Effectiveness of mRNA BNT162b2 Vaccine 6 Months after Vaccination among Patients in Large Health Maintenance Organization, Israel

SARS-CoV-2 Humoral Immunity Persists Following Rituximab Therapy

Long-term humoral immunity is mediated by short-lived plasma cells (replenished by memory B cells) and long-lived plasma cells. Their relative contributions are uncertain for immunity to SARS-CoV-2, especially given the widespread use of novel mRNA vaccines. Yet, this has far-reaching implications in terms of the need for regular booster doses in the general population and perhaps even revaccination in patients receiving B cell-depleting therapy. We aimed to characterise anti-SARS-CoV-2 antibody titres in patients receiving Rituximab following previous SARS-CoV-2 vaccination. We recruited 10 fully vaccinated patients (age: 16.9 ± 2.52 years) with childhood-onset nephrotic syndrome, not in relapse, receiving Rituximab for their steroid/calcineurin-inhibitor sparing effect. Antibodies to SARS-CoV-2 spike (S) and nucleocapsid (N) proteins were measured immediately prior to Rituximab and again ~6 months later, using the Roche Elecys® Anti-SARS-CoV-2 (S) assay. All ten patients were positive for anti-S antibodies prior to Rituximab, with six patients (60%) having titres above the upper limit of detection (>12,500 U/mL). Following Rituximab therapy, there was a reduction in anti-S titres (p = 0.043), but all patients remained positive for anti-S antibodies, with five patients (50%) continuing to have titres >12,500 U/mL. Six patients (60%) were positive for anti-N antibodies prior to Rituximab. Following Rituximab therapy, only three of these six patients remained positive for anti-N antibodies (p = 0.036 compared to anti-S seroreversion). Humoral immunity to SARS-CoV-2 is likely to be mediated in part by long-lived plasma cells.

Effect of tixagevimab/cilgavimab for pre-exposure prophylaxis during the China Omicron outbreak

OBJECTIVES

By the end of 2022, China had made a pivotal decision to optimize the COVID-19 policy. The dominant Omicron variant in China at that time was highly transmissible. In this study, we aimed to evaluate the real-world safety and efficacy of tixagevimab and cilgavimab against this background in China.

METHODS

Participants were enrolled if they were over 12 years old and were planning to receive tixagevimab or cilgavimab. All participants received intramuscular administration of tixagevimab (150 mg) and cilgavimab (150 mg). Data were collected on demographics, underlying illness, prior infection, vaccination, adverse events, and COVID-19 outcomes (e.g., infection rate, hospitalization rate, and severe disease).

RESULTS

During the study period, 168 (37.9%) of 443 who received tixagevimab/cilgavimab were diagnosed with SARS-CoV-2 infection. All infected patients had mild COVID-19. Two patients (0.5%) were hospitalized for COVID-19, but none of them were admitted to the ICU. None of the patients died during this study. 4 (0.9%) reported mild local adverse events, and no severe systemic adverse reactions were reported.

CONCLUSION

Tixagevimab/cilgavimab may have protected high-risk populations against infection with the Omicron variant, hospitalization and severe disease during the China COVID-19 pandemic.

Risk Stratification Model for Severe COVID-19 Disease: A Retrospective Cohort Study

