Antibody response after one and two jabs of the BNT162b2 vaccine in nursing home residents: The CONsort-19 study.

The humoral immune response following COVID-19 vaccination in nursing home residents is poorly known. A longitudinal study compared levels of IgG antibodies against the spike protein (S-RBD IgG) (S-RDB protein IgG) after one and two BNT162b2/Pfizer jabs in residents with and without prior COVID-19. In 22 French nursing homes, COVID-19 was diagnosed with real-time reverse-transcriptase polymerase chain reaction (RT-PCR) for SARS-CoV-2. Blood S-RDB-protein IgG and nucleocapsid (N) IgG protein (N-protein IgG) were measured 21-24 days after the first jab (1,004 residents) and 6 weeks after the second (820 residents). In 735 residents without prior COVID-19, 41.7% remained seronegative for S-RDB-protein IgG after the first jab vs. 2.1% of the 270 RT-PCR-positive residents (p < 0.001). After the second jab, 3% of the 586 residents without prior COVID-19 remained seronegative. However, 26.5% had low S-RDB-protein IgG levels (50-1050 UA/ml) vs. 6.4% of the 222 residents with prior COVID-19. Residents with an older infection (first wave), or with N-protein IgG at the time of vaccination, had the highest S-RDB-protein IgG levels. Residents with a prior COVID-19 infection had higher S-RDB-protein IgG levels after one jab than those without after two jabs. A single vaccine jab is sufficient to reach a high humoral immune response in residents with prior COVID-19. Most residents without prior COVID-19 are seropositive for S-RDB-protein IgG after the second jab, but around 30% have low levels. Whether residents with no or low post-vaccine S-RDB protein IgG are at higher risk of symptomatic COVID-19 requires further analysis.

Blain H ，Tuaillon E ，Gamon L ，Pisoni A ，Miot S ，Rolland Y ，Picot MC ，Bousquet J ... -  《-》

Strong Decay of SARS-CoV-2 Spike Antibodies after 2 BNT162b2 Vaccine Doses and High Antibody Response to a Third Dose in Nursing Home Residents.

To measure the antibody decay after 2 BNT162b2 doses and the antibody response after a third vaccine dose administered 6 months after the second one in nursing home residents with and without prior COVID-19. Cohort study. Four hundred-eighteen residents from 18 nursing homes. Blood receptor-binding domain (RBD)-IgG (IgG II Quant assay, Abbott Diagnostics; upper limit: 5680 BAU) and nucleocapsid-IgG (Abbott Alinity) were measured 21‒28 days after the second BNT162b2 dose, as well as 1‒3 days before and 21‒28 days after the third vaccine dose. RBD-IgG levels of ≥592 BAU/mL were considered as high antibody response. Residents with prior positive quantitative reverse transcription polymerase chain reaction on a nasopharyngeal swab or with N-IgG levels above 0.8 S/CO were considered as prior COVID-19 residents. In prior COVID-19 residents (n = 122), RBD-IgG median levels decreased by 82% in 167 days on average. In the same period, the number of residents with a high antibody response decreased from 88.5% to 54.9% (P < .0001) and increased to 97.5% after the third vaccine dose (P = .02 vs the first measure). In residents without prior COVID-19 (n = 296), RBD-IgG median levels decreased by 89% in 171 days on average. The number of residents with a high antibody response decreased from 29.4% to 1.7% (P < .0001) and increased to 88.4% after the third vaccine dose (P < .0001 vs the first measure). The strong and rapid decay of RBD-IgG levels after the second BNT162b2 dose in all residents and the high antibody response after the third dose validate the recommendation of a third vaccine dose in residents less than 6 months after the second dose, prioritizing residents without prior COVID-19. The slope of RBD-IgG decay after the third BNT162b2 dose and the protection level against SARS-CoV-2 B.1.1.529 (omicron) and other variants of concern provided by the high post-boost vaccination RBD-IgG response require further investigation in residents.

Blain H ，Tuaillon E ，Gamon L ，Pisoni A ，Miot S ，Picot MC ... -  《-》

Receptor binding domain-IgG levels correlate with protection in residents facing SARS-CoV-2 B.1.1.7 outbreaks.

