The infectivity of the new coronavirus was found to be 'strongest before the onset', and half of the infected people may have the virus transmitted from people before the onset

Until now, it was known that the novel coronavirus infection (COVID-19) may infect people with the virus when there are no symptoms or even before the symptoms appear. Furthermore, a study that traced the case where the new coronavirus (SARS-CoV-2) actually transmitted from person to person was found to be 'SARS-CoV-2 is the most infectious just before symptoms appear'. It was.

Temporal dynamics in viral shedding and transmissibility of COVID-19 | Nature Medicine

COVID-19 may be most contagious one to two days before symptoms appear | Science News

Nearly Half Of COVID-19 Infections Occurred Before Symptoms: Study | Asian Scientist Magazine | Science, technology and medical news updates from Asia

Eric Lau et al.'S research team at the School of Public Health, University of Hong Kong, set out to test the number of viruses shed by people infected with SARS-CoV-2 between January 21 and February 14, 2020 in China. We conducted a test for 94 COVID-19 patients admitted to Guangzhou City Eighth People's Hospital. As a result, it was found that the number of SARS-CoV-2 detected in COVID-19 patients peaked immediately after the onset and then decreased for about 21 days.

The following is a graph showing that the number of days after the horizontal axis onset, the vertical axis PCR is one of the test RT-PCR Number of SARS-CoV-2 detected in the examination.

Furthermore, the research team analyzed 77 cases of 'SARS-CoV-2 primary infection and secondary infection known to be infected by that person' from China and abroad. We simulated the timing of SARS-CoV-2 transmission from person to person, assuming an average latency of 5.2 days for SARS-CoV-2.

The results are shown in the graph below, where the horizontal axis is the time axis with the day of COVID-19 onset as 0, and the vertical axis is the virus infectivity. Simulation results revealed that SARS-CoV-2 infectivity rapidly increased 2.3 days before the onset of COVID-19 and peaked 0.7 days before the onset of COVID-19. Infectiousness rapidly declines within 7 days after the onset of COVID-19, and the percentage of secondary infections from SARS-CoV-2 infected before the onset is 44%, which is almost half. I understand.

According to the research team, the characteristic of SARS-CoV-2 that the infectivity peaks before the onset is that the infectivity of the SARS coronavirus that spread in 2003 became maximum 7 to 8 days after the onset. It is in contrast.

From the results of these studies, the research team said, `` Because pre-onset infections account for a considerable proportion, we would like to implement hand washing and social distance expansion strategies in the absence of COVID-19 therapeutic agents and SARS-CoV-2 vaccines. Thorough implementation will be the cornerstone of measures. '

in Science, Posted by log1l_ks