Transmission of Covid-19 may have begun in November

Given the emergence of agents with the capacity to cause diseases in humans, such as the new coronavirus, the Covid-19, scientists from all over the world have begun to work hard on the search for answers on the behavior of the pathogen. The process is similar to assembling a jigsaw puzzle: at every new research, an increasingly robust set of data takes form, contributing to clarify important characteristics that are crucial to create an emergency response. Among these are fundamental questions such as the incubation time of a virus, its transmission possibilities, and its mortality rate, for instance. Researchers of the Oswaldo Cruz Institute (IOC/Fiocruz) have participated on a study with the goal of clarifying the new coronavirus transmission dynamics and the beginning of the outbreak.

Published in the scientific magazine “Pathogens and Global Health”, the research was carried out by a work group formed by specialists of IOC/Fiocruz, the Biomedical Campus University of Rome, in Italy, and the University of Florida, in the USA. The researchers analyzed 29 Covid-19 complete genetic sequences and two highly similar sequences of SARS-type coronavirus (severe acute respiratory syndrome) originated from bats, available in international databases of the Global Initiative on Sharing All Influenza Data (GISAID) and the National Center for Biotechnology Information (NCBI).

“Identifying the genetic characteristics of the new coronavirus is crucial to elaborate a real-time response to its dispersion, especially based on the genomes that are being published”, emphasized researcher Luiz Carlos Júnior Alcantara, from IOC/Fiocruz. With the use of bioinformatics tools, specialists were able to build phylogeographic analysis that estimate the possible trajectory of the microorganism, and phylogenetic analysis - a family tree of sorts - for the virus.

“The data we found corroborate the current epidemiological picture, indicating the city of Wuhan, in China, as the most likely geographic origin of the outbreak”, explains Marta Giovanetti, a visiting researcher at IOC/Fiocruz. The researchers estimate that the outbreak began in late November 2019. The results also reinforce the hypothesis that the Covid-19 originated from bats, possibly of the Rhinolophus genus.

The study also highlights the importance of tracking down the emergence of new routes or transmission patterns, due to the quick evolution rate and the populational dynamic of the virus.