Humoral Immunity of Unvaccinated COVID-19 Recovered vs. Naïve BNT162b2 Vaccinated Individuals: A Prospective Longitudinal Study

Association between Mexican vaccination schemes and the duration of long COVID syndrome symptoms

The COVID-19 pandemic had a profound global impact, characterized by a high fatality rate and the emergence of enduring consequences known as Long COVID. Our study sought to gauge the prevalence of Long COVID syndrome in northeastern Mexico, correlating it with patients' comorbidities and vaccination records. We carried out an observational cross-sectional approach, by administering a comprehensive questionnaire covering patients' medical history, demographics, vaccination status, COVID-related symptoms, their duration, and any treatment received. Our participant cohort included 804 patients, averaging 41.5 (SD 13.6) years in age, with 59.3% being women. Notably, 168 individuals (20.9%) met Long COVID criteria. Our analysis of COVID-19 long lasting compared vaccination schemes, unveiling a significant difference between vaccinated and unvaccinated groups (p =  < 0.001). Through linear regression model, we found male gender (β = - 0.588, p < 0.001) and vaccination status (β = 0.221, p = 0.015) acted as protective factors against Long COVID symptom duration, while higher BMI was a risk factor (β = - 0.131, p = 0.026). We saw that the duration of Long COVID was different within vaccinated patients, and we did not find any association of comorbidities with an increase in the presence of symptoms. Even three years after the pandemic, a significant prevalence of Long COVID persists, and there is still a lack of standardized information and any possible treatment regarding this condition.

Avidity maturation of anti-spike IgG after vaccination in COVID-19 convalescent vs COVID-19 naïve patients

Antibodies and avidity maturation contribute to long-lasting immunity, and previous COVID-19 seems to enhance the immune response after vaccination. The aim of this study was to compare the immune response after vaccination between COVID-19 convalescents and naïve patients. Blood samples from COVID-19 convalescents and naïve patients, taken 1, 3 and 6 months after the second dose of vaccine (mRNA-vaccine BNT162b2), were analysed for anti-spike IgG and avidity. Questionnaires concerning side effects were used. Thirty-one patients in the COVID-19 cohort and 30 patients in the naïve cohort were included. High levels of anti-spike IgG and avidity index were seen. Anti-spike IgG were significantly higher in the COVID-19 cohort and declining (median 1250, 566, 282 RU/ml vs 565, 187, 65 RU/ml). Avidity did not change over time (median at 6 months 78% vs 65%). The most common side effects were pain at the injection site, malaise and headache. In conclusion, high levels of anti-spike IgG after vaccination were seen and most patients developed high-avidity antibodies, although antibody levels and avidity were higher in the COVID-19 cohort. Over time, the levels of anti-spike IgG declined, yet avidity remained high. Side effects did not differ between groups and were of short duration.

Immunoglobulins in COVID-19 pneumonia: from the acute phase to the recovery phase

BACKGROUND

COVID-19 pneumonia causes hyperinflammatory response that culminates in acute respiratory syndrome (ARDS) related to increased multiorgan dysfunction and mortality risk. Antiviral-neutralizing immunoglobulins production reflect the host humoral status and illness severity, and thus, immunoglobulin (Ig) circulating levels could be evidence of COVID-19 prognosis.

METHODS

The relationship among circulating immunoglobulins (IgA, IgG, IgM) and COVID-19 pneumonia was evaluated using clinical information and blood samples in a COVID-19 cohort composed by 320 individuals recruited during the acute phase and followed up to 4 to 8 weeks (n = 252) from the Spanish first to fourth waves.

RESULTS

COVID-19 pneumonia development depended on baseline Ig concentrations. Circulating IgA levels together with clinical features at acute phase was highly associated with COVID-19 pneumonia development. IgM was positively correlated with obesity (ρb = 0.156, P = 0.020), dyslipemia (ρb = 0.140, P = 0.029), COPD (ρb = 0.133, P = 0.037), cancer (ρb = 0.173, P = 0.007) and hypertension (ρb = 0.148, P = 0.020). Ig concentrations at recovery phase were related to COVID-19 treatments.

CONCLUSIONS

Our results provide valuable information on the dynamics of immunoglobulins upon SARS-CoV-2 infection or other similar viruses.