Age-dependent effects on infectivity and susceptibility to SARS-CoV-2 infection: results from nationwide contact tracing data in Greece.
Infect Dis (Lond)
; 54(3): 186-195, 2022 03.
Article
in English
| MEDLINE | ID: covidwho-1505665
ABSTRACT
BACKGROUND:
Understanding the factors that affect the transmissibility of SARS-CoV-2 remains important to keep transmission low and maximize the health benefits of vaccination. We assessed the factors associated with the transmissibility of SARS-CoV-2 based on contact tracing data.METHODS:
From 1 October to 9 December 2020, 29,385 laboratory-confirmed SARS-CoV-2 cases (index cases, i.e. the first identified laboratory-confirmed cases or with the earliest symptom onset in a setting) and 64,608 traced contacts were identified in Greece. We assessed the prevalence of symptoms in cases, calculated secondary attack rates and assessed factors associated with infectivity and susceptibility to infection.RESULTS:
There were 11,232 contacts secondarily infected (secondary attack rate 17.4%, 95% CI17.0-17.8). Contacts aged 0-11 and 12-17 years were less susceptible to infection than adults 65 years or older (odds ratio (OR) [95% CI] 0.28 [0.26-0.32] and 0.44 [0.40-0.49], respectively). Index cases aged 65 years or older were more likely to infect their contacts than other adults or children/adolescents. The odds of infection [95% CI] were higher in contacts exposed within the household (1.71 [1.59-1.85] vs. other) and in cases with cough (1.17 [1.11-1.25] vs. no cough). There was an interaction between the age of the index and the age of the contact with contacts 65 years or older having a higher probability of infection when exposed to cases of similar age than to children.CONCLUSIONS:
Our findings highlight the role of age and age mixing in infectivity and susceptibility to SARS-CoV-2 infection. Precautions are necessary for individuals 65 or older as they have higher infectivity and susceptibility in contact with their peers.Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Contact Tracing
/
COVID-19
Type of study:
Experimental Studies
/
Observational study
/
Prognostic study
Topics:
Vaccines
Limits:
Adolescent
/
Adult
/
Aged
/
Child
/
Humans
Country/Region as subject:
Europa
Language:
English
Journal:
Infect Dis (Lond)
Year:
2022
Document Type:
Article
Affiliation country:
23744235.2021.1995627
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