Background: Risk stratification models have been developed to identify patients that are at a higher risk of COVID-19 infection and severe illness. Objectives To develop and implement a scoring tool to identify COVID-19 patients that are at risk for severe illness during the Omicron wave. Methods: This is a retrospective cohort study that was conducted in Israel’s second-largest healthcare maintenance organization. All patients with a new episode of COVID-19 between 26 November 2021 and 18 January 2022 were included. A model was developed to predict severe illness (COVID-19-related hospitalization or death) based on one-third of the study population (the train group). The model was then applied to the remaining two-thirds of the study population (the test group). Risk score sensitivity, specificity, and positive predictive value rates, and receiver operating characteristics (ROC) were calculated to describe the performance of the model. Results: A total of 409,693 patients were diagnosed with COVID-19 over the two-month study period, of which 0.4% had severe illness. Factors that were associated with severe disease were age (age > 75, OR-70.4, 95% confidence interval [CI] 42.8–115.9), immunosuppression (OR-4.8, 95% CI 3.4–6.7), and pregnancy (5 months or more, OR-82.9, 95% CI 53–129.6). Factors that were associated with a reduced risk for severe disease were vaccination status (patients vaccinated in the previous six months OR-0.6, 95% CI 0.4–0.8) and a prior episode of COVID-19 (OR-0.3, 95% CI 0.2–0.5). According to the model, patients who were in the 10th percentile of the risk severity score were considered at an increased risk for severe disease. The model accuracy was 88.7%. Conclusions: This model has allowed us to prioritize patients requiring closer follow-up by their physicians and outreach services, as well as identify those that are most likely to benefit from anti-viral treatment during the fifth wave of infection in Israel, dominated by the Omicron variant.

Preventive Behaviors and Information Sources during COVID-19 Pandemic: A Cross-Sectional Study in Japan

BACKGROUND

individual preventive behaviors are one of the key measures needed to prevent the spread of COVID-19. This study sought to identify the factors associated with the adoption of COVID-19 preventive measures, focusing specifically on information sources.

METHODS

we conducted a nationally representative cross-sectional survey of 30,053 Japanese adults in February 2021. The survey asked about socioeconomic, health-related, and psychological characteristics, attitudes toward immunization, and the use of information sources regarding COVID-19. We have constructed multivariable logistic regression to estimate the factors associated with the adoption of three preventive measures: 3Cs avoidance, hand hygiene and respiratory hygiene.

RESULTS

socioeconomic variables, psychological variables, and the use of information sources are significantly associated with the adoption of preventive measures. The more information sources one uses, the more likely one is to adopt preventive measures. Trust in healthcare professionals is positively associated with adopting preventive measures. On the other hand, negative correlations between trust in social media and preventive behaviors were observed.

CONCLUSIONS

encouraging access to multiple information sources, utilizing communication channels, and modifying messaging according to target groups are essential to promote COVID-19 preventive measures.

Effect of Vaccination Time Intervals on SARS-COV-2 Omicron Variant Strain Infection in Guangzhou: A Real-World Matched Case–Control Study

In April 2022, a COVID-19 outbreak caused by the Omicron variant emerged in Guangzhou. A case–control study was conducted to explore the relationship between vaccination intervals and SARS-CoV-2 infection in the real world. According to the vaccination dose and age information of the cases, a 1:4 matched case–control sample was established, finally including n = 242 for the case group and n = 968 for the control group. The results indicated that among the participants who received three vaccine doses, those with an interval of more than 300 days between the receipt of the first vaccine dose and infection (or the first contact with a confirmed case) were less likely to be infected with SARS-CoV-2 than those with an interval of less than 300 days (OR = 0.67, 95% CI = 0.46–0.99). After age-stratified analysis, among participants aged 18–40 years who received two doses of vaccine, those who received the second dose more than 30 days after the first dose were less likely to be infected with SARS-CoV-2 (OR = 0.53, 95% CI = 0.30–0.96). Our findings suggest that we need to extend the interval between the first dose and the second dose and further explore the optimal interval between the first and second and between the second and third doses in order to improve vaccine efficacy.

