Air travel helped spread novel coronavirus in Brazil

Domestic and international air travel helped spread the novel coronavirus in Brazil, a study has found, as tourism bodies push for global travel to resume amid infection resurgences in some countries.

The collapse of global tourism during the COVID-19 pandemic has cost the industry US$320 billion, according to the UN World Tourism Organization (UNWTO).

The drive to restart the industry has already begun: UNWTO analysis shows that 40 per cent of global destinations have eased restrictions to encourage tourists to return.

Brazil, which now has the second-highest number of confirmed cases in the world, reopened to international travel on Wednesday. In Vietnam earlier this week, 80,000 domestic tourists were flown out of the coastal resort city of Da Nang after a local COVID-19 outbreak.

Tourism last year supported almost 40 million jobs in India, according to the World Travel and Tourism Council. The economic impact of global travel restrictions is too damaging to ignore, UNWTO secretary-general Zurab Pololikashvili says.

The dramatic fall in international tourism places many millions of livelihoods at risk, including in developing countries. Governments in every world region have a dual responsibility: to prioritise public health while also protecting jobs and businesses."

Zurab Pololikashvili, UNWTO Secretary-General

Brazil virus spread

However, a study from Brazil emphasises the role of long-distance flights into the country and between Brazilian cities in spreading SARS-CoV-2, the virus that causes COVID-19. Brazil has one of the worst COVID-19 death tolls in the world.

The research into the effects of travel in Brazil, published in Science (23 July), shows that although the country stopped 90 per cent of air travel from March, the virus spread from large urban centres to other regions of the country.

While the restrictions reduced the contagion rate — known as R in epidemiology — by half, it was not enough to drop the R to the ideal number of less than one, according to experts.

"Until mobility was reduced, on March 16, Brazil was going through a period of celebration [Carnival] and social meetings that probably spread the first cases," explains Ester Sabino, from the Institute of Tropical Medicine of the University of São Paulo and one of the coordinators of the research funded by the State of São Paulo Research Foundation (FAPESP).

Lead author Darlan S. Cândido, from the University of Oxford's Department of Zoology, tells SciDev.Net that continued long-distance travel within Brazil spread the virus. "Despite the massive reduction in the number of domestic flights, those with the longest distance were less affected and lost fewer passengers, which means that people travelled less but further," he says.

The study shows that between late February and early March there were at least 102 international introductions of the virus into Brazil, from 18 virus strains, but only three of them — from Europe — created a chain of transmission.

In Brazil, there have been more than 2.5 million reported cases of COVID-19 and more than 91,000 deaths.

Travel links

The study traced the trajectory of the epidemic based on the sequencing of 427 viral isolates from Brazilian patients, collected in 85 cities in 18 states.

Two types of the virus prevalent in the southern states of São Paulo and Rio de Janeiro were later found in the northern Amazon region, which, in June, became the epicentre of the epidemic in Brazil. The fatality rate in the north doubled that of the country as a whole, reaching 43 per 100,000 people.

"These findings emphasise the role of social mobility between states as a key factor in the interregional spread of the virus, with highly populated and well-connected urban concentrations in the southeast region that act as the main sources of virus export in the country," the study authors say.

Epidemiologist Paulo Nadanovsky, from Brazil's National School of Public Health, says: "Geography and population size are still believed to be central factors in explaining the evolution of the epidemic, when in fact the central problem is mobility."

"The current level of effort to contain the spread of the virus is insufficient. If mobility is not limited, the places that did not have outbreaks will have it," says Nadanovsky, who was not involved in the study.

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