Risk reduction of severe outcomes in vaccinated COVID-19 cases: an analysis of surveillance data from Estonia, Ireland, Luxembourg and Slovakia, January to November 2021

Marrone, Gaetano; Nicolay, Nathalie; Bundle, Nick; Kärki, Tommi; Spiteri, Gianfranco; Suija, Heleene; Kärblane, Kerstin-Gertrud; Mossong, Joël; Vergison, Anne; Maria, Andrea De; Mečochová, Adriana; Cullen, Gillian; O’Lorcain, P.; Celentano, Lucia Pastore; Derrough, Tarik; Beauté, Julien

doi:10.2807/1560-7917.es.2022.27.7.2200060

Cited by 8 publications

(8 citation statements)

References 7 publications

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“…Our results are largely in agreement with the findings of Moghadas et al, who found a similar significant reduction of adverse outcomes in vaccinated individuals compared to non-vaccinated individuals in the USA [ 18 ]. Similarly, Marrone et al found a reduced risk of severe cases in vaccinated compared to non-vaccinated individuals in some European countries, confirming old age as one of the main risk factors [ 19 , 20 ].…”

Section: Discussionmentioning

confidence: 92%

COVID-19: Relative Risk of Non-Vaccinated to Vaccinated Individuals

et al. 2022

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Following the outbreak of the COVID-19 pandemic, Italy has implemented an extensive vaccination campaign involving individuals above the age of 12, both sexes. The public opinion and the medical community alike questioned the usefulness and efficacy of the vaccines against SARS-CoV-2. The widespread opinion was that the vaccines protected individuals especially against serious conditions which could require intensive care and may lead to the death of the patient rather than against the possibility of infection. In order to quantify the effect of the vaccination campaign, we calculated the relative risks of non-vaccinated and vaccinated individuals for all possible outcomes of the disease: infection, hospitalization, admission to intensive care and death. Relative risk was assessed by means of likelihood ratios, the ratios of the probability of an outcome in non-vaccinated individuals to the probability of the same outcome in vaccinated individuals. Results support the hypothesis that vaccination has an extensive protective effect against both critical conditions and death. Nonetheless, the relative magnitude of the protection in vaccinated individuals compared to those non-vaccinated appears to be higher against the former outcome than the latter, for reasons which need to be investigated further.

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Section: Discussionmentioning

confidence: 92%

COVID-19: Relative Risk of Non-Vaccinated to Vaccinated Individuals

et al. 2022

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“…This study has some limitations. Our results are not estimates of the vaccine effectiveness in preventing hospitalisations and severe disease in the population but among COVID-19 cases, and the vaccine effect in preventing SARS-CoV-2 infections was not considered [ 28 ]. Vaccination coverage varied greatly with age, comorbidity and month, but analyses were adjusted for these variables.…”

Section: Discussionmentioning

confidence: 99%

“…Risk reduction of severe disease a of full vaccination with booster dose vs full vaccination 6 months or more before positive test in COVID-19 cases by age, sex and underlying conditions, Navarre, Spain, 3 January-20 March 2022 (n =28,867) …”

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confidence: 99%

Risk reduction of hospitalisation and severe disease in vaccinated COVID-19 cases during the SARS-CoV-2 variant Omicron BA.1-predominant period, Navarre, Spain, January to March 2022

Martínez-Baz,

Trobajo-Sanmartín,

Miqueleiz

et al. 2023

Eurosurveillance

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Background As COVID-19 vaccine effectiveness against SARS-CoV-2 infection was lower for cases of the Omicron vs the Delta variant, understanding the effect of vaccination in reducing risk of hospitalisation and severe disease among COVID-19 cases is crucial. Aim To evaluate risk reduction of hospitalisation and severe disease in vaccinated COVID-19 cases during the Omicron BA.1-predominant period in Navarre, Spain. Methods A case-to-case comparison included COVID-19 epidemiological surveillance data in adults ≥ 18 years from 3 January–20 March 2022. COVID-19 vaccination status was compared between hospitalised and non-hospitalised cases, and between severe (intensive care unit admission or death) and non-severe cases using logistic regression models. Results Among 58,952 COVID-19 cases, 565 (1.0%) were hospitalised and 156 (0.3%) were severe. The risk of hospitalisation was reduced within the first 6 months after full COVID-19 vaccination (complete primary series) (adjusted odds ratio (aOR): 0.06; 95% CI: 0.04–0.09) and after 6 months (aOR: 0.16; 95% CI: 0.12–0.21; pcomparison < 0.001), as well as after a booster dose (aOR: 0.06: 95% CI: 0.04–0.07). Similarly, the risk of severe disease was reduced (aOR: 0.13, 0.18, and 0.06, respectively). Compared with cases fully vaccinated 6 months or more before a positive test, those who had received a booster dose had lower risk of hospitalisation (aOR: 0.38; 95% CI: 0.28–0.52) and severe disease (aOR: 0.38; 95% CI: 0.21–0.68). Conclusions Full COVID-19 vaccination greatly reduced the risk of hospitalisation and severe outcomes in COVID-19 cases with the Omicron variant, and a booster dose improved this effect in people aged over 65 years.

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“…Such VOCs possess many amino acid substitutions in the spike (S) protein of SARS-CoV-2 that reduce the potency of the neutralizing antibodies that are induced by vaccination and SARS-CoV-2 infection. 5 , 6 Although the vaccines reduce the severity of COVID-19, 7 novel VOCs that escape from the neutralizing antibodies induced by vaccination and infection may continue to emerge.…”

Section: Introductionmentioning

confidence: 99%