Abstract Antibody responses are an important part of immunity after Coronavirus Disease 2019 (COVID-19) vaccination. However, antibody trajectories and the associated duration of protection after a second vaccine dose remain unclear. In this study, we investigated anti-spike IgG antibody responses and correlates of protection after second doses of ChAdOx1 or BNT162b2 vaccines for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the United Kingdom general population. In 222,493 individuals, we found significant boosting of anti-spike IgG by the second doses of both vaccines in all ages and using different dosing intervals, including the 3-week interval for BNT162b2. After second vaccination, BNT162b2 generated higher peak levels than ChAdOX1. Older individuals and males had lower peak levels with BNT162b2 but not ChAdOx1, whereas declines were similar across ages and sexes with ChAdOX1 or BNT162b2. Prior infection significantly increased antibody peak level and half-life with both vaccines. Anti-spike IgG levels were associated with protection from infection after vaccination and, to an even greater degree, after prior infection. At least 67% protection against infection was estimated to last for 2–3 months after two ChAdOx1 doses, for 5–8 months after two BNT162b2 doses in those without prior infection and for 1–2 years for those unvaccinated after natural infection. A third booster dose might be needed, prioritized to ChAdOx1 recipients and those more clinically vulnerable. 

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Antibody responses and correlates of protection in the general population after two doses of the ChAdOx1 or BNT162b2 vaccines

Two doses of Pfizer/BioNTech BNT162b2 mRNA vaccine elicit robust severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-neutralizing antibodies with frequent adverse events. Here, by applying a high-dimensional immune profiling on 92 vaccinees, we identify six vaccine-induced immune dynamics that correlate with the amounts of neutralizing antibodies, the severity of adverse events, or both. The early dynamics of natural killer (NK)/monocyte subsets (CD16+ NK cells, CD56high NK cells, and non-classical monocytes), dendritic cell (DC) subsets (DC3s and CD11c- Axl+ Siglec-6+ [AS]-DCs), and NKT-like cells are revealed as the distinct cell correlates for neutralizing-antibody titers, severity of adverse events, and both, respectively. The cell correlates for neutralizing antibodies or adverse events are consistently associated with elevation of interferon gamma (IFN-γ)-inducible chemokines, but the chemokine receptors CCR2 and CXCR3 are expressed in distinct manners between the two correlates: vaccine-induced expression on the neutralizing-antibody correlate and constitutive expression on the adverse-event correlate. The finding may guide vaccine strategies that balance immunogenicity and reactogenicity. 

http://www.cell.com/article/S2666379122001562/pdf

Distinct immune cell dynamics correlate with the immunogenicity and reactogenicity of SARS-CoV-2 mRNA vaccine

COVID-19 vaccines have been developed to compact the current SARS-CoV-2 pandemic and have been administered to people all over the world. These vaccines have been quite effective in reducing the possibility of severe illness, hospitalization and death. However, the recent emergence of Variants of Concern specifically the delta variant, B.1.617.2, had resulted in additional waves of the pandemic.We aim to review the literature to understand the transmission and disease severity, and determine the efficacy of the current COVID-19 vaccines. We searched Pubmed, Scopus, and Embase till August 4th 2021, and used the search terms "delta variant", "vaccinations"," breakthrough infections", and "neutralizing antibody". For the meta-analysis, 21 studies were screened in particular and five articles (148,071 cases) were included in the study, and only four were analyzed in the meta-analysis.In this review, both in vitro and in vivo studies showed significant reductions in neutralization rates against delta variants for vaccinated individuals and convalescent patients with prior history of COVID-19. However, There was a lower incidence of infection with SARS-CoV-2 due to Delta variant was found after the second dose of Pfizer-BioNTech, Oxford-AstraZeneca and Moderna vaccines.In fully vaccinated individuals, symptomatic infection with the delta variant was significantly reduced, and therefore, vaccinations play an important role to assist the fight against delta variant. 

