Introduction: Despite representing only 3% of the US population, immunocompromised (IC) individuals account for nearly half of the COVID-19 breakthrough hospitalizations. IC individuals generate a lower immune response after vaccination in general, and the US CDC recommended a third dose of either mRNA-1273 or BNT162b2 COVID-19 vaccines as part of their primary series. Influenza vaccine trials have shown that increasing dosage could improve effectiveness in IC populations. The objective of this systematic literature review and pairwise meta-analysis was to evaluate the clinical effectiveness of mRNA-1273 (50 or 100 mcg/dose) vs BNT162b2 (30 mcg/dose) in IC populations using the GRADE framework.Methods: The systematic literature search was conducted in the World Health Organization COVID-19 Research Database. Studies were included in the pairwise meta-analysis if they reported comparisons of mRNA-1273 and BNT162b2 in IC individuals ≥18 years of age; outcomes of interest were symptomatic, laboratory-confirmed SARS-CoV-2 infection, SARS-CoV-2 infection, severe SARS-CoV-2 infection, hospitalization due to COVID-19, and mortality due to COVID-19. Risk ratios (RR) were pooled across studies using random-effects meta-analysis models. Outcomes were also analyzed in subgroups of patients with cancer, autoimmune disease, and solid organ transplant. Risk of bias was assessed using the Newcastle-Ottawa Scale for observational studies. Evidence was evaluated using the GRADE framework.Results: Overall, 17 studies were included in the pairwise meta-analysis. Compared with BNT162b2, mRNA-1273 was associated with significantly reduced risk of SARS-CoV-2 infection (RR, 0.85 [95% CI, 0.75–0.97]; P=0.0151; I² = 67.7%), severe SARS-CoV-2 infection (RR, 0.85 [95% CI, 0.77–0.93]; P=0.0009; I² = 0%), COVID-19–associated hospitalization (RR, 0.88 [95% CI, 0.79–0.97]; P<0.0001; I² = 0%), and COVID-19–associated mortality (RR, 0.63 [95% CI, 0.44–0.90]; P=0.0119; I² = 0%) in IC populations. Results were consistent across subgroups. Because of sample size limitations, relative effectiveness of COVID-19 mRNA vaccines in IC populations cannot be studied in randomized trials. Based on nonrandomized studies, evidence certainty among comparisons was type 3 (low) and 4 (very low), reflecting potential biases in observational studies.Conclusion: This GRADE meta-analysis based on a large number of consistent observational studies showed that the mRNA-1273 COVID-19 vaccine is associated with improved clinical effectiveness in IC populations compared with BNT162b2.

The emergence of Omicron variants coincided with declining vaccine-induced protection against SARS-CoV-2. Two bivalent mRNA vaccines, mRNA-1273.222 (Moderna) and BNT162b2 Bivalent (Pfizer-BioNTech), were developed to provide greater protection against the predominate circulating variants by including mRNA that encodes both the ancestral (original) strain and BA.4/BA.5. We estimated their relative vaccine effectiveness (rVE) in preventing COVID-19-related outcomes in the US using a nationwide dataset linking primary care electronic health records and pharmacy/medical claims data. The study population (aged ≥18 years) received either vaccine between 31 August 2022 and 28 February 2023. We used propensity score weighting to adjust for baseline differences between groups. We estimated the rVE against COVID-19-related hospitalizations (primary outcome) and outpatient visits (secondary) for 1,034,538 mRNA-1273.222 and 1,670,666 BNT162b2 Bivalent vaccine recipients, with an adjusted rVE of 9.8% (95% confidence interval: 2.6–16.4%) and 5.1% (95% CI: 3.2–6.9%), respectively, for mRNA-1273.222 versus BNT162b2 Bivalent. The incremental relative effectiveness was greater among adults ≥ 65; the rVE against COVID-19-related hospitalizations and outpatient visits in these patients was 13.5% (95% CI: 5.5–20.8%) and 10.7% (8.2–13.1%), respectively. Overall, we found greater effectiveness of mRNA-1273.222 compared with the BNT162b2 Bivalent vaccine in preventing COVID-19-related hospitalizations and outpatient visits, with increased benefits in older adults.