Current clinical status of new COVID-19 vaccines and immunotherapy

COVID-19, caused by SARS-CoV-2, is a positive-strand RNA belonging to Coronaviridae family, along with MERS and SARS. Since its first report in 2019 in Wuhan, China, it has affected over 530 million people and led to 6.3 million deaths worldwide until June 2022. Despite eleven vaccines being used worldwide already, new variants are of concern. Therefore, the governing bodies are re-evaluating the strategies for achieving universal vaccination. Initially, the WHO expected that vaccines showing around 50-80% efficacy would develop in 1-2 years. However, US-FDA announced emergency approval of the two m-RNA vaccines within 11 months of vaccine development, which enabled early vaccination for healthcare workers in many countries. Later, in January 2021, 63 vaccine candidates were under human clinical trials and 172 under preclinical development. Currently, the number of such clinical studies is still increasing. In this review, we have summarized the updates on the clinical status of the COVID-19 and the available treatments. Additionally, COVID-19 had created negative impacts on world's economy; affected agriculture, industries, and tourism service sectors; and majorly affected low-income countries. The review discusses the clinical outcomes, latest statistics, socio-economic impacts of pandemic and treatment approaches against SARS-CoV-2, and strategies against the new variant of concern. The review will help understand the current status of vaccines and other therapies while also providing insights about upcoming vaccines and therapies for COVID-19 management.

Determinants of Antibody Responses to SARS-CoV-2 Vaccines: Population-Based Longitudinal Study (COVIDENCE UK)

Antibody responses to SARS-CoV-2 vaccines vary for reasons that remain poorly understood. A range of sociodemographic, behavioural, clinical, pharmacologic and nutritional factors could explain these differences. To investigate this hypothesis, we tested for presence of combined IgG, IgA and IgM (IgGAM) anti-Spike antibodies before and after 2 doses of ChAdOx1 nCoV-19 (ChAdOx1, AstraZeneca) or BNT162b2 (Pfizer-BioNTech) in UK adults participating in a population-based longitudinal study who received their first dose of vaccine between December 2020 and July 2021. Information on sixty-six potential sociodemographic, behavioural, clinical, pharmacologic and nutritional determinants of serological response to vaccination was captured using serial online questionnaires. We used logistic regression to estimate multivariable-adjusted odds ratios (aORs) for associations between independent variables and risk of seronegativity following two vaccine doses. Additionally, percentage differences in antibody titres between groups were estimated in the sub-set of participants who were seropositive post-vaccination using linear regression. Anti-spike antibodies were undetectable in 378/9101 (4.2%) participants at a median of 8.6 weeks post second vaccine dose. Increased risk of post-vaccination seronegativity associated with administration of ChAdOx1 vs. BNT162b2 (adjusted odds ratio (aOR) 6.6, 95% CI 4.2−10.4), shorter interval between vaccine doses (aOR 1.6, 1.2−2.1, 6−10 vs. >10 weeks), poor vs. excellent general health (aOR 3.1, 1.4−7.0), immunodeficiency (aOR 6.5, 2.5−16.6) and immunosuppressant use (aOR 3.7, 2.4−5.7). Odds of seronegativity were lower for participants who were SARS-CoV-2 seropositive pre-vaccination (aOR 0.2, 0.0−0.6) and for those taking vitamin D supplements (aOR 0.7, 0.5−0.9). Serologic responses to vaccination did not associate with time of day of vaccine administration, lifestyle factors including tobacco smoking, alcohol intake and sleep, or use of anti-pyretics for management of reactive symptoms after vaccination. In a sub-set of 8727 individuals who were seropositive post-vaccination, lower antibody titres associated with administration of ChAdOx1 vs. BNT162b2 (43.4% lower, 41.8−44.8), longer duration between second vaccine dose and sampling (12.7% lower, 8.2−16.9, for 9−16 weeks vs. 2−4 weeks), shorter interval between vaccine doses (10.4% lower, 3.7−16.7, for <6 weeks vs. >10 weeks), receiving a second vaccine dose in October−December vs. April−June (47.7% lower, 11.4−69.1), older age (3.3% lower per 10-year increase in age, 2.1−4.6), and hypertension (4.1% lower, 1.1−6.9). Higher antibody titres associated with South Asian ethnicity (16.2% higher, 3.0−31.1, vs. White ethnicity) or Mixed/Multiple/Other ethnicity (11.8% higher, 2.9−21.6, vs. White ethnicity), higher body mass index (BMI; 2.9% higher, 0.2−5.7, for BMI 25−30 vs. <25 kg/m2) and pre-vaccination seropositivity for SARS-CoV-2 (105.1% higher, 94.1−116.6, for those seropositive and experienced COVID-19 symptoms vs. those who were seronegative pre-vaccination). In conclusion, we identify multiple determinants of antibody responses to SARS-CoV-2 vaccines, many of which are modifiable.