/pdf/implication-of-the-emergence-of-the-delta-b-1-617-2-variants-evdfmwuk.pdf

Implication of the emergence of the delta (B.1.617.2) variants on vaccine effectiveness

The humoral and cellular immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) upon the coronavirus disease 2019 (COVID-19) vaccination remain to be clarified. Hence, we aimed to investigate the long-term chronological changes in SARS-CoV-2 specific IgG antibody, neutralizing antibody, and T cell responses during and after receiving the BNT162b2 vaccine. We performed serological, neutralization, and T cell assays among 100 hospital workers aged 22-73 years who received the vaccine. We conducted seven surveys up to 8 months after the second vaccination dose. SARS-CoV-2 spike protein-specific IgG (IgG-S) titers and T cell responses increased significantly following the first vaccination dose. The highest titers were observed on day 29 and decreased gradually until the end of the follow-up period. There was no correlation between IgG-S and T cell responses. Notably, T cell responses were detected on day 15, earlier than the onset of neutralizing activity. This study demonstrated that both IgG-S and T cell responses were detected before acquiring sufficient levels of SARS-CoV-2 neutralizing antibodies. These immune responses are sustained for approximately 6 to 10 weeks but not for 7 months or later following the second vaccination, indicating the need for the booster dose (i.e., third vaccination). 

/pdf/sars-cov-2-specific-t-cell-and-humoral-immune-responses-upon-2e976qg1.pdf

SARS-CoV-2 specific T cell and humoral immune responses upon vaccination with BNT162b2: a 9 months longitudinal study

Use of heated tobacco products, moderate alcohol drinking, and anti-SARS-CoV-2 IgG antibody titers after BNT162b2 vaccination among Japanese healthcare workers

While mRNA vaccines against SARS-CoV-2 are exceedingly effective in preventing symptomatic infection, their immune response features remain to be clarified. In the present prospective study, 225 healthy individuals in Japan, who received two BNT162b2 doses, were enrolled. Correlates of BNT162b2-elicited SARS-CoV-2-neutralizing activity (50% neutralization titer: NT50; assessed using infectious virions) with various determinants were examined and the potency of sera against variants of concerns was determined. Significant rise in NT50s was seen in sera on day 28 post-1st dose. A moderate inverse correlation was seen between NT50s and ages, but no correlation seen between NT50s and adverse effects. NT50s and SARS-CoV-2-S1-binding-IgG levels on day 28 post-1st dose and pain scores following the 2nd dose were greater in women than in men. The average half-life of NT50s was ~ 68 days, and 23.6% (49 out of 208 individuals) failed to show detectable neutralizing activity on day 150. While sera from elite-responders (NT50s > 1,500: the top 4% among the participants) potently to moderately blocked all variants of concerns examined, some sera with low NT50s failed to block the B.1.351-beta strain. Since BNT162b2-elicited immunity against SARS-CoV-2 is short, an additional vaccine or other protective measures are needed.

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Correlates of neutralizing/SARS-CoV-2-S1-binding antibody response with adverse effects and immune kinetics in BNT162b2-vaccinated individuals.

