The COVID-19 pandemic necessitates better understanding of the kinetics of antibody production induced by infection with SARS-CoV-2. We aimed to develop a high-throughput multiplex assay to detect ...antibodies to SARS-CoV-2 to assess immunity to the virus in the general population.
Spike protein subunits S1 and receptor binding domain, and nucleoprotein were coupled to microspheres. Sera collected before emergence of SARS-CoV-2 (n = 224) and of non-SARS-CoV-2 influenza-like illness (n = 184), and laboratory-confirmed cases of SARS-CoV-2 infection (n = 115) with various severities of COVID-19 were tested for SARS-CoV-2-specific IgG concentrations.
Our assay discriminated SARS-CoV-2-induced antibodies and those induced by other viruses. The assay specificity was 95.1%-99.0% with sensitivity 83.6%-95.7%. By merging the test results for all 3 antigens a specificity of 100% was achieved with a sensitivity of at least 90%. Hospitalized COVID-19 patients developed higher IgG concentrations and the rate of IgG production increased faster compared to nonhospitalized cases.
The bead-based serological assay for quantitation of SARS-CoV-2-specific antibodies proved to be robust and can be conducted in many laboratories. We demonstrated that testing of antibodies against multiple antigens increases sensitivity and specificity compared to single-antigen-specific IgG determination.
mRNA- and vector-based vaccines are used at a large scale to prevent COVID-19. We compared Spike S1-specific (S1) IgG antibodies after vaccination with mRNA-based (Comirnaty, Spikevax) or ...vector-based (Janssen, Vaxzevria) vaccines, using samples from a Dutch nationwide cohort. In adults 18-64 years old (n = 2412), the median vaccination interval between the two doses was 77 days for Vaxzevria (interquartile range, IQR: 69-77), 35 days (28-35) for Comirnaty and 33 days (28-35) for Spikevax. mRNA vaccines induced faster inclines and higher S1 antibodies compared to vector-based vaccines. For all vaccines, one dose resulted in boosting of S1 antibodies in adults with a history of SARS-CoV-2 infection. For Comirnaty, two to four months following the second dose (n = 196), S1 antibodies in adults aged 18-64 years old (436 BAU/mL, IQR: 328-891) were less variable and median concentrations higher compared to those in persons ≥ 80 years old (366, 177-743), but differences were not statistically significant (p > 0.100). Nearly all participants seroconverted following COVID-19 vaccination, including the aging population. These data confirm results from controlled vaccine trials in a general population, including vulnerable groups.
Vaccine-induced protection against severe COVID-19, hospitalization, and death is of the utmost importance, especially in the elderly. However, limited data are available on humoral immune responses ...following COVID-19 vaccination in the general population across a broad age range. We performed an integrated analysis of the effect of age, sex, and prior SARS-CoV-2 infection on Spike S1-specific (S1) IgG concentrations up to three months post-BNT162b2 (Pfizer/BioNTech; Comirnaty) vaccination. In total, 1735 persons, eligible for COVID-19 vaccination through the national program, were recruited from the general population (12 to 92 years old). Sixty percent were female, and the median vaccination interval was 35 days (interquartile range, IQR: 35−35). All participants had seroconverted to S1 one month after two vaccine doses. S1 IgG was higher in participants with a history of SARS-CoV-2 infection (median: 4535 BAU/mL, IQR: 2341−7205) compared to infection-naive persons (1842 BAU/mL, 1019−3116), p < 0.001. In infection-naive persons, linear mixed effects regression showed a strong negative association between age and S1 IgG (p < 0.001) across the entire age range. Females had higher S1 IgG than males (p < 0.001). In persons with an infection history, age nor sex was associated with S1 IgG concentrations. The lower magnitude of S1 antibodies in older persons following COVID-19 vaccination will affect long-term protection.
With COVID-19 vaccine roll-out ongoing in many countries globally, monitoring of breakthrough infections is of great importance. Antibodies persist in the blood after a severe acute respiratory ...syndrome coronavirus 2 (SARS-CoV-2) infection. Since COVID-19 vaccines induce immune response to the Spike protein of the virus, which is the main serosurveillance target to date, alternative targets should be explored to distinguish infection from vaccination.
