COVID-19 spreads even before people show symptoms, study says

Sao Paulo, June 20: Brazil’s government confirmed on Friday that the country has risen above 1 million confirmed coronavirus cases, second only to the United States.

The country’s health ministry said that the total now stood at 10,32,913, up more than 50,000 from Thursday. The ministry said the sharp increase was due to corrections of previous days’ underreported numbers.

Brazilian President Jair Bolsonaro still downplays the risks of the virus after nearly 50,000 deaths from COVID-19 in three months, saying the impact of social isolation measures on the economy could be worse than the disease itself.

Specialists believe the actual number of cases in Brazil could be up to seven times higher than the official statistic. Johns Hopkins University says Brazil is performing an average of 14 tests per 1,00,000 people each day, and health experts say that number is up to 20 times less than needed to track the virus.

Official data show a downward trend of the virus in Brazil’s north, including the hard-hit region of the Amazon, a plateau in cases and deaths in the countries’ biggest cities near the Atlantic coast, but a rising curve in the south.

In the Brazilian countryside, which is much less prepared to handle a crisis, the pandemic is clearly growing. Many smaller cities have weaker health care systems and basic sanitation that’s insufficient to prevent contagion.

“There is a lot of regional inequality in our public health system and a shortage of professionals in the interior,” said Miguel Lago, executive director of Brazil’s Institute for Health Policy Studies, which advises public health officials.

That creates many health care deserts, with people going long distances to get attention. When they leave the hospital, the virus can go with them.

The cattle-producing state of Mato Grosso was barely touched by the virus when it hit the nation’s biggest cities in March. Sitting far from the coast, between the Bolivian border and Brazil’s capital of Brasilia, its 33 lakh residents led a mostly normal life until May. But now its people live under lockdown and meat producers have dozens of infected workers.

In Tangará da Serra, a city of 1,03,000 people in Mato Grosso, the mayor decided Friday to forbid the sale of alcoholic drinks for two weeks as an incentive for people to stay home.

Fᢩo Junqueira said the measure was needed after a spike in COVID-19 cases that filled 80% of the city’s 54 intensive care beds. The city has had nearly 300 cases of the disease, plus three fatalities.

In Rondonópolis, only 300 miles away from Tangará da Serra and home to a thriving economy, health authorities closed the local meatpacking industry after 92 cases were confirmed there. The city of 1,44,000 inhabitants counted 21 deaths from the virus and more than 600 cases. The mayor has also decided to limit sales of alcoholic beverages.

Even regions once considered examples of successful efforts against the virus are now struggling.

Porto Alegre, home to about 14 lakh people, had success in slowing the virus’ spread over the last three months. But now its mayor is considering increasing social isolation measures after ICU occupancy in the city jumped to 80% this month.

We were already making projections for schools to come back, Mayor Nelson Marchezan Jr. told The Associated Press. Now the trend is to impose more restrictions. Outside Sao Paulo city, five regions of the state’s countryside will have to close shops starting Monday due to a rise in coronavirus cases. Governor João Doria announced the decision Friday.

Dr. Mike Ryan, the World Health Organization’s executive director, said at a news conference that Brazil needs to increase its efforts to stop the spread of infections.

“The epidemic is still quite severe in Brazil. I believe health workers are working extremely hard and under pressure to be able to deal with the number of cases that they see on a daily basis,” Dr. Ryan said.

“Certainly the rise is not as exponential as it was previously, so there are some signs that the situation is stabilising. But we’ve seen this before in other epidemics in other countries.”

Margareth Dalcolmo, a clinical researcher and professor of respiratory medicine at the state-funded Oswaldo Cruz Foundation in Rio de Janeiro, believes the reopening in major cities and the virus traveling by road into Brazil’s heartland will keep the pressure on the country’s health system.

“The risk in the interior now is very big,” she said. “Our health system just can’t solve the most serious cases of COVID in many places of the countryside.”

London, May 20: The current physical distancing guidelines of 6 feet may be insufficient to prevent COVID-19 transmission, according to a study which says a mild cough in low wind speeds can propel saliva droplets by as much as 18 feet.

Researchers, including those from the University of Nicosia in Cyprus, said a good baseline for studying the airborne transmission of viruses, like the one behind the COVID-19 pandemic, is a deeper understanding of how particles travel through the air when people cough.

In the study, published in the journal Physics of Fluids, they said even with a slight breeze of about four kilometres per hour (kph), saliva travels 18 feet in 5 seconds.

"The droplet cloud will affect both adults and children of different heights," said study co-author Dimitris Drikakis from the University of Nicosia.

According to the scientists, shorter adults and children could be at higher risk if they are located within the trajectory of the saliva droplets.

They said saliva is a complex fluid, which travels suspended in a bulk of surrounding air released by a cough, adding that many factors affect how saliva droplets travel in the air.

These factors, the study noted, include the size and number of droplets, how they interact with one another and the surrounding air as they disperse and evaporate, how heat and mass are transferred, and the humidity and temperature of the surrounding air.

In the study, the scientists created a computer simulation to examine the state of every saliva droplet moving through the air in front of a coughing person.

The model considered the effects of humidity, dispersion force, interactions of molecules of saliva and air, and how the droplets change from liquid to vapour and evaporate, along with a grid representing the space in front of a coughing person.

Each grid, the scientists said, holds information about variables like pressure, fluid velocity, temperature, droplet mass, and droplet position.

The study analysed the fates of nearly 1,008 simulated saliva droplets, and solved as many as 3.7 million equations.

"The purpose of the mathematical modelling and simulation is to take into account all the real coupling or interaction mechanisms that may take place between the main bulk fluid flow and the saliva droplets, and between the saliva droplets themselves," explained Talib Dbouk, another co-author of the study.

However, the researchers added that further studies are needed to determine the effect of ground surface temperature on the behaviour of saliva in air.

They also believe that indoor environments, especially ones with air conditioning, may significantly affect the particle movement through air.

This work is important since it concerns safety distance guidelines, and advances the understanding of the transmission of airborne diseases, Drikakis said.

Jun 9: The World Health Organization says it still believes the spread of the coronavirus from people without symptoms is “rare,” despite warnings from numerous experts worldwide that such transmission is more frequent and likely explains why the pandemic has been so hard to contain.

Maria Van Kerkhove, WHO''s technical lead on COVID-19 said at a press briefing on Monday that many countries are reporting cases of spread from people who are asymptomatic, or those with no clinical symptoms.

But when questioned in more detail about these cases, Van Kerkhove said many of them turn out to have mild disease, or unusual symptoms.

Although health officials in countries including Britain, the U.S. and elsewhere have warned that COVID-19 is spreading from people without symptoms, WHO has maintained that this type of spread is not a driver of the pandemic and is probably accounts for about 6 per cent of spread, at most.

Numerous studies have suggested that the virus is spreading from people without symptoms, but many of those are either anecdotal reports or based on modeling.

Van Kerkhove said that based on data from countries, when people with no symptoms of COVID-19 are tracked over a long period to see if they spread the disease, there are very few cases of spread.

“We are constantly looking at this data and we''re trying to get more information from countries to truly answer this question,” she said. “It still appears to be rare that asymptomatic individuals actually transmit onward.”