 binding antibody units per milliliter were classified as good responders. For the T-cell response, categorization was based on spike S1 specific interferon-gamma release with good responders having >200 milli-international units per milliliter. The patients were categorized as being treated with chemo/immunotherapy for less than 6 weeks (Tx < 6 weeks) or more than 6 weeks (Tx > 6 weeks) before the first immunization event. In 46 patients given a 2-dose vaccination series, the percentage of good antibody and good T-cell responders was 39.3% and 73.7% in patients with Tx < 6 weeks and 94.4% and 100% in patients with Tx > 6 weeks, respectively. An additional 3rd vaccination in 16 patients with Tx < 6 weeks, increased the percentage of good antibody responders to 70% with no change in T-cell response. A 3-dose vaccination series effectively boosted antibody levels and is of value for patients undergoing active cancer treatment.

COVID-19 Vaccines in Children

The coronavirus disease 2019 (COVID-19) pandemic has transformed the world. It has highlighted health inequities, the lack of social safety nets, and the limitations of health care systems. But it has also paved the way for medical ingenuity and technological advances in the face of these extreme challenges. One such medical marvel is the COVID-19 vaccine. The ability to rapidly create and mass produce a safe and effective vaccine for both adults and children has been essential to minimizing the harm of COVID-19, reducing the burden on hospitals and ushering in some semblance of return to pre-COVID times. Although vaccine hesitancy and long-standing health inequities have limited the number of children who have received the COVID-19 vaccine, the recommended vaccines remain a vital tool in ensuring healthy growth and development of children. [Pediatr Ann. 2023;52(1):e4-e7.].