The incubation period from infection to symptoms or a first positive COVID-19 test has decreased as the coronavirus has evolved, dropping from 5 days to 3.5 days, according to a new study published in JAMA Network Open.

With the Alpha variant, the incubation period was about jual alat suling minyak atsiri 5 days, which fell to 4.5 for Beta, 4.41 for Delta, and 3.42 for Omicron.

“Knowledge of the disease’s incubation period is of great significance for case definition, management of emerging threats, estimation of the duration of follow-up for contact tracing and secondary case detection, and the establishment of public health programs aimed at reducing local transmission,” the study authors wrote.

Researchers at Peking University and Tsinghua University in China analyzed 142 studies published between December 2019 and February 2022. The studies included data about more than 8,100 COVID-19 patients.

Most of the studies (65.5%) were done between January and March 2020, and 76.1% were done in China. The remaining studies came from multiple countries or were based in Australia, France, India, Japan, Singapore, South Korea, and Vietnam.

About 84% of the studies included patients infected with the wild-type (or non-mutated) COVID strain, while 3.5% included patients infected with multiple strains, and 7.7% involved unknown strains.

Among the studies, 45 were considered to have strong evidence, 82 were moderate, and 15 were weak.