Multiplex immunoassay data from 1,513 SARS-CoV-2 RT-qPCR-tested individuals (352 positive and 1,161 negative) without COVID-19 vaccination history were used to determine the accuracy of Nucleoprotein-specific immunoglobulin G (IgG) in detecting past SARS-CoV-2 infection. We also described Spike S1 and Nucleoprotein-specific IgG responses in 230 COVID-19 vaccinated individuals (Pfizer/BioNTech).
The sensitivity of Nucleoprotein seropositivity was 85% (95% confidence interval: 80–90%) for mild COVID-19 in the first two months following symptom onset. Sensitivity was lower in asymptomatic individuals (67%, 50–81%). Participants who had experienced a SARS-CoV-2 infection up to 11 months preceding vaccination, as assessed by Spike S1 seropositivity or RT-qPCR, produced 2.7-fold higher median levels of IgG to Spike S1 ≥ 14 days after the first dose as compared to those unexposed to SARS-CoV-2 at ≥ 7 days after the second dose (p = 0.011). Nucleoprotein-specific IgG concentrations were not affected by vaccination in infection-naïve participants.
Serological responses to Nucleoprotein may prove helpful in identifying SARS-CoV-2 infections after vaccination. Furthermore, it can help interpret IgG to Spike S1 after COVID-19 vaccination as particularly high responses shortly after vaccination could be explained by prior exposure history.
Maternal antibody levels after Tdap vaccination during pregnancy may affect infant primary antibody responses to pertussis, Tetanus toxoid (TT), Diphtheria toxoid (DT) vaccinations and pneumococcal ...vaccines with diphtheria toxin mutants like CRM197 as carrier protein.
Mothers were recruited in an open label randomised parallel controlled trial in 2014–2016 through midwifes. They received Tdap Boostrix at 30–32 weeks of pregnancy (n = 58) or within 48 h after delivery (n = 60). Infants received DTaP-IPV-Hib-HepB Infanrix Hexa and 10-valent protein D conjugated pneumococcal conjugate vaccine (PHiD-CV10 Synflorix) at age 3, 5 and 11 months. We now report on infant specific IgG levels towards DT, TT, Haemophilus influenzae type b polyribosylribitol phosphate (Hib PRP) and PHiD-CV10 before and after primary- and booster vaccination as secondary study endpoints; pertussis antibodies were the primary endpoint of the study. This trial is registered in clinicaltrialsregister.eu (EudraCT 2012–004006-9) and trialregister.nl (NTR number NTR4314).
Post primary vaccinations, antibody levels to DT, but not TT, were significantly lower after Tdap vaccination during pregnancy compared to controls (GMC ratio 0.4, 95% CI 0.3–0.6 and 0.9, 95% CI 0.6–1.2, respectively). Antibodies to serotype 19F were significantly lower in the maternal Tdap group, whereas there were no differences in antibody levels to Hib PRP and the other 9 pneumococcal serotypes. Post booster vaccinations, no significant differences were observed, except for DT.
Maternal Tdap vaccination results in significant interference with infants responses not only to DT but also to conjugated pneumococcal vaccines containing DT mutants as carrier proteins. These interactions after maternal Tdap vaccination need to be taken into account when designing infants’ national immunization schedules and choice of vaccines.
The Dutch Ministry of Health, Welfare and Sport.
The aim of this study was to assess the safety and immunogenicity of a dose-sparing fractional intradermal (ID) booster strategy with the mRNA-1273 COVID-19 vaccine.
COVID-19 naive adults aged ...18–30 years were recruited from a previous study on primary vaccination regimens that compared 20 μg ID vaccinations with 100 μg intramuscular (IM) vaccinations with mRNA-1273 as the primary vaccination series. Participants previously immunized with ID regimens were randomly assigned (1:1) to receive a fractional ID booster dose (20 μg) or the standard-of-care intramuscular (IM) booster dose (50 μg) of the mRNA-1273 vaccine, 6 months after completing their primary series (ID-ID and ID-IM group, respectively). Participants that had received a full dose IM regimen as the primary series, received the IM standard-of-care booster dose (IM-IM group). In addition, COVID-19 naive individuals aged 18–40 years who had received an IM mRNA vaccine as the primary series were recruited from the general population to receive a fractional ID booster dose (IM-ID group). Immunogenicity was assessed using IgG anti-spike antibody responses and neutralizing capacity against SARS-CoV-2. Cellular immune responses were measured in a sub-group. Safety and tolerability were monitored.