Background While mRNA vaccines against SARS-CoV-2 have been exceedingly effective in preventing symptomatic viral infection, the features of immune response remain to be clarified. Methods In the present prospective observational study, 225 healthy individuals in Kumamoto General Hospital, Japan, who received two BNT162b2 doses in February 2021, were enrolled. Correlates of BNT162b2-elicited SARS-CoV-2-neutralizing activity (50% neutralization titer: NT 50 ; assessed using infectious virions and live target cells) with SARS-CoV-2-S1-binding-IgG and -IgM levels, adverse effects (AEs), ages, and genders were examined. The average half-life of neutralizing activity and the average time length for the loss of detectable neutralizing activity were determined and the potency of serums against variants of concerns was also determined. Findings Significant rise in NT 50 s was seen in serums on day 28 post-1st dose. A moderate inverse correlation was seen between NT 50 s and ages, but no correlation was seen between NT 50 s and AEs. NT 50 s and IgG levels on day 28 post-1st dose and pain scores following the 2nd shot were greater in women than in men. The average half-life of neutralizing activity in the vaccinees was approximately 67.8 days and the average time length for their serums to lose the detectable neutralizing activity was 198.3 days. While serums from elite-responders (NT 50 s>1,500-fold: the top 4% among all participants' NT 50 s) potently to moderately blocked the infectivity of variants of concerns, some serums with moderate NT 50 s failed to block the infectivity of a beta strain. Interpretation BNT162b2-elicited immune response has no significant association with AEs. BNT162b2-efficacy is likely diminished to under detection limit by 6-7 months post-1st shot. High-level neutralizing antibody-containing serums potently to moderately block the infection of SARS-CoV-2 variants; however, a few moderate-level neutralizing antibody-containing serums failed to do so. If BNT162b2-elicited immunity memory is short, an additional vaccine or other protective measures would be needed. Research in context Evidence before this study: While mRNA vaccines against SARS-CoV-2 have been exceedingly effective in preventing symptomatic viral infection, the salient features of immune response including the persistence of protection remain to be clarified. There is a report that anti-SARS-CoV-2 antibodies persist through 6 months after the second dose of mRNA-1273 vaccine (Doria-Rose et al. N Engl J Med . 2021;384:2259-2261); however, more definite immune kinetics following mRNA-vaccine-elicited protection have to be clarified. The mRNA-vaccine-elicited protection against SARS-CoV-2 variants are also to be determined. Added value of this study: In the present prospective study, 225 twice-BNT162b2-dose-receiving individuals in Japan were enrolled. No significant correlation was seen between 50% neutralizing titers (NT 50 s), determined by using infectious SARS-CoV-2 virions and live target cells, and adverse effects. Largely, NT 50 s and IgG levels were greater in women than in men. Following 28 days post-2 nd shot, significant reduction was seen in NT 50 s, IgG, and IgM levels. The average half-life of NT 50 s was ∼68 days and the average time-length for participants' serums to lose the detectable activity was ∼198 days. Although serums from elite-responders potently to moderately blocked the infectivity of variants of concerns, some serums with moderate NT 50 s failed to block the infectivity of a beta strain. Implications of all the available evidence: BNT162b2 efficacy is likely to be diminished to under detection limit by 6-7 months post-1 st shot on average. Individuals with moderate NT 50 s may fail to block beta variants. If BNT162b2-elicited immune memory is lost soon, additional vaccine(s) or other protective means would be needed.

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Correlates of Neutralizing/SARS-CoV-2-S1-binding Antibody Response with Adverse Effects and Immune Kinetics in BNT162b2-Vaccinated Individuals

The present study aimed to identify factors associated with retention in HIV/AIDS care among migrant patients who visited the outpatient clinic of the AIDS Clinical Center, National Center for Global Health and Medicine in Tokyo, Japan. We reviewed the records of 551 selected (78 non-Japanese and 473 Japanese) patients who started visiting our clinic between 2011 and 2014. A total of 390 patients (70.8%: 38 non-Japanese and 352 Japanese) continued their visits during the study: from the date of their first visit to the end of 2015. The difference in retention rate was not significant (Incidence Rate Ratio (IRR) = 0.89, p = 0.27), but the loss-to-follow-up cases were considerably high among non-Japanese patients (n = 13, Incidence rate (IR) = 24.6 per 100,000 person-days, IRR = 3.65, p<0.01 after adjusting for time since diagnosis). The results showed, nevertheless, that there was no apparent association between retention and factors peculiar to non-Japanese. Twelve out of thirteen lost-to-follow-up non-Japanese patients held legal status to reside in Japan and were eligible for public health services. Nine had limited fluency in Japanese language, and six used alternative verbal communication. Further studies are needed to identify the factors responsible for the high dropout rate and to improve the care of migrant patients living with HIV/AIDS.

Mari Kinoshita

Papers

Correlates of neutralizing/SARS-CoV-2-S1-binding antibody response with adverse effects and immune kinetics in BNT162b2-vaccinated individuals.

Correlates of Neutralizing/SARS-CoV-2-S1-binding Antibody Response with Adverse Effects and Immune Kinetics in BNT162b2-Vaccinated Individuals

Migrant patients living with HIV/AIDS in Japan: Review of factors associated with high dropout rate in a leading medical institution in Japan.