A quick scoping review of the first year of vaccination against the COVID-19 pandemic: Do we need more shots or time?

BACKGROUND

The emergence of new severe acute respiratory syndrome coronavirus 2 variants, along with the waning of vaccine-induced immunity, has increased breakthrough infections and urged booster jabs and debates. In the short term, the administration of booster doses has been reported to be safe and enhance severe acute respiratory syndrome coronavirus 2-specific neutralizing antibody levels. However, the effects of these doses on the pandemic trajectory and herd immunity are unclear. There is insufficient evidence that a third booster shot of the coronavirus disease 2019 (COVID-19) vaccine maintains longer immunity and covers new viral variants. The lack of sufficient evidence, combined with the fact that millions of people have not yet received 1 or 2 jabs of the COVID-19 vaccine, has raised concerns regarding the call for booster vaccinations.

METHODS

We conducted a quick scoping review to explore the literature on the need for a booster COVID-19 vaccination from January 1, 2021, to April 30, 2022.

RESULTS

Sixty-one relevant publications were identified, of which 17 were related to waning immunity after 2 doses of the vaccine among the general population or healthcare workers, 19 were related to the third or booster dose of vaccination after the second dose among the general population or healthcare workers, and 25 were related to booster dose among immunocompromised patient.

CONCLUSIONS

Initially, the need for a booster dose was equivocal; however, several studies demonstrated the benefit of the booster dose over time. Adequate scientific information is required regarding the administration of booster doses to the general population as well as the high-risk individuals.

Association Between AZD7442 (Tixagevimab-Cilgavimab) Administration and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection, Hospitalization, and Mortality

BACKGROUND

Intramuscular AZD7442 (tixagevimab-cilgavimab [Evusheld; AstraZeneca]) has been found effective among immunocompromised individuals (ICIs) in reducing SARS-CoV-2 infection and severe disease in ICIs. We evaluated the association between AZD7442 administration and SARS-CoV-2 infection and severe disease (COVID-19 hospitalization and all-cause mortality) among selected ICIs, during a fifth Omicron-dominated wave of COVID-19 (December 2021-April 2022) in Israel.

METHODS

ICIs aged ≥12 years identified in the Maccabi HealthCare Services database were invited by SMS/e-mail to receive AZD7442. Demographic information, comorbidities, coronavirus vaccination, and prior SARS-CoV-2 infection and COVID-19 outcome data (infection, severe disease) were extracted from the database. Rates of infection and severe disease were compared between those administered AZD7442 and those who did not respond to the invitation over a 3-month period.

RESULTS

Of all 825 ICIs administered AZD7442, 29 (3.5%) became infected with SARS-CoV-2 compared with 308 (7.2%) of 4299 ICIs not administered AZD7442 (P < .001). After adjustment, the AZD7442 group was half as likely to become infected with SARS-CoV-2 than the nonadministered group (OR: .51; 95% CI: .30-.84). One person in the AZD7442 group (0.1%) was hospitalized for COVID-19 compared with 27 (0.6%) in the nonadministered group (P = .07). No mortality was recorded among the AZD7442 group compared with 40 deaths (0.9%) in the nonadministered group (P = .005). After adjustment, ICIs administered AZD7442 were 92% less likely to be hospitalized/die than those not administered AZD7442 (OR: .08; 95% CI: .01-.54).

CONCLUSIONS

AZD7442 among ICIs may protect against Omicron variant infection and severe disease and should be considered for pre-exposure prophylactic AZD7442.

Humoral immune response characterization of heterologous prime-boost vaccination with CoronaVac and BNT162b2

Background

Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has proven to be a successful strategy for prevent severe infections. CoronaVac and BNT162b2 are the most used vaccines worldwide, but their use in heterologous vaccination schedules is still subjected to evaluation.