In January 2022, 129 participants were included in the study. Fractional ID boosting was safe and well tolerated, with fewer systemic adverse events compared with IM boosting. At day 28 post-booster, anti-spike S1 IgG geometric mean concentrations were 9106 (95% CI, 7150–11 597) binding antibody units (BAU)/mL in the IM-IM group and 4357 (3003–6322) BAU/mL; 6629 (4913–8946) BAU/mL; and 5264 (4032–6873) BAU/mL in the ID-IM, ID-ID, and IM-ID groups, respectively.
Intradermal boosting provides robust immune responses and is a viable dose-sparing strategy for mRNA COVID-19 vaccines. The favourable side-effect profile supports its potential to reduce vaccine hesitancy. Fractional dosing strategies should be considered early in the clinical development of future mRNA vaccines to enhance vaccine availability and pandemic preparedness.
•The majority of the Dutch population (1–90 years of age) has parenteral and Omicron SARS-CoV-2–specific mucosal immunoglobulin (Ig)G antibodies.•The presence of SARS-CoV-2–specific IgA is largely ...dependent on a history of infection, whereas vaccination resulted in mucosal IgG.•Mucosal antibodies inhibit the binding of SARS-CoV-2 to human angiotensin-converting enzyme 2.•Increased levels of SARS-CoV-2–specific mucosal antibodies associate with a reduced risk of future infection.
Antibodies to SARS-CoV-2 on the mucosal surfaces of the respiratory tract are understood to contribute to protection against SARS-CoV-2 infection. We aimed to describe the prevalence, levels, and functionality of mucosal antibodies in the general Dutch population. Nasal samples were collected from 778 randomly selected participants, 1–90 years of age, nested within the nationwide prospective SARS-CoV-2 PIENTER corona serosurvey in the Netherlands. Spike-specific immunoglobulin (Ig)G was detected in the nasal samples of 94.6% (in case of the wild-type S1 variant) and 94.9% (Omicron BA.1) of the individuals, whereas 44.2% and 62.7% of the individuals were positive for wild-type and Omicron BA.1 S1 IgA, respectively. The lowest prevalence of mucosal antibodies was observed in children under 12 years of age. The prevalence and levels of IgA and IgG were higher in individuals with a history of SARS-CoV-2 infection. Mucosal antibodies inhibited the binding of Wuhan, Delta, and Omicron BA.1 receptor binding domain to human angiotensin-converting enzyme 2 in 94.4%, 95.4%, and 92.6% of the participants, respectively. Higher levels of mucosal antibodies were associated with a lower risk of future infection.
ABSTRACT
Background
To inform future response planning we aimed to assess SARS‐CoV‐2 trends in infection‐ and/or vaccine‐induced immunity, including breakthrough infections, among (sub)groups, ...professions and regions in the Dutch population during the Variant of Concern (VOC)‐era.
Methods
In this prospective population‐based cohort, randomly selected participants (n = 9985) aged 1–92 years (recruited early‐2020) donated home‐collected fingerstick‐blood samples at six timepoints in 2021/2022, covering waves dominated by Alpha, Delta, and multiple Omicron (sub‐)variants. IgG antibody assessment against Spike‐S1 and Nucleoprotein was combined with vaccination‐ and testing data to estimate infection‐induced (inf) and total (infection‐ and vaccination‐induced) seroprevalence.
Results
Nationwide inf‐seroprevalence rose modestly from 12% (95% CI 11–13) since Alpha to 26% (95% CI 24–28) amidst Delta, while total seroprevalence increased rapidly to 87% (95% CI 85–88), particularly in elderly and those with comorbidities (i.e., vulnerable groups). Interestingly, highest infection rates were noticeable among low/middle educated elderly, non‐Western, those in contact professions, adolescents and young adults, and in low‐vaccination coverage regions. Following Omicron emergence, inf‐seroprevalence elevated sharply to 62% (95% CI 59–65) and further to 86% (95% CI 83–90) in late‐2022, with frequent breakthrough infections and decreasing seroprevalence dissimilarities between most groups. Whereas > 90% of < 60‐year‐olds had been infected at least once, 30% of vaccinated vulnerable individuals had still not acquired hybrid immunity.
Conclusions
Groups identified to have been infected disproportionally during the acute phase of the pandemic require specific attention in evaluation of control measures and future response planning worldwide. Furthermore, ongoing tailored vaccination efforts and (sero‐)monitoring of vulnerable groups may remain important.
PDF
