Comparison of mRNA-1273 and BNT162b2 Vaccines on Breakthrough SARS-CoV-2 Infections, Hospitalizations, and Death During the Delta-Predominant Period

Seroconversion rate after primary vaccination with two doses of BNT162b2 versus mRNA-1273 in solid organ transplant recipients: a systematic review and meta-analysis

Background

In the general population, the seroconversion rate after primary vaccination with two doses of an anti-severe acute respiratory syndrome coronavirus 2 messenger RNA (mRNA) vaccine reaches nearly 100%, with significantly higher antibody titers after mRNA-1273 vaccination compared to BNT162b2 vaccination. Here we performed a systematic review and meta-analysis to compare the antibody response after two-dose mRNA-1273 versus BNT162b2 vaccination in solid organ transplant (SOT) recipients.

Methods

A systematic literature review was performed using PubMed, Web of Science and the Cochrane Library and original research papers were included for a meta-analysis to calculate vaccine-specific seroconversion rates for each of the mRNA vaccines. Next, the pooled relative seroconversion rate was estimated.

Results

Eight studies that described the development of antibodies against receptor-binding domain (RBD) and/or spike protein were eligible for meta-analysis. Two of these studies also reported antibody titers. The meta-analysis revealed lower seroconversion rates in SOT recipients vaccinated with two doses of BNT162b2 {44.3% [95% confidence interval (CI) 34.1–54.7]} as compared with patients vaccinated with two doses of mRNA-1273 [58.4% (95% CI 47.2–69.2)]. The relative seroconversion rate was 0.795 (95% CI 0.732–0.864).

Conclusions

This systematic review and meta-analysis indicates that in SOT recipients, higher seroconversion rates were observed after vaccination with mRNA-1273 compared with BNT162b2.

Breakthrough SARS-CoV-2 Infections, Hospitalizations, and Mortality in Vaccinated Patients With Cancer in the US Between December 2020 and November 2021

Question

What are the time trends, risks, and outcomes of breakthrough SARS-CoV-2 infections in vaccinated patients with cancer in the US between December 2020 and November 2021?

Findings

In this cohort study of a nationwide database of electronic health records of 636 465 vaccinated patients, the 45 253 vaccinated patients with cancer had significantly higher risk for breakthrough SARS-CoV-2 infections than propensity score–matched patients without cancer, with marked heterogeneity among 12 common cancers, including solid tumors and hematologic cancers, most common in patients with active cancer within the past year. Breakthrough infections in patients with cancer were associated with significant and substantial risks for hospitalizations and mortality.

Meaning

With the emergence of SARS-CoV-2 virus variants and the waning immunity of vaccines, the findings raise the consideration for the development and implementation of enhanced mitigation strategies in vaccinated patients with specific cancers, especially those undergoing active cancer care.

Importance

Limited data have been presented to examine breakthrough SARS-CoV-2 infections, hospitalizations, and mortality in vaccinated patients with cancer in the US.

Objectives

To examine the risk of breakthrough SARS-CoV-2 infection, hospitalizations, and mortality in vaccinated patients with cancer between December 2020 and November 2021.

Design, Setting, and Participants

Retrospective cohort study of electronic health records (EHRs) of vaccinated patients from a multicenter and nationwide database in the US during the period of December 2020 through November 2021. The study population comprised patients who had documented evidence of vaccination (2 doses of Moderna or Pfizer-BioNTech or single dose of Janssen/Johnson & Johnson vaccines) in their EHRs from December 2020 to November 2021 and had no SARS-CoV-2 infection prior to vaccination.

Exposures

The 12 most common cancers combined and separately; recent vs no recent encounter for cancer; and breakthrough SARS-CoV-2 infection.

Main Outcomes and Measures

Time trends of incidence proportions of breakthrough SARS-CoV-2 infections from December 2020 to November 2021 in vaccinated patients with all cancer; cumulative risks of breakthrough infections in vaccinated patients for all cancer and 12 common cancer types; hazard ratios (HRs) and 95% CIs of breakthrough infections between propensity score–matched patients with vs without cancer and between propensity score–matched patients with cancer who had a recent medical encounter for cancer vs those who did not; overall risks, HRs, and 95% CIs of hospitalizations and mortality in patients with cancer who had breakthrough infections vs those who did not.

