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Boosters and time from the last anti-COVID-19 vaccine dose: lead public health choices by real-time epidemiological assessment.
Russo, Antonio Giampiero; Murtas, Rossella; Tunesi, Sara; Decarli, Adriano; Bergamaschi, Walter.
  • Russo AG; UOC Epidemiology Unit, Agency for Health Protection of the Metropolitan Area of Milan (Italy); agrusso@ats-milano.it.
  • Murtas R; UOC Epidemiology Unit, Agency for Health Protection of the Metropolitan Area of Milan (Italy).
  • Tunesi S; UOC Epidemiology Unit, Agency for Health Protection of the Metropolitan Area of Milan (Italy).
  • Decarli A; UOC Epidemiology Unit, Agency for Health Protection of the Metropolitan Area of Milan (Italy).
  • Bergamaschi W; General Directorate, Agency for Health Protection of the Metropolitan Area of Milan (Italy).
Epidemiol Prev ; 46(1-2): 34-46, 2022.
Article in English | MEDLINE | ID: covidwho-1771985
ABSTRACT

BACKGROUND:

the levels of anti-SARS-CoV-2 antibodies after the second vaccine dose decline in the following months; the administration of an additional vaccine dose (booster) is able to restore the immune system in the short period significantly reducing the risk of a severe disease. In the winter of 2021, a new particularly infectious variant caused the urgent need to increase the coverage of the booster dose.

OBJECTIVES:

to present, using real data, an evaluation of the efficacy of the booster dose in reducing the severe disease of SARS-CoV-2 infection in terms of hospital admissions, intensive care and death from all causes.

DESIGN:

descriptive study of vaccine adherence; associative study of the factors linked with adherence of vaccination and COVID-19 symptoms; associative study of vaccine effectiveness against hospital admission and mortality. SETTING AND

PARTICIPANTS:

population-based study in the Milan and Lodi provinces (Lombardy Region, Northern Italy) with subjects aged >=19 years alive at 01.10.2021, not residing in a nursery home, followed up to 31.12.2021. MAIN OUTCOME

MEASURES:

COVID-19 symptoms, hospitalization for COVID-19, intensive care hospitalization, and all-cause mortality in the period 01.10.2021-31.12.2021.

RESULTS:

the cohort included 2,936,193 patients at 01.10.2021 at the end of the follow-up period (31.12.2021), 378,616 (12.9%) had no vaccine, 128,879 (4.3%) had only 1 dose, 412,227 (14.0%) had a 2nd dose given since less than 4 months, 725. 806 (25%) had a 2nd dose given since 4-7 months, 74,152 (2.5%) had a 2nd dose given since 7+ months, 62,614 (2.1%) had a 2nd dose and have had the disease, and 1,153,899 (39.3%) received the booster. In the study period (01.10.2021-31.12.2021), characterized by a very high prevalence of the omicron variant, 121,620 cases (antigenic/molecular buffer positive), 3,661 hospitalizations for COVID-19, 162 ICU hospitalizations, and 7,508 deaths from all causes were identified. Compared to unvaccinated people, subjects who had the booster dose had half the risk of being symptomatic, in particular for asthenia, muscle pain, and dyspnoea which are the most commons COVID-19 symptoms. In comparison with the subjects who had the booster dose, the unvaccinated had a 10-fold risk of hospitalization for COVID-19, a 9-fold risk of intensive care, and a 3-fold risk of dying.

CONCLUSIONS:

this work highlights the vaccination efficacy in reducing serious adverse events for those who undergo the booster and the need to implement specific engagement policies to bring to a booster those who had taken the second dose since the longest time.
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Full text: Available Collection: International databases Database: MEDLINE Main subject: Public Health / COVID-19 Type of study: Cohort study / Experimental Studies / Observational study / Prognostic study Topics: Vaccines / Variants Limits: Adult / Humans / Young adult Country/Region as subject: Europa Language: English Journal: Epidemiol Prev Journal subject: Epidemiology Year: 2022 Document Type: Article

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Full text: Available Collection: International databases Database: MEDLINE Main subject: Public Health / COVID-19 Type of study: Cohort study / Experimental Studies / Observational study / Prognostic study Topics: Vaccines / Variants Limits: Adult / Humans / Young adult Country/Region as subject: Europa Language: English Journal: Epidemiol Prev Journal subject: Epidemiology Year: 2022 Document Type: Article