The symptoms caused by a Covid-19 infection would make patients four times more contagious than those, contaminated, who show no symptoms.
- The risk of contagion is 3.85 times higher in contact with a symptomatic person compared to an asymptomatic patient
- These results confirm another study according to which the contacts of a symptomatic patient have a 12.8% chance of being contaminated compared to 3.5% for those of an asymptomatic patient.
Having or not having symptoms of Covid-19 is not without consequence. A study conducted in Singapore reveals that people who show symptoms are almost four times more contagious than those who do not have symptoms. The results were published on December 18 in the journal The Lancet.
3.85 times higher risk for symptomatic contact cases
The researchers based their study on the analysis of screening data collected in Singapore where there is significant tracing of contact cases. Frequent tests are carried out with the workers and if they prove positive, all the contact cases of the patient are tested and quarantined in the event of positivity. The authors of the study focused their research on isolated contact cases between 1er August and October 11 and separated contact cases of symptomatic people from asymptomatic patients.
A total of 628 people with Covid-19 were included in this analysis. Then 3,790 people were contact cases and were quarantined. A total of 89 of them (or 2%) contracted the virus. Of these, 50 were contact cases of an asymptomatic person, or 56%, and 39 (44%) were contact cases of a person with symptoms. The researchers then revealed that the risk of contagion is 3.85 times higher for contact cases of a symptomatic person compared to an asymptomatic infected person. “Our results suggest that people with asymptomatic Covid-19 are infectious but may be less infectious than symptomatic cases”, wrote the researchers.
Guiding public policies
This work confirms the conclusions of a previous study carried out by British researchers from theImperial College London. According to these, the contact cases of a symptomatic patient have a 12.8% chance of being contaminated compared to 3.5% for the contacts of an asymptomatic patient and 9% for pre-symptomatic patients, it is i.e. a Covid-19 patient whose symptoms have not yet appeared. Good news for the next vaccination campaign. The vaccine developed by Pfizer shows an effectiveness of 95% “to prevent mild to moderate symptomatic forms of Covid-19”.
The authors of the new study believe that these results must be taken into account to carry out the fight against the epidemic. “These results suggest that where resources permit, contact tracing should proactively seek out people with asymptomatic Covid-19 as they can transmit disease and will need to be contained if a national policy goal is to minimize cases and transmission. transmissionthey write. However, if resources are limited, it may be more effective to reduce population-level transmission by focusing contact tracing on symptomatic people who are easy to identify..”
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