Effectiveness of Monovalent mRNA COVID-19 Vaccination in Preventing COVID-19-Associated Invasive Mechanical Ventilation and Death Among Immunocompetent Adults During the Omicron Variant Period - IVY Network, 19 U.S. States, February 1, 2022-January 31, 2023.

As of April 2023, the COVID-19 pandemic has resulted in 1.1 million deaths in the United States, with approximately 75% of deaths occurring among adults aged ≥65 years (1). Data on the durability of protection provided by monovalent mRNA COVID-19 vaccination against critical outcomes of COVID-19 are limited beyond the Omicron BA.1 lineage period (December 26, 2021-March 26, 2022). In this case-control analysis, the effectiveness of 2-4 monovalent mRNA COVID-19 vaccine doses was evaluated against COVID-19-associated invasive mechanical ventilation (IMV) and in-hospital death among immunocompetent adults aged ≥18 years during February 1, 2022-January 31, 2023. Vaccine effectiveness (VE) against IMV and in-hospital death was 62% among adults aged ≥18 years and 69% among those aged ≥65 years. When stratified by time since last dose, VE was 76% at 7-179 days, 54% at 180-364 days, and 56% at ≥365 days. Monovalent mRNA COVID-19 vaccination provided substantial, durable protection against IMV and in-hospital death among adults during the Omicron variant period. All adults should remain up to date with recommended COVID-19 vaccination to prevent critical COVID-19-associated outcomes.

Early Estimates of Bivalent mRNA Vaccine Effectiveness in Preventing COVID-19-Associated Hospitalization Among Immunocompetent Adults Aged ≥65 Years - IVY Network, 18 States, September 8-November 30, 2022.

Monovalent COVID-19 mRNA vaccines, designed against the ancestral strain of SARS-CoV-2, successfully reduced COVID-19-related morbidity and mortality in the United States and globally (1,2). However, vaccine effectiveness (VE) against COVID-19-associated hospitalization has declined over time, likely related to a combination of factors, including waning immunity and, with the emergence of the Omicron variant and its sublineages, immune evasion (3). To address these factors, on September 1, 2022, the Advisory Committee on Immunization Practices recommended a bivalent COVID-19 mRNA booster (bivalent booster) dose, developed against the spike protein from ancestral SARS-CoV-2 and Omicron BA.4/BA.5 sublineages, for persons who had completed at least a primary COVID-19 vaccination series (with or without monovalent booster doses) ≥2 months earlier (4). Data on the effectiveness of a bivalent booster dose against COVID-19 hospitalization in the United States are lacking, including among older adults, who are at highest risk for severe COVID-19-associated illness. During September 8-November 30, 2022, the Investigating Respiratory Viruses in the Acutely Ill (IVY) Network§ assessed effectiveness of a bivalent booster dose received after ≥2 doses of monovalent mRNA vaccine against COVID-19-associated hospitalization among immunocompetent adults aged ≥65 years. When compared with unvaccinated persons, VE of a bivalent booster dose received ≥7 days before illness onset (median = 29 days) against COVID-19-associated hospitalization was 84%. Compared with persons who received ≥2 monovalent-only mRNA vaccine doses, relative VE of a bivalent booster dose was 73%. These early findings show that a bivalent booster dose provided strong protection against COVID-19-associated hospitalization in older adults and additional protection among persons with previous monovalent-only mRNA vaccination. All eligible persons, especially adults aged ≥65 years, should receive a bivalent booster dose to maximize protection against COVID-19 hospitalization this winter season. Additional strategies to prevent respiratory illness, such as masking in indoor public spaces, should also be considered, especially in areas where COVID-19 community levels are high (4,5).

COVID-19-from emerging global threat to ongoing pandemic crisis.

In December 2019, China witnessed the emergence of a novel coronavirus, SARS-CoV-2. Its ability to spread quickly made it a global pandemic. The United States has been greatly affected, with more than 980,000 lives lost so far. Diagnosis is made primarily through nasopharyngeal swab for polymerase chain reaction. Point-of-care testing by antigen is less sensitive and specific and may require polymerase chain reaction confirmation. Management of the COVID-19 patient remains largely supportive. Steroids are now a therapy mainstay if the patient is hypoxic. Direct antivirals, such as nirmatrelvir/ritonavir, remdesivir, or molnupirivir, can be used if certain criteria are met. SARS-CoV-2 is transmitted primarily by inhalation of large droplets, though transmission by aerosolization may occur, particularly via certain procedures. In the hospital setting, use of personal protective equipment for the care of COVID-19 patients has largely remained the same, with full use of gowns, gloves, respirators, and eye protection. Inadequate supply at the start of the pandemic required innovative ways to reprocess and extend the use of personal protective equipment. Three vaccines are now available in the US, all with excellent efficacy against severe disease and hospitalization, though booster doses are needed to bolster waning antibody levels. The possibility of emerging variants continues to remain a threat to control of the pandemic. The leader of the World Health Organization, Dr. Tedros, has stated, "The pandemic will not be over anywhere until it's over everywhere."

2019 novel coronavirus: an emerging global threat.

The coronavirus (CoV) epidemic that began in China in December 2019 follows earlier epidemics of severe acute respiratory syndrome CoV in China and Middle East respiratory syndrome CoV in Saudi Arabia. The full genome of the 2019 novel coronavirus (2019-nCoV) has now been shared, and data have been gathered from several case series. As of February 11, 2020, there have been 45,182 laboratory-confirmed cases, the vast majority in China, with 1115 deaths, for an overall case-fatality rate of 2.5%. Cases have been confirmed in 27 countries. On average, each patient infects 2.2 other people. Symptomatic infection appears to predominantly affect adults, with a 5-day estimated incubation period between infection and symptom onset. The most common presenting symptoms are fever, cough, dyspnea, and myalgias and/or fatigue. All cases reported to date have shown radiographic evidence of pneumonia. 2019-nCoV is diagnosed by real-time reverse transcriptase polymerase chain reaction. Treatment is largely supportive, with regimens including antiviral therapy. Corticosteroids are not routinely recommended. Hand hygiene, prompt identification and isolation of suspect patients, and appropriate use of personal protective equipment are the most reliable methods to contain the epidemic.