Results

Among 45 253 vaccinated patients with cancer (mean [SD] age, 68.7 [12.4] years), 53.5% were female, 3.8% were Asian individuals, 15.4% were Black individuals, 4.9% were Hispanic individuals, and 74.1% were White individuals. Breakthrough SARS-CoV-2 infections in patients with cancer increased from December 2020 to November 2021 and reached 52.1 new cases per 1000 persons in November 2021. The cumulative risk of breakthrough infections in patients with all cancer was 13.6%, with highest risk for pancreatic (24.7%), liver (22.8%), lung (20.4%), and colorectal (17.5%) cancers, and lowest risk for thyroid (10.3%), endometrial (11.9%), and breast (11.9%) cancers, vs 4.9% in the noncancer population (P < .001). Patients with cancer had significantly increased risk for breakthrough infections vs patients without cancer (HR, 1.24; 95% CI, 1.19-1.29), with greatest risk for liver (HR, 1.78; 95% CI, 1.38-2.29), lung (HR, 1.73; 95% CI, 1.50-1.99), pancreatic (HR, 1.64; 95% CI, 1.24-2.18), and colorectal (HR, 1.53; 95% CI, 1.32-1.77) cancers and lowest risk for thyroid (HR, 1.07; 95% CI, 0.88-1.30) and skin (HR, 1.17; 95% CI, 0.99-1.38) cancers. Patients who had medical encounters for cancer within the past year had higher risk for breakthrough infections than those who did not (HR, 1.24; 95% CI, 1.18-1.31). Among patients with cancer, the overall risk for hospitalizations and mortality was 31.6% and 3.9%, respectively, in patients with breakthrough infections, vs 6.7% and 1.3% in those without breakthrough infections (HR for hospitalization: 13.48; 95% CI, 11.42-15.91; HR for mortality: 6.76; 95% CI, 4.97-9.20).

Conclusions and Relevance

This cohort study showed significantly increased risks for breakthrough infection in vaccinated patients with cancer, especially those undergoing active cancer care, with marked heterogeneity among specific cancer types. Breakthrough infections in patients with cancer were associated with significant and substantial risks for hospitalizations and mortality.

Humoral Response in Hemodialysis Patients Following COVID-19 Vaccination and Breakthrough Infections during Delta and Omicron Variant Predominance

Background: The advancement of COVID-19 vaccination programs globally has been viewed as an integral strategy to reduce both the number of COVID-19 cases and consequential complications of COVID-19, particularly for high-risk patient groups. There are limited data on the antibody response and protection from disease infection and severity in patients requiring hemodialysis (HD) following COVID-19 vaccination during the Delta and Omicron variant predominance. We conducted a study aiming to evaluate humoral immunity derived from two different COVID-19 vaccines administered to our in-centre HD population and investigated the characteristics of breakthrough COVID-19 infections occurring post-vaccination within this population. Methods: This is a prospective observational study including patients receiving HD at Salford Royal Hospital. The first and second doses of COVID-19 vaccinations (Pfizer BioNTech BNT162b2 or Oxford AstraZeneca ChAdOx1 nCoV-19) were administered to this patient cohort since January 2021. The incidence of any breakthrough COVID-19 infections occurring in double vaccinated patients between 1 April 2021 and 15 January 2022 was recorded. Patients were screened weekly with nasal and pharyngeal nasopharyngeal swabs for real-time Reverse Transcription Polymerase Chain Reaction (rRT-PCR) for COVID-19, whilst SARS-CoV-2 antibody testing was performed alongside monthly routine HD bloods. Results: Four hundred eleven patients receiving HD were included in this study, of which 170 of 178 patients (95.5%) with available data on antibody status following two doses of the Pfizer BioNTech BNT162b2 vaccination had detectable antibody response, whilst this was the case for 97 of 101 patients (96.1%) who received two doses of the Oxford AstraZeneca ChAdOx1 nCoV-19 vaccine. For 12 seronegative patients who received a booster vaccine (third dose), nine seroconverted, while one remained negative and two were not tested. No statistically significant differences were observed with regards to antibody status between those receiving Pfizer BioNTech BNT162b2 and Oxford AstraZeneca ChAdOx1 nCoV-19 vaccines. Sixty-three of 353 patients with two doses of COVID-19 vaccination had breakthrough COVID-19 infection (40 during Delta and 23 during Omicron variant predominance). Of the 40 patients during the delta period, five were admitted into hospital and there were two reported deaths due to COVID-19-related illness. There were no COVID-19 associated hospitalizations or deaths during the Omicron variant predominance. Conclusions: The vast majority of HD patients who received two doses of the Pfizer BioNTech BNT162b2 or Oxford AstraZeneca ChAdOx1 nCoV-19 vaccinations developed detectable antibody responses. Our results support the value of booster vaccination with mRNA-based COVID-19 vaccine in HD patients and highlight the need for ongoing surveillance programmes with rRT-PCR and antibody testing for timely detection of positive cases.