Limited information exists on nursing home (NH) residents regarding BNT162b2 vaccine efficacy in preventing SARS-CoV-2 and severe COVID-19, and its association with post-vaccine humoral response. 396 residents from seven NHs suffering a SARS-CoV-2 B.1.1.7 (VOC-α) outbreak at least 14 days after a vaccine campaign were repeatedly tested using SARS-CoV-2 real-time reverse-transcriptase polymerase chain reaction on nasopharyngeal swab test (RT-qPCR). SARS-CoV-2 receptor-binding domain (RBD) of the S1 subunit (RBD-IgG) was measured in all residents. Nucleocapsid antigenemia (N-Ag) was measured in RT-qPCR-positive residents and serum neutralizing antibodies in vaccinated residents from one NH. The incidence of positive RT-qPCR was lower in residents vaccinated by two doses (72/317; 22.7%) vs one dose (10/31; 32.3%) or non-vaccinated residents (21/48; 43.7%; p < .01). COVID-19-induced deaths were observed in 5 of the 48 non-vaccinated residents (10.4%), in 2 of the 31 who had received one dose (6.4%), and in 3 of the 317 (0.9%) who had received two doses (p = .0007). Severe symptoms were more common in infected non-vaccinated residents (10/21; 47.6%) than in infected vaccinated residents (15/72; 21.0%; p = .002). Higher levels of RBD-IgG (n = 325) were associated with a lower SARS-CoV-2 incidence. No in vitro serum neutralization activity was found for RBD-IgG levels below 1050 AU/ml. RBD-IgG levels were inversely associated with N-Ag levels, found as a risk factor of severe COVID-19. Two BNT162b2 doses are associated with a 48% reduction of SARS-CoV-2 incidence and a 91.3% reduction of death risk in residents from NHs facing a VOC-α outbreak. Post-vaccine RBD-IgG levels correlate with BNT162b2 protection against SARS-CoV-2 B.1.1.7.

Blain H ，Tuaillon E ，Gamon L ，Pisoni A ，Miot S ，Delpui V ，Si-Mohamed N ，Niel C ，Rolland Y ，Montes B ，Groc S ，Rafasse S ，Dupuy AM ，Gros N ，Muriaux D ，Picot MC ，Bousquet J ... -  《-》

Antibody response after first and second BNT162b2 vaccination to predict the need for subsequent injections in nursing home residents.

We explored antibody response after first and second BNT162b2 vaccinations, to predict the need for subsequent injections in nursing home (NH) residents. 369 NH residents were tested for IgG against SARS-CoV-2 Receptor-Binding Domain (RBD-IgG) and nucleoprotein-IgG (SARS-CoV-2 IgG II Quant and SARS-CoV-2 IgG Alinity assays, Abbott Diagnostics). In NH residents with prior SARS-CoV-2 infection, the first dose elicited high RBD-IgG levels (≥ 4160 AU/mL) in 99/129 cases (76.9%), with no additional antibody gain after the second dose in 74 cases (74.7%). However, a low RBD-IgG level (< 1050 AU/mL) was observed in 28 (21.7%) residents. The persistence of nucleoprotein-IgG and a longer interval between infection and the first dose were associated with a higher RBD-IgG response (p < 0.0001 and p = 0.0013, respectively). RBD-IgG below 50 AU/mL after the first dose predicted failure to reach the antibody concentration associated with a neutralizing effect after the second dose (≥ 1050 AU/mL). The BNT162b2 vaccine elicited a strong humoral response after the first dose in a majority of NH residents with prior SARS-CoV-2 infection. However, about one quarter of these residents require a second injection. Consideration should be given to immunological monitoring in NH residents to optimize the vaccine response in this vulnerable population.

Tuaillon E ，Pisoni A ，Veyrenche N ，Rafasse S ，Niel C ，Gros N ，Muriaux D ，Picot MC ，Aouinti S ，Van de Perre P ，Bousquet J ，Blain H ... -  《Scientific Reports》

Pronounced antibody elevation after SARS-CoV-2 BNT162b2 mRNA booster vaccination in nursing home residents.

Infection control during COVID-19 outbreaks in nursing facilities is a critical public health issue. Antibody responses before and after the third (booster) dose of SARS-CoV-2 vaccination in nursing home residents have not been fully characterized. This study included 117 individuals: 54 nursing home residents (mean age, 83.8 years; 39 SARS-CoV-2-naive and 15 previously infected) and 63 healthcare workers (mean age, 45.8 years; 32 SARS-CoV-2-naive and 31 previously infected). Anti-spike (receptor-binding domain [RBD]) and anti-nucleocapsid antibody responses to BNT162b2 mRNA vaccination and their related factors were evaluated using pre- (shortly and 6 months after the second dose) and post-booster vaccination samples. The median anti-spike (RBD) IgG level in SARS-CoV-2-naive residents 6 months after the second dose was the lowest among the four groups, with a decreasing rate of over 90%. The median rate of increase before and after the third dose in SARS-CoV-2-naive residents was significantly higher than that in SARS-CoV-2-naive healthcare workers (64.1- vs. 37.0-fold, P = 0.003), with the highest level among the groups. The IgG ratio of SARS-CoV-2-naive residents to healthcare workers after the second and third doses changed from one-fifth (20%) to one-half (50%). The rate of increase after the third dose in previously infected individuals was three- to fourfold, regardless of residents or healthcare workers. Advanced aged nursing home residents, poor responders in the initial SARS-CoV-2 vaccine series, could obtain sufficient antibody responses with the additional booster dose, despite more than 6 months after the second.

Chong Y ，Goto T ，Tani N ，Yonekawa A ，Ikematsu H ，Shimono N ，Tanaka Y ，Akashi K ... -  《-》