Patients with covid were most contagious on the day of symptom onset.


American and Chinese scientists have calculated that people who come into contact with a sick covid on the day of his symptoms are at the highest risk of infection. The researchers made such a conclusion by tracing the contacts of sick people. Work published v JAMA Internal Medicine.

Patients with coronavirus secrete a different number of viral particles depending on the period of illness: over time, infected cells are released smaller viral RNA. Recently scientists identifiedthat the patient is most contagious in the first days after the onset of symptoms, but there were few participants in the study, and more studies on more people are needed to confirm the conclusions of the authors of the work.

US and Chinese scientists led by Ye Shen of the University of Georgia increased the sample size to test their colleagues’ findings. The study included 8852 people who at various times had contact with 730 patients with coronavirus. These people were monitored over a two-week period and periodically (the authors did not indicate the exact time interval) took PCR tests from them for coronavirus.

It turned out that the greatest risk of contracting covid was in people who communicated with the patient one to two days before the onset of symptoms and in the next three days, and the peak of infectiousness occurred on the day of the onset of symptoms (relative risk, ARR = 1.3). Moreover, the more severe the coronavirus infection was in a patient, the less likely a person infected from him was to transfer the infection asymptomatically.

The researchers conclude that most likely, when infected with covid, the severity of the disease depends on the dose of viral particles obtained, and the patient releases their maximum on the day of the onset of symptoms.

Coronavirus RNA persists on objects for a long time. So American researchers found RNA of coronavirus in the house of those who had recovered a month after their symptoms disappeared. At the same time, it is not known for sure whether the coronavirus can infect people from the surface of household items.

Anastasia Kuznetsova-Fantoni

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