To assess the potential clinical impact and cost-effectiveness of COVID-19 mRNA vaccines updated for fall 2023 in adults ≥18 years over a 1-year analytic time horizon (September 2023-August 2024). A compartmental Susceptible-Exposed-Infected-Recovered model was updated to reflect COVID-19 cases in summer 2023. The numbers of symptomatic infections, COVID-19-related hospitalizations and deaths, and costs and quality-adjusted life-years (QALYs) gained were calculated using a decision tree model. The incremental cost-effectiveness ratio (ICER) of a Moderna updated mRNA fall 2023 vaccine (Moderna Fall Campaign) was compared to no additional vaccination. Potential differences between the Moderna and the Pfizer-BioNTech fall 2023 vaccines were also examined. Base case results suggest that the Moderna Fall Campaign would decrease the expected 64.2 million symptomatic infections by 7.2 million (11%) to 57.0 million. COVID-19-related hospitalizations and deaths are expected to decline by 343,000 (-29%) and 50,500 (-33%), respectively. The Moderna Fall Campaign would increase QALYs by 740,880 and healthcare costs by $5.7 billion relative to no vaccine, yielding an ICER of $7700 per QALY gained. Using a societal cost perspective, the ICER is $2100. Sensitivity analyses suggest that vaccine effectiveness, COVID-19 incidence, hospitalization rates, and costs drive cost-effectiveness. With a relative vaccine effectiveness of 5.1% for infection and 9.8% for hospitalization for the Moderna vaccine versus the Pfizer-BioNTech vaccine, use of the Moderna vaccine is expected to prevent 24,000 more hospitalizations and 3300 more deaths than the Pfizer-BioNTech vaccine. As COVID-19 becomes endemic, future incidence, including patterns of infection, are highly uncertain. The effectiveness of fall 2023 vaccines is unknown, and it is unclear when a new variant that evades natural or vaccine immunity will emerge. Despite these limitations, our model predicts the Moderna Fall Campaign vaccine is highly cost-effective across all sensitivity analyses.

Few head-to-head comparisons have been performed on the real-world effectiveness of COVID-19 booster vaccines. We evaluated the relative effectiveness (rVE) of a primary series of mRNA-1273 versus BNT162b2 and Ad26.COV2.S and a homologous mRNA booster against any medically-attended, outpatient, and hospitalized COVID-19. A dataset linking primary care electronic medical records with medical claims data was used for this retrospective cohort study of US patients ≥18 years vaccinated with a primary series between February and October 2021 (Part 1) and a homologous mRNA booster between October 2021 and January 2022 (Part 2). Adjusted hazard ratios (HR) were derived from 1:1 matching adjusted across potential covariates. rVE was (1-HR_adjusted) x 100. Additional analysis was performed across regions and age groups. Following adjustment, Part 1 rVE for mRNA-1273 versus BNT162b2 was 23% (95% CI: 22%–25%), 23% (22%–25%), and 19% (14%–24%) whilst the rVE for mRNA-1273 versus Ad26.COV2.S was 50% (48%–51%), 50% (48%–52%), and 57% (53%–61%) against any medically-attended, outpatient, and hospitalized COVID-19, respectively. The adjusted rVE in Part 2 for mRNA-1273 versus BNT162b2 was 14% (10%–18%), 13% (8%–17%), and 19% (1%–34%) against any medically-attended, outpatient, and hospitalized COVID-19, respectively. rVE against medically-attended COVID-19 was higher in adults ≥65 years (35%; 24%–47%) than those 18–64 years (13%; 9%–17%) after the booster. In this study, mRNA-1273 was more effective than BNT162b2 or Ad26.COV2.S following primary series during a Delta-dominant period, and than BNT162b2 as a booster during an Omicron-dominant period.

Approximately 10–20% of individuals suffering from COVID-19 develop prolonged symptoms known as long COVID or post-COVID condition (LC). This review aimed to assess healthcare resource use (HCRU) and healthcare costs associated with LC. Because LC is not clearly defined and often remains undiagnosed, studies reporting on long-term follow-up of individuals with a COVID-19 diagnosis were also included. Among the 41 publications included, 36 reported on HCRU and 16 on costs. Individuals with LC had significantly elevated HCRU and healthcare costs vs. controls without a COVID-19 diagnosis over ≥15 months, with a 7.6–13.1% increase in total healthcare costs per person per month as assessed by difference-in-difference analysis. Among studies that did not specifically refer to LC, having a COVID-19 diagnosis was associated with a significant 4–10% increase in long-term total HCRU over 6–8 months and a 1.3- to 2.9-fold relative increase in total healthcare costs over 6 months. Due to the heterogeneity of the included studies, high-quality evidence is needed to better understand the economic burden of LC. In the absence of effective treatments, prioritizing the prevention of acute COVID-19, e.g., through vaccination, may be crucial for preventing LC and the associated long-term HCRU and medical spending.

Immunocompromised (IC) patients mount poor immune responses to vaccination. Higher-dose coronavirus disease 2019 (COVID-19) vaccines may offer increased immunogenicity. A pairwise meta-analysis of 98 studies reporting comparisons of mRNA-1273 (50 or 100 mcg/dose) and BNT162b2 (30 mcg/dose) in IC adults was performed. Outcomes were seroconversion, total and neutralizing antibody titers, and cellular immune responses. mRNA-1273 was associated with a significantly higher seroconversion likelihood [relative risk, 1.11 (95% CI, 1.08, 1.14); P < 0.0001; I² = 66.8%] and higher total antibody titers [relative increase, 50.45% (95% CI, 34.63%, 66.28%); P < 0.0001; I² = 89.5%] versus BNT162b2. mRNA-1273 elicited higher but statistically nonsignificant relative increases in neutralizing antibody titers and cellular immune responses versus BNT162b2. Higher-dose mRNA-1273 had increased immunogenicity versus BNT162b2 in IC patients.