Italy was the main source of the first travelers infected by the new coronavirus, the SARS-CoV-2, who arrived in Brazil between February and the beginning of March this year – a period that marks the beginning of the Covid-19 epidemic in the country. The finding was made by Brazilian researchers, in collaboration with colleagues from the United Kingdom, Canada and the United States.
“Unlike China and other countries, where the Covid-19 outbreak started slowly, with a small number of cases initially, in Brazil more than 300 people started the epidemic, mostly from Italy. This resulted in a very rapid spread of the virus, ”says Ester Sabino, director of the Institute of Tropical Medicine (IMT) of the Faculty of Medicine at the University of São Paulo (FM-USP) and one of the authors of the study.
As the main destination of these passengers from the European country was São Paulo, the capital of São Paulo ended up registering the first cases of the disease in Brazil. But, in addition to the city, these travelers also traveled to nine other Brazilian capitals – Rio de Janeiro, Porto Alegre, Salvador, Curitiba, Belo Horizonte, Fortaleza, Recife, Vitória and Florianópolis -, triggering the Covid-19 epidemic in the country.
The results of the study, supported by Fapesp under the Joint Brazil-United Kingdom Center for Discovery, Diagnosis, Genomics and Epidemiology of Arbovirus (CADDE), were described in an article published in the journal “Journal of Travel Medicine”.
Estimates indicated that 54.8% of all cases imported from Covid-19 to Brazil until March 5 were infected travelers in Italy, followed by passengers from China (9.3%) and France (8 , 3%).
The Italy-São Paulo route represented 24.9% of the total number of infected travelers who arrived in Brazil during this period, and the European country was the origin of five of Covid-19’s top 10 import routes to Brazil – China, France, Switzerland, South Korea and Spain -, points out the study.
To identify the most important import routes from Covid-19 to Brazil, the researchers analyzed the history of air travel between February and March 2020 from 29 countries with confirmed cases of the disease, which had as their final destination any Brazilian city.
Based on the total number of passengers who arrived at airports in Brazil in that period from these countries, in addition to the size of the population and the number of cases of the disease registered in these nations between February and March 2020, the proportion of potentially infected travelers was estimated who landed in Brazilian capitals.
The estimates are corroborated by official data from case records of the disease in Brazil, tabulated by the Ministry of Health, which pointed out that 14 of the first 29 patients diagnosed with Covid-19 in Brazil had a history of travel to Italy. Of this total of cases, 6 (23.1%) were registered in São Paulo, the researchers point out.
“It was very clear that São Paulo would be the epicenter of the Covid-19 epidemic in Brazil because it is the city that received the largest number of infected people, mainly from Italy,” says Sabino.
Focus on internal mobility
In the assessment of the researcher, who led the sequencing of the coronavirus genome isolated from the first two confirmed cases of Covid-19 in Brazil, in order to contain the spread of the disease in Brazil, the focus now should be on restricting internal mobility in country, since transmission became sustained or community-based.
An important action in this regard would be to restrict the movement of residents of São Paulo, where the largest number of cases of infection with the new coronavirus is concentrated, says Sabino.
“São Paulo and Rio de Janeiro, to a lesser extent, will be the centers of distribution of the coronavirus to Brazil. Therefore, it is necessary to restrict the departure of people from these locations ”, he says.
The group of researchers coordinated by Sabino continues to sequence coronaviruses isolated from Brazilian patients diagnosed with the disease.
However, the work had to be stopped due to the suspicion that researchers from the group itself could also have been infected with the new coronavirus.
“We had to stop the laboratory and we are returning now. We will analyze if we can sequence a larger number of virus genomes ”, says Sabino.
The speed of transmission of the new coronavirus in the country also ended up running over the researchers’ schedule and plans.
“The transmission of the virus is going so fast that the sequencing data cannot help to understand how the epidemic is progressing as we planned”, ponders Sabino.
The researchers’ expectation was that as sporadic cases of the disease appeared, they would be sequenced to follow the transmission path, in order to generate control strategies. They ended up, however, with many cases for sequencing that arrived at the laboratory at the same time.
“It will not be possible to control the outbreak with sequences alone. The epidemic is progressing very fast and it is no longer possible to follow the cases ”, says Sabino.
To date, nearly 800 sequences of coronavirus genomes isolated from infected patients worldwide have been carried out.
This set of sequencing, made available in public databases, will allow studies of primary resistance of promising antivirals to combat the new coronavirus, says Sabino.
“When a candidate drug appears, surely this database for sequencing the virus genome will be useful for this purpose”, he says.