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MMWR - Morbidity & Mortality Weekly Report ; 71(48):1526-1530, 2022.
Article in English | MEDLINE | ID: covidwho-2145605


On September 1, 2022, bivalent COVID-19 mRNA vaccines, composed of components from the SARS-CoV-2 ancestral and Omicron BA.4/BA.5 strains, were recommended by the Advisory Committee on Immunization Practices (ACIP) to address reduced effectiveness of COVID-19 monovalent vaccines during SARS-CoV-2 Omicron variant predominance (1). Initial recommendations included persons aged >=12 years (Pfizer-BioNTech) and >=18 years (Moderna) who had completed at least a primary series of any Food and Drug Administration-authorized or -approved monovalent vaccine >=2 months earlier (1). On October 12, 2022, the recommendation was expanded to include children aged 5-11 years. At the time of recommendation, immunogenicity data were available from clinical trials of bivalent vaccines composed of ancestral and Omicron BA.1 strains;however, no clinical efficacy data were available. In this study, effectiveness of the bivalent (Omicron BA.4/BA.5-containing) booster formulation against symptomatic SARS-CoV-2 infection was examined using data from the Increasing Community Access to Testing (ICATT) national SARS-CoV-2 testing program.* During September 14-November 11, 2022, a total of 360,626 nucleic acid amplification tests (NAATs) performed at 9,995 retail pharmacies for adults aged >=18 years, who reported symptoms consistent with COVID-19 at the time of testing and no immunocompromising conditions, were included in the analysis. Relative vaccine effectiveness (rVE) of a bivalent booster dose compared with that of >=2 monovalent vaccine doses among persons for whom 2-3 months and >=8 months had elapsed since last monovalent dose was 30% and 56% among persons aged 18-49 years, 31% and 48% among persons aged 50-64 years, and 28% and 43% among persons aged >=65 years, respectively. Bivalent mRNA booster doses provide additional protection against symptomatic SARS-CoV-2 in immunocompetent persons who previously received monovalent vaccine only, with relative benefits increasing with time since receipt of the most recent monovalent vaccine dose. Staying up to date with COVID-19 vaccination, including getting a bivalent booster dose when eligible, is critical to maximizing protection against COVID-19 (1).

Morbidity and Mortality Weekly Report ; 71(7):255-263, 2022.
Article in English | GIM | ID: covidwho-1812722


What is already known about this topic? Protection against COVID-19 after 2 doses of mRNA vaccine wanes, but little is known about durability of protection after 3 doses. What is added by this report? Vaccine effectiveness (VE) against COVID-19-associated emergency department/urgent care (ED/UC) visits and hospitalizations was higher after the third dose than after the second dose but waned with time since vaccination. During the Omicron-predominant period, VE against COVID-19-associated ED/UC visits and hospitalizations was 87% and 91%, respectively, during the 2 months after a third dose and decreased to 66% and 78% by the fourth month after a third dose. Protection against hospitalizations exceeded that against ED/UC visits. What are the implications for public health practice? All eligible persons should remain up to date with recommended COVID-19 vaccinations to best protect against COVID-19-associated hospitalizations and ED/UC visits.

Mmwr-Morbidity and Mortality Weekly Report ; 70(34):1163-1166, 2021.
Article in English | Web of Science | ID: covidwho-1396228


What is already known about this topic? Early observational studies among nursing home residents showed mRNA vaccines to be 53% to 92% effective against SARS-CoV-2 infection. What is added by this report? Two doses of mRNA vaccines were 74.7% effective against infection among nursing home residents early in the vaccination program (March-May 2021). During June-July 2021, when B.1.617.2 (Delta) variant circulation predominated, effectiveness declined significantly to 53.1%. What are the implications for public health practice? Multicomponent COVID-19 prevention strategies, including vaccination of nursing home staff members, residents, and visitors, are critical. An additional dose of COVID-19 vaccine might be considered for nursing home and long-term care facility residents to optimize a protective immune response.