August 23, 2022: The incubation period from infection to symptoms or a first positive COVID-19 test has decreased as the coronavirus has evolved from five days to 3. 5 days, according to a new one published in JAMA Network Open.
With the Alpha variant, incubation was about five days, which dropped to 4. 5 for Beta, 4. 41 for Delta and 3. 42 for Omicron.
“Knowledge of the disease incubation era is of great importance for case definition, emerging threat management, estimation of follow-up duration for contact tracing and secondary case detection, and implementation of public fitness systems for local transmission,” the study authors wrote. study.
Researchers from Peking University and Tsinghua University in China analyzed 142 studies between December 2019 and February 2022. The studies included knowledge about more than 8100 covid-19 patients.
Most of the studies (65. 5%) were conducted between January and March 2020, and 76. 1% were conducted in China. The other studies came from several countries or were conducted in Australia, France, India, Japan, Singapore, South Korea and Vietnam.
About 84% of the studies included patients inflamed with the wild-type (or unmutated) COVID strain, while 3. 5% included patients inflamed with strains and 7. 7% referred to unknown strains.
Of the studies, forty-five had to have strong evidence, 82 moderate and 15 weak.
Overall, the average incubation time for all variants is 6. 57 days, with a range of 1. 8 to 18. 87 days. In other people over the age of 60, the average incubation time is 7. 43 days. In children, the average incubation time is 8. 82 days.
Incubation was about 7 days in other people with mild or moderate disease and 6. 7 days in those with severe illness.
Average incubation times decreased over time with each new variant, the study authors found. For Alpha, which had a study with 6,374 patients, the incubation period was about five days. For Beta, which had a study with 10 patients, the incubation period was four. . five days. For Delta, which conducted six studies with 2368 patients, the incubation period was 4. 41 days. For Omicron, which conducted five studies with 829 patients, the incubation period was 3. 42 days.
“The effects of this study suggest that SARS-CoV-2 has evolved and mutated frequently during the COVID-19 pandemic, generating variants with accelerated transmission and virulence,” the study authors wrote. “Identifying the incubation stage of other variants is a key thing in uncovering the era of isolation. “
COVID-19 appears to have a longer incubation time than other viral respiratory infections, they noted, adding human coronavirus or respiratory tract infection (3. 2 days); influenza A (1. 43 to 1. 64 days); parainfluenza or bronchitis (2. 6 days); breathing of syncytial virus, or RSV (4. 4 days); rhinovirus, or bloodless (1. 4 days); and severe acute respiratory syndrome, or SARS (4 days).
Two weeks ago, the CDC issued rules stating that close contacts of COVID-19 patients no longer want to be quarantined. Instead, they wear a high-quality mask for 10 days and get tested five days after exposure. Other infected people self-isolate for at least five days after a positive test.
But assuming covid-19’s incubation period varies from 1 to 14 days, some countries and the World Health Organization continue to propose isolating close contacts for 14 days, the study authors wrote.
“With the shortening of the incubation era of the new variants, the isolation era can be adjusted to lessen the strain on the fitness system,” they said.
JAMA Network Open: “Era of INCUBATION OF COVID-19 THROUGH EXCLUSIVE STRAINS OF SARS-CoV-2. “
CDC: “Cdc is simplifying COVID-19 rules to help the public improve and perceive their risk. “
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