Methods

Fifty healthy individuals who received heterologous prime-boost vaccination with CoronaVac and BNT162b2 were enrolled in a post-vaccination serological follow-up longitudinal prospective study. We evaluated specific serum anti-receptor binding domain (RBD) IgG antibody levels, and their capacity to block RBD-ACE2 interaction with a surrogate neutralization assay. In 20 participants, we assessed antibody binding kinetics by surface plasmon resonance, and Fc-mediated functions by ADCC and ADCP reporter assays.

Results

Our baseline seronegative cohort, displayed seroconversion after two doses of CoronaVac and an important decrease in serum anti-RBD IgG antibodies levels 80 days post-second dose. These levels increased significantly early after the third dose with BNT162b2, but 73 days after the booster we found a new fall. Immunoglobulin functionalities showed a similar behavior.

Conclusions

The heterologous prime-boost vaccination with CoronaVac and BNT162b2 generated an impressive increase in serum anti-RBD specific antibody levels followed by a drop. Nevertheless, these titers remained well above those found in individuals only vaccinated with CoronaVac in the same elapsed time. Serum IgG levels showed high correlation with antibody binding analysis, their capacity to block RBD-ACE2 interaction, and Fc-effectors mechanisms. Our work sheds light on the humoral immune response to heterologous vaccination with CoronaVac and BNT162b2, to define a post-vaccination correlate of protection against SARS-CoV-2 infection and to discuss the scheduling of future vaccine boosters in general population.

Effectiveness of a fourth dose of covid-19 mRNA vaccine against the omicron variant among long term care residents in Ontario, Canada: test negative design study

OBJECTIVES

To estimate the marginal effectiveness of a fourth versus third dose and the vaccine effectiveness of mRNA covid-19 vaccines BNT162b2 and mRNA-1273 against any infection, symptomatic infection, and severe outcomes (hospital admission or death) related to the omicron variant.

DESIGN

Test negative design.

SETTING

Long term care facilities in Ontario, Canada, 30 December 2021 to 27 April 2022.

PARTICIPANTS

After exclusions, 61 344 residents aged 60 years or older across 626 long term care facilities in Ontario, Canada who were tested for SARS-CoV-2 were included.

MAIN OUTCOME MEASURES

Laboratory confirmed omicron SARS-CoV-2 infection (any and symptomatic) by reverse transcription polymerase chain reaction (RT-PCR), and hospital admission or death. Multivariable logistic regression was used to estimate marginal effectiveness (four versus three doses) and vaccine effectiveness (two, three, or four doses versus no doses) while adjusting for personal characteristics, comorbidities, week of test, and previous positive SARS-CoV-2 test result more than 90 days previously.

RESULTS

13 654 residents who tested positive for omicron SARS-CoV-2 infection and 205 862 test negative controls were included. The marginal effectiveness of a fourth dose (95% of vaccine recipients received mRNA-1273 as the fourth dose) seven days or more after vaccination versus a third dose received 84 or more days previously was 19% (95% confidence interval 12% to 26%) against infection, 31% (20% to 41%) against symptomatic infection, and 40% (24% to 52%) against severe outcomes. Vaccine effectiveness in vaccine recipients (compared with unvaccinated) increased with each additional dose, and for a fourth dose was 49% (95% confidence interval 43% to 54%) against infection, 69% (61% to 76%) against symptomatic infection, and 86% (81% to 90%) against severe outcomes.

CONCLUSIONS

The findings suggest that compared with a third dose of mRNA covid-19 vaccine, a fourth dose improved protection against infection, symptomatic infection, and severe outcomes among long term care residents during an omicron dominant period. A fourth vaccine dose was associated with strong protection against severe outcomes in vaccinated residents compared with unvaccinated residents, although the duration of protection remains unknown.

