Effectiveness of mRNA-1273 against Delta, Mu, and other emerging variants

Abstract

Background: Real-world studies have found high vaccine effectiveness (VE) of mRNA-based COVID-19 vaccines, but reduced VE against the Delta variant and waning protection have been reported, with few studies examining mRNA-1273 variant-specific VE. Methods: We conducted a test-negative case-control study at Kaiser Permanente Southern California. Whole genome sequencing was conducted for SARS-CoV-2 positive specimens collected from 3/1/2021 to 7/27/2021. Test-positive cases were matched 1:5 to test-negative controls on age, sex, race/ethnicity, and specimen collection date. Outcomes included SARS-CoV-2 infection and hospitalization. Exposures were 2 doses or 1 dose of mRNA-1273 ≥14 days prior to specimen collection versus no COVID-19 vaccination. Conditional logistic regression was used to compare odds of vaccination among cases versus controls, adjusting for confounders. VE was calculated as (1-odds ratio)x100%. Results: The study included 8,153 cases and their matched controls. Two-dose VE (95% confidence interval) was 86.7% (84.3-88.7%) against Delta infection, 98.4% (96.9-99.1%) against Alpha, 90.4% (73.9-96.5%) against Mu, 96-98% against other identified variants, and 79.9% (76.9-82.5%) against unidentified variants. VE against Delta declined from 94.1% (90.5-96.3%) 14-60 days after vaccination to 80.0% (70.2-86.6%) 151-180 days after vaccination. Waning was less pronounced for non-Delta variants. VE against Delta was lower among individuals aged ≥65 years (75.2% [59.6-84.8%]) than those aged 18-64 years (87.9% [85.5-89.9%]). VE against Delta hospitalization was 97.6% (92.8-99.2%). One-dose VE was 77.0% (60.7-86.5%) against Delta infection. Conclusions: Two doses of mRNA-1273 were highly effective against all SARS-CoV-2 variants. However, VE against Delta moderately declined with increasing time since vaccination.

Duration of effectiveness of vaccines against SARS-CoV-2 infection and COVID-19 disease: results of a systematic review and meta-regression

“…Three studies were randomised controlled trials 19 , 20 , 21 and 15 were post-introduction observational studies (seven were test-negative design case-control studies, six were retrospective studies, and two were prospective cohort studies; table 1 ). 10 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 Studies were done in Canada (one study), Finland (one study), Israel (one study), Qatar (one study), Spain (one study), Sweden (one study), the UK (two studies), the USA (eight studies), and in addition two multicountry clinical trials were carried out. The Canadian study included separate results for Quebec and British Columbia; therefore, the results for each province were considered separately for this review.…”

“…Ten studies evaluated the vaccine efficacy or effectiveness over time for SARS-CoV-2 infection, among which were 26 vaccine-specific analyses (Pfizer–BioNTech-Comirnaty, n=13; Moderna-mRNA-1273, n=9; Janssen-Ad26.COV2.S, n=2; AstraZeneca-Vaxzevria, n=2; table 1 ). 10 , 22 , 23 , 26 , 28 , 31 , 33 , 34 , 35 Ten vaccine-specific analyses took place in single-variant settings (all delta settings), and 16 in mixed-variant settings. 18 vaccine-specific analyses included people of all ages and eight analyses were done among older people.…”

Booster of mRNA-1273 Strengthens SARS-CoV-2 Omicron Neutralization

“…The Alpha variant approached dominant status by early 2021 and was soon surpassed by the Delta variant, which has dominated the pandemic since mid-2021. Alpha and Delta were modest neutralization escape variants, being 2-3 fold less susceptible than D614G to neutralization by mRNA-1273 vaccine-induced antibodies (5) and having little impact on mRNA-1273 vaccine efficacy (6). Other variants caused transient regional outbreaks but were unable to compete on a global scale.…”

Immune Evasive Effects of SARS-CoV-2 Variants to COVID-19 Emergency Used Vaccines

“…Furthermore, the mRNA-1273 vaccine remained highly effective against Gamma and emerging Delta and Mu variants , and the vaccine efficacies against these variants were 95.5%, 86.7% and 90.4%, respectively. However, the efficacies against these variants gradually decreased with the duration of the post-vaccination time ( 66 ). On the other hand, the vaccine-induced antibodies showed neutralizing activity against four variants, including nCoV/USA_WA1/2020 (line A.1), EHC-083E (line B.1), B.1.1.7, and N501Y ( 95 ), but the neutralization activity against B.1.351 variant was significantly lost ( 96 ).…”