Advances in COVID-19 mRNA vaccine development

To date, the coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has determined 399,600,607 cases and 5,757,562 deaths worldwide. COVID-19 is a serious threat to human health globally. The World Health Organization (WHO) has declared COVID-19 pandemic a major public health emergency. Vaccination is the most effective and economical intervention for controlling the spread of epidemics, and consequently saving lives and protecting the health of the population. Various techniques have been employed in the development of COVID-19 vaccines. Among these, the COVID-19 messenger RNA (mRNA) vaccine has been drawing increasing attention owing to its great application prospects and advantages, which include short development cycle, easy industrialization, simple production process, flexibility to respond to new variants, and the capacity to induce better immune response. This review summarizes current knowledge on the structural characteristics, antigen design strategies, delivery systems, industrialization potential, quality control, latest clinical trials and real-world data of COVID-19 mRNA vaccines as well as mRNA technology. Current challenges and future directions in the development of preventive mRNA vaccines for major infectious diseases are also discussed.

The SARS-CoV-2 Delta variant induces an antibody response largely focused on class 1 and 2 antibody epitopes

Exposure histories to SARS-CoV-2 variants and vaccinations will shape the specificity of antibody responses. To understand the specificity of Delta-elicited antibody immunity, we characterize the polyclonal antibody response elicited by primary or mRNA vaccine-breakthrough Delta infections. Both types of infection elicit a neutralizing antibody response focused heavily on the receptor-binding domain (RBD). We use deep mutational scanning to show that mutations to the RBD's class 1 and class 2 epitopes, including sites 417, 478, and 484-486 often reduce binding of these Delta-elicited antibodies. The anti-Delta antibody response is more similar to that elicited by early 2020 viruses than the Beta variant, with mutations to the class 1 and 2, but not class 3 epitopes, having the largest effects on polyclonal antibody binding. In addition, mutations to the class 1 epitope (e.g., K417N) tend to have larger effects on antibody binding and neutralization in the Delta spike than in the D614G spike, both for vaccine- and Delta-infection-elicited antibodies. These results help elucidate how the antigenic impacts of SARS-CoV-2 mutations depend on exposure history.

COVID-19 breakthrough infections, hospitalizations and mortality in fully vaccinated patients with hematologic malignancies: A clarion call for maintaining mitigation and ramping-up research

There has been limited data presented to characterize and quantify breakthrough SARS-CoV-2 infections, hospitalizations, and mortality in vaccinated patients with hematologic malignancies (HM). We performed a retrospective cohort study of patient electronic health records of 514,413 fully vaccinated patients from 63 healthcare organizations in the US, including 5956 with HM and 508,457 without malignancies during the period from December 2020 to October 2021. The breakthrough SARS-CoV-2 infections in patients with HM steadily increased and reached 67.7 cases per 1000 persons in October 2021. The cumulative risk of breakthrough infections during the period in patients with HM was 13.4%, ranging from 11.0% for acute lymphocytic leukemia to 17.2% and 17.4% for multiple myeloma and chronic myeloid leukemia respectively, all higher than the risk of 4.5% in patients without malignancies (p < 0.001). No significant racial disparities in breakthrough infections were observed. The overall hospitalization risk was 37.8% for patients with HM who had breakthrough infections, significantly higher than 2.2% for those who had no breakthrough infections (hazard ratio or HR: 34.49, 95% CI: 25.93-45.87). The overall mortality risk was 5.7% for patients with HM who had breakthrough infections, significantly higher than the 0.8% for those who had no breakthrough infections (HR: 10.25, 95% CI: 5.94-17.69). In summary, this study shows that among the fully vaccinated population, patients with HM had significantly higher risk for breakthrough infections compared to patients without cancer and that breakthrough infections in patients with HM were associated with significant clinical outcomes including hospitalizations and mortality.

Association of COVID-19 with New-Onset Alzheimer's Disease

An infectious etiology of Alzheimer's disease has been postulated for decades. It remains unknown whether SARS-CoV-2 viral infection is associated with increased risk for Alzheimer's disease. In this retrospective cohort study of 6,245,282 older adults (age ≥65 years) who had medical encounters between 2/2020-5/2021, we show that people with COVID-19 were at significantly increased risk for new diagnosis of Alzheimer's disease within 360 days after the initial COVID-19 diagnosis (hazard ratio or HR:1.69, 95% CI: 1.53-1.72), especially in people age ≥85 years and in women. Our findings call for research to understand the underlying mechanisms and for continuous surveillance of long-term impacts of COVID-19 on Alzheimer's disease.