Heterologous booster COVID-19 vaccination elicited potent immune responses in HCWs

The objective of our study was to evaluate the antibody responses of health care workers (HCWs) who were vaccinated with booster dose BNT162b2 6 months after 2 doses of the CoronoVac vaccine. The study included 318 HCWs vaccinated with inactive CoronaVac SARS-CoV-2 vaccine in 2 doses. Anti-spike/RBD IgG levels were measured immediately before and 1 month after the booster dose. In the sixth month after CoronaVac vaccination, the median of antibody levels of 1212.02 AU/ML, while it was 9283 AU/mL after BNT162b2 vaccination. IgG antibody titers of over 1050 AU/mL (which is equivalent to 1:80 dilution in the plaque reduction neutralization test) were detected in HCWs 15.09% and 97.8%, respectively. Our results showed that antibody titers increased 8-fold after the booster dose. We believe that the administration of the mRNA vaccine as a booster dose can provide more effective protection against COVID-19 infection, especially in individuals with risk factors.

Follow up of the Humoral Response in Healthcare Workers after the Administration of Two Dose of the Anti SARS-CoV-2 Vaccines-Effectiveness in Delta Variant Breakthrough Infections

The implementation of vaccination among healthcare workers (HCWs) allowed the management of the pandemic in a manner that differed from that in the first waves. It has been demonstrated that the mRNA vaccines elicit good humoral responses but that there are still breakthrough infections. In summer 2021, a fifth wave emerged, despite the good coverage of HCWs in Spain. We aimed to study the SARS-CoV-2 IgG antibody levels as a marker to predict the possibility of Delta variant infections after vaccination after a seroepidemiological campaign. Of the 5000 participants, a total of 4902 (98.04%) showed a positive result in the serological anti-S test and only 98 (1.96%) were negative. Among the 4368 fully vaccinated participants, only in five cases was the serology negative. Of the total number of participants that received antibody results during the study, 162 were PCR positive in the subsequent two months. Among these, 151 were fully vaccinated (two doses). Significant differences between antibody BAU/mL levels were found between PCR positive and non-PCR positive participants (p < 0.01). The median of BAU/mL was higher in those vaccinated patients with no infection (1260 BAU/mL; 465−2080) versus infected patients (661 BAU/mL; 361−2080). These data support the idea that vaccines play an important role in the control of the pandemic, especially among HCWs at the time of the Delta variant circulation. More studies with other variants of concern must be performed in order to establish a correlation between the levels of IgG and the new infections.

Temporal changes in spike IgG levels after two doses of BNT162b2 vaccine in Japanese healthcare workers: Do spike IgG levels at 3 months predict levels 6 or 8 months after vaccination?

Background

Accurate timing of BNT162b2 boosters to prevent breakthrough infections of coronavirus disease 2019 (COVID-19) requires reliable estimates of immune status. We hypothesized that spike IgG levels at 3 months after two doses of the BNT162b2 vaccine might predict subsequent spike IgG levels.

Methods and results

Spike IgG levels were tested at 3, 6, and 8 months after the second dose of the BNT162b2 vaccine in 251 Japanese health care workers (median age: 39 years, female: 187).

The median level of spike IgG was 2,882 AU/mL at 3 months. This decreased to 875 AU/mL at 6 months and 579 AU/mL at 8 months. There were good correlations of log-transformed spike IgG levels between 3 and 6 months (r = 0.86) and between 3 and 8 months (r = 0.82). The correlation further improved after excluding three subjects who had possible COVID-19 infections (r = 0.91, r = 0.86). Log-transformed spike IgG levels at 6 or 8 months yields the following equation:

log spike IgG at 6 (8) months = 0.92 (0.86) X log spike IgG at 3 months– 0.23 (0.18). Predicted spike IgG at 6 months of ≥ 300 or < 300 AU/mL had 98% sensitivity, 47% specificity, and 94% accuracy for discriminating subjects whose actual spike IgG titers at 6 months were above or below 300 AU/mL. Corresponding values of predicted spike IgG at 8 months were 97%, 70%, and 93%, respectively.

