COVID-19 and heat: Temperatures, coronavirus cases climb in tandem across the US

Temperatures continue to sizzle across most of the United States this week as many states combat climbing coronavirus cases.

Some experts were hopeful that the summer heat would dissipate the COVID-19 virus and provide a brief period of relief, but others expressed reservations on the notion of heat having a dampening effect on the virus in the early days of the pandemic, since many areas where the virus had begun to spread were in the midst of hot summers already.

“I never thought that,” Dr. William Hanage, an associate professor of epidemiology at Harvard University, said. “I think that what we have been seeing across the South and indeed in Brazil has suggested that temperature really doesn’t get too much in the way of this virus, unfortunately.”

Hanage said that a lot of the confusion surrounding the virus has come from the public comparing the coronavirus to the flu.

“It’s not really like the flu. It’s a respiratory virus, but beyond that it’s not that much in common. The flu does show a strong seasonality, and part of the reason for that is that it transmits in cold, dry environments. When it gets hot and humid, like now, it’s not good for flu,” Hanage said.

Hanage said COVID-19 is not significantly affected by the change in the seasons, and thus transmission has been happening during the summer pretty effectively. “People like me have known that transmission was not going to go away in the heat for some time, months, since the winter. We just didn’t know how big the impact would be.”

According to Hanage, the risk of transmission is higher indoors. And with the country’s scorching summer temperatures, this can cause additional issues as people try to congregate inside to beat the heat.

Hanage’s expectation is that we will continue to see transmission over the summer months unless something is done to stop it.

“This is not over,” Hanage said. “It’s going to be with us for a really long period of time, and so managing to remember that this is a marathon, not a sprint, and being able to take steps now, which are going to be sustainable, which are going to protect you and your family.”

Hanage said those steps include wearing a mask, since this will make it more difficult for the virus to transmit. “A virus getting into another host is everything,” Hanage said.

A sweltering heat wave continues in the U.S.

Temperatures soared over the weekend as several cities in the United States reported daily record-high temperatures.

Palm Springs, California reached a record high of 121 degrees on Sunday. Phoenix and Tucson Arizona, along with Borger, Texas also reached daily record-high temperatures.

Other cities also experienced triple-digit heat. Amarillo, Texas and Roswell, New Mexico tied records for the daily high temperature on Sunday.Death Valley, California, the country’s hottest location, reached a sweltering 128 degrees Sunday.

While this temperature did not break a record, it was the area’s hottest temperature of the year so far.

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Parts of the Midwest also experienced sweltering conditions. Last week, Buffalo, New York and Muskegon Michigan experienced record-long streaks of 90-plus-degree days.

Record heat will continue to sear parts of Texas and the Desert Southwest over the next few days. The area of high pressure responsible for the hot conditions will expand east over the next few days, likely bringing above average temperatures to most of the country.

Despite soaring mercury, COVID-19 cases continue to spike

As of July 13, the number of new COVID-19 cases continues to trend upward in 38 states across the United States, according to tracking analysis at John Hopkins University.

The number of new coronavirus cases in Florida reported Sunday marked the highest single-day total of any state since the start of the pandemic. The state reported over 15,000 new COVID-19 cases, according to the Florida Department of Health.

Arizona, a state that just smashed heat records in two major cities, has seen major increases in cases over the past couple weeks. Over the past seven days, nearly 27% of tests came back positive, which is currently the highest positivity rate for COVID-19 tests in the country.

In Texas, the positive test rate rose from 15.81% to 16.33% on Sunday, a record high for the state, according to a Houston Chronicle analysis. As of Sunday, there had been an 89 percent growth in the number of patients hospitalized statewide from two weeks ago.

Recent studies on heat’s effect on COVID-19 are not consistent

According to scientists, there is not enough evidence to know if the rise in temperatures affects transmission rates, as recent studies related to COVID-19 and the heat continue to be conflicting and inconsistent.

One study in Mainland China showed that a 1°C increase in the average temperature led to a decrease in the daily confirmed cases by 36% to 57%.

Another study, published in the Social Science Research Network out of China found a reduction in COVID-19 reproduction rates due to high temperature and humidity levels.

But in countries such as Iran and Australia, COVID-19 spread very quickly, despite the warm and humid conditions.

According to a paper published in April by the National Academy of Sciences, Engineering, and Medicine, the virus is unlikely to be seasonal in nature. The study said that the number of well-controlled studies showing reduced survival of the coronavirus in elevated temperatures and humidity was small.

“Given that countries currently in ‘summer’ climates, such as Australia and Iran, are experiencing rapid virus spread, a decrease in cases with increases in humidity and temperature elsewhere should not be assumed," a media advisory on the study read.