In a recent Morbidity and Mortality Weekly Report (MMWR) published on america Center for Disease Control and Prevention (US-CDC) website, researchers evaluated the sturdiness of protection conferred by monovalent messenger ribonucleic acid (mRNA) coronavirus disease 2019 (COVID-19) vaccines against invasive mechanical ventilation (IMV) and in-hospital death in the course of the period of the predominance of Omicron, i.e., between February 1, 2022, and January 31, 2023.

Study: Effectiveness of Monovalent mRNA COVID-19 Vaccination in Stopping COVID-19–Associated Invasive Mechanical Ventilation and Death Amongst Immunocompetent Adults In the course of the Omicron Variant Period — IVY Network, 19 U.S. States, February 1, 2022–January 31, 2023. Image Credit: wan wei / Shutterstock

Background

Studies have shown that monovalent mRNA COVID-19 vaccines prevented critical outcomes, including COVID-19-related hospitalization, IMV, and death, during predominance eras of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) early variants of concerns (VOCs), Alpha, Delta, and early Omicron variants.

For the reason that starting of the pandemic, over 1.13 million COVID-19–related deaths have occurred in america, with most amongst patients aged ≥65 years. Authorities advisable a bivalent mRNA booster for all individuals who had accomplished a primary COVID-19 vaccination series from September 1, 2022, onward and were at the next risk of progression to severe disease. Nonetheless, bivalent vaccination uptake remained low amongst adults aged ≥18 years, i.e., only 20%, and 42% amongst adults aged ≥65 years. The remaining adults only received monovalent mRNA vaccines.

Thus, data on the sturdiness of protection conferred by monovalent mRNA vaccines against critical COVID-19 outcomes is significant. Nonetheless, there is restricted data on vaccine effectiveness (VE) of monovalent mRNA vaccines beyond the Omicron BA.1 lineage period, i.e., between December 26, 2021, and March 26, 2022. VE against critical outcomes is crucial to tell revaccination intervals in future COVID-19 vaccination policies.

Concerning the study

In the current case-control evaluation, researchers recruited immunocompetent adults aged ≥18 between February 1, 2022, and January 31, 2023, using the Investigating Respiratory Viruses within the Acutely Ailing (IVY) network data to measure the VE of mRNA-based monovalent COVID-19 vaccines against COVID-19–related in-hospital death and IMV.

They collected demographic and clinical patient data through electronic health record (EHR) review, or patient/proxy interview, including IMV receipt and in-hospital death inside 28 days of hospital admission.

The researchers used logistic regression to compute VE against IMV and in-hospital mortality as (1 − adjusted odds ratio [aOR]) x 100%; moreover, they compared the percentages of monovalent mRNA vaccine against unvaccinated COVID-19 cases and control patients. The study model accounted for the U.S. Department of Health and Human Services region, age, gender, calendar time, and self-reported ethnicity/race.

The team stratified study results by age group, time elapsed because the last vaccine dose, and variety of vaccine doses taken. They considered various VE estimates with 95% Confidence Intervals (CIs) statistically significant. This study adhered to the CDC policy and applicable federal laws.

Study findings

The variety of enrollees with IMV or in-hospital mortality within the IVY Network between February 1, 2022, and January 31, 2023, was 6,354; nonetheless, the ultimate evaluation sample set had only 70% of 6354, i.e., 4,421 individuals, of which 362 were cases, and 4,059 were controls. The common age of all included patients was 64 years. Notably, ~91% of COVID-19 patients had a number of persistent health issues, and 20% had experienced COVID-19 at the very least once.

Furthermore, 146, 216, 293, and 156 of 362 COVID-19 case-patients who received IMV or suffered in-hospital death were unvaccinated, monovalent-vaccinated, received IMV, and died inside 28 days of hospital admission, respectively. Of 4,059 controls, 979 (24%) and 3080 (76%) were unvaccinated and monovalent-vaccinated, respectively. Amongst monovalent vaccine recipients, the typical time lapsed from vaccine receipt to illness onset was 248 days.

VE of two to 4 doses of monovalent mRNA vaccine against IMV and in-hospital mortality was 62% amongst adults aged ≥18 years and 57% and 69% amongst patients aged 18–64 years and ≥65 years, respectively. Stratifying by time because the last dose yielded VE of 76%, 54%, and 56% at seven to 179 days, 180 to 364 days, and ≥12 months, respectively.

Overall, monovalent mRNA vaccines showed a 76% efficacy in stopping COVID-19–related IMV and death as much as six months after the last dose and as much as 56% efficacy between one to 2 years. Thus, the authors advisable that each one eligible adults take COVID-19 vaccines to forestall critical outcomes of COVID-19, akin to IMV.

Conclusions

The present evaluation reported VE for monovalent mRNA COVID-19 vaccine against IMV and in-hospital death for 12 months in the course of the Omicron VOC era. Its results suggested that protection against IMV and death after six months from receipt of the last dose waned substantially but still remained clinically significant and offered durable immune protection for over 12 months.

In stratified subanalyses of this study, VE correlated more with time elapsed because the last dose than the variety of vaccine doses received. Overall, these findings reinstate the importance of staying up so far with COVID-19 vaccination to forestall critical outcomes of COVID-19, including additional bivalent mRNA booster shots for people at the very best risk of progression to severe disease.