Conclusions

We conclude that predictive formulae using spike IgG levels at 3 months after two-dose vaccination with BNT162b2 reliably estimate subsequent spike IgG levels up to 8 months and provide useful information in terms of vaccination booster timing.

Complete (Humoral and Cellular) Response to Vaccination against COVID-19 in a Group of Healthcare Workers-Assessment of Factors Affecting Immunogenicity

Vaccination is the best way to limit the extent of the COVID pandemic. Knowledge of the duration of the immune response will allow the planning of a vaccination protocol. This study aims to validate the complete (humoral and cellular) immune responses over time in large population groups following the full vaccination of healthcare professionals in real-life conditions and to assess the relationship between antibody levels and T-cell activity in relation to the characteristics of the study group. The samples for the study were obtained from volunteers (staff of two hospitals) on three occasions: before vaccination, T0, then 4–9 weeks after full vaccination (two doses BNT162b2), T1, and 7–9 months after vaccination, T2. The humoral response was investigated by the titre of anti-SARS-CoV-2 IgG antibodies to S1 protein. Assays were performed three times at intervals. The cellular response was assessed in a subgroup of 189 subjects by QuanT-Cell SARS-CoV-2 (IGRA). The assay was performed once. A group of 344 subjects fully vaccinated with the BNT162b2 vaccine were included in the study. The humoral response was observed in 100% of subjects at both 4–7 weeks and 7–9 months, but antibody titres fell by almost 90% in this interval. The cellular response was observed in 94% (177/189) of subjects 7–9 months after the second dose of vaccine. In subjects with a negative cellular response, eight out of 12 smoked. A factor associated with greater immunogenicity of vaccination was past SARS-CoV-2 infection. The administration of full BNT162b2 vaccination (two doses) induces humoral and cellular responses detectable even more than six months after vaccination. Smoking may be a factor associated with impaired cellular response to vaccination.

SARS-CoV-2 Omicron variant: Immune escape and vaccine development

New genetic variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) constantly emerge through unmitigated spread of the virus in the ongoing Coronavirus disease 2019 pandemic. Omicron (B.1.1.529), the latest variant of concern (VOC), has so far shown exceptional spread and infectivity and has established itself as the dominant variant in recent months. The SARS-CoV-2 spike glycoprotein is a key component for the recognition and binding to host cell angiotensin-converting enzyme 2 receptors. The Omicron variant harbors a cluster of substitutions/deletions/insertions, and more than 30 mutations are located in spike. Some noticeable mutations, including K417N, T478K, N501Y, and P681H, are shared with the previous VOCs Alpha, Beta, Gamma, or Delta variants and have been proven to be associated with higher transmissibility, viral infectivity, and immune evasion potential. Studies have revealed that the Omicron variant is partially resistant to the neutralizing activity of therapeutic antibodies and convalescent sera, which poses significant challenges for the clinical effectiveness of the current vaccines and therapeutic antibodies. We provide a comprehensive analysis and summary of the epidemiology and immune escape mechanisms of the Omicron variant. We also suggest some therapeutic strategies against the Omicron variant. This review, therefore, aims to provide information for further research efforts to prevent and contain the impact of new VOCs during the ongoing pandemic.

Comparison of Neutralizing Antibody Responses at 6 Months Post Vaccination with BNT162b2 and AZD1222

Along with their level of protection against COVID-19, SARS-CoV-2-specific antibodies decline over time following vaccination with BNT162b2. However, relevant data on AZD1222 are scarce. In this context, the aim of this study was to compare SARS-CoV-2 neutralizing antibody (NAb) levels at one, three and six months after second vaccination with the BNT162b2 mRNA vaccine and the ChAdOx1 (AZD1222) viral vector vaccine (NCT04743388). The measurements were performed with the GenScript’s cPassTM SARS-CoV-2 NAbs Detection Kit (GenScript, Inc.; Piscataway, NJ, USA). Overall, data from 282 individuals were included (BNT162b2 n = 83, AZD1222 n = 199). Both vaccines induced strong NAbs responses at 1 month following vaccination. Interestingly, NAb activity seemed superior with BNT162b2 compared with AZD1222. A gradual decline in NAbs titers was evident at 3 and 6 months post vaccination with both vaccines. However, the superiority of NAb response with BNT162b2 over AZD1222 remained consistent at all time points examined. Furthermore, the elimination rate of the NAb titer was higher throughout during the study period for those vaccinated with AZD1222 compared with BNT162b2. Age, gender, body mass index or comorbidities did not have a significant impact on NAbs levels over time. Our results may inform public health policies regarding the timing of booster COVID-19 vaccine shots.

Incidence of positive SARS-CoV-2 PCR after COVID-19 vaccination with up to eight months of follow-up: Real life data from the Capital Region of Denmark

Background

COVID-19 vaccines are implemented worldwide in efforts to curb the pandemic. This study investigates the risk of a positive SARS-CoV-2 RT-PCR test following BNT162b2 vaccination in a large real-life population in Denmark.

Methods

Vaccination status and positive SARS-CoV-2 RT-PCR results from adults in the Capital Region of Denmark (n=1,549,488) were obtained from national registries. PCR testing was free and widely available. The number of positive PCR tests per individual at risk were calculated as weekly rates. Time to positive PCR test was modelled using Kaplan-Meier methods and hazard ratios (HR) were calculated using Cox regression.

Results

1,119,574 individuals received first dose of BNT162b2 and 1,088,879 received a second dose of BNT162b2. Individuals were followed up to 8.7 months after first dose (median: 5.5 months, IQR:4.1-8.7). Rates of PCR-confirmed SARS-CoV-2 infection two to four months after the second dose were 0.21, 0.33 and 0.36 per 1000 individuals per week at risk for July, August and September, respectively. Four or more months after the second dose, the rates were 0.56, 0.76 and 0.53 per 1000 individuals per week at risk for July, August and September, respectively. HR of SARS-CoV-2 infection after the second dose was 0.2 (95% CI: 0.05-0.48, p=0.001) for individuals with eight months follow-up.

Conclusion

Individuals who received two doses of the BNT162b2 COVID-19 vaccine had a low risk of breakthrough-infection after up to 8 months of follow-up. However, there was a tendency towards higher rates with longer follow-up.

COVID-19 post-vaccination in healthcare workers and vaccine effectiveness, Brazil, 2021

OBJECTS

This study aimed to describe COVID-19 cases in healthcare workers at a large tertiary hospital, after a vaccination campaign, to understand the individual characteristics, timeliness, symptomatology, and severity of the conditions.

METHODS

The COVID-19 reporting files from the hospital's healthcare workers and their records in the vaccine registry were analyzed, regarding vaccination status, symptoms, sociodemographic characteristics, comorbidities, and outcomes. Vaccination descriptive analysis was carried out and the impact and effectiveness of vaccination in relation to symptomatic infection and hospitalization were estimated.

RESULTS

In a total of 696 PCR-confirmed COVID-19 patients, vaccination coverage for the 1^st and 2^nd dose was 92.8% and 85.5%. Patients with complete doses had a mean interval of 96.8 days between vaccination and the onset of symptoms. Of the 664 participants with available clinical data, 165 had at least 1 comorbidity. During the study, 12 patients were hospitalized, 58.3% with a complete vaccination schedule. Three of this group died. The effectiveness of vaccination for symptomatic cases and hospitalization was 22.1% and 69.0%, respectively. The impact of vaccination on symptomatic cases and hospitalization was 81.4% and 89.7%, respectively.

DISCUSSION

The majority of COVID-19 cases in the study were classified as mild. The impact of vaccination for confirmed cases was significant, both in reducing the incidence of symptomatic cases and hospitalizations. The presence of comorbidities in approximately ¼ of the patients increased the risk of these individuals. The mean time interval between diagnosis and the 2^nd dose of vaccine was longer in the hospitalized group, reinforcing the protective decline over longer periods.