Outbreak of Washington Covid-19: New variants ignore old “close contact” rules

CNN
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Washington, DC is dealing with a cluster of Covid-19 cases that have been in the spotlight after high-ranking officials were exposed in a series of public events.

Speakers Nancy Pelosi, Senator Susan Collins and Raphael Warnock, and Rep. Peter Defazio announced this week that they were positive.

According to health experts, this outbreak may be rooted in the outdated and confusing guidelines of the Centers for Disease Control and Prevention, at risk of being infected with the virus that causes Covid-19 or infecting others. Useful for evaluation.

On Thursday, Vice President Kamala Harris presided over confirmation of the Senate of Ketanji Brown Jackson without a mask after she announced that she had made close contact with a person who tested positive for Covid-19. However, the CDC guidelines recommend masking around other people at least 10 days after being exposed to the virus.

At a World Health Day press conference that same day, U.S. Department of Health and Human Services Xavier Becerra explained that he and World Health Organization Secretary-General Tedros Adhanom Gebreisesas would wear masks at the event. .. While talking – “Because each of us was near a person who recently tested positive.”

Health experts said Friday that Americans rely on CDC guidance for delayed updates.

From the early days of the pandemic CDC defined Those who have “close contact”, that is, those who are at risk of being infected and spread by the virus. Those who have confirmed Covid-19 in the lab, or who have spent a total of 15 minutes or more within 6 feet of those infected with Covid-19. They said they had Covid-19 by the doctor.

Kimberly Placer, an aerosol scientist at the Scripps Institution of Oceanography, said the rules need to be revisited with newer, more contagious variants such as BA.2, although loose.

“15 minutes and 6 feet didn’t help much in the first place,” she said. “We know that people get infected in shorter times and longer distances.”

Placer believes that the rules of close contact should be based on someone who shares the air in the room for a period of time.

Distances, especially 6 feet, have been included in the equation of infection since the late 1800s, when a scientist named Carl Flügge discovered that respiratory droplets could transmit the infection in the air. increase. He recommended separating people to prevent infection. Scientists tested it using a glass plate and came up with a distance of 6 feet.

In the 1930s, another scientist, William F. Wells, found that some of the droplets coming out of his mouth and nose were large and quickly fell to the ground (within 3-6 feet), but he was sick. One understands that a person can release a small aerosol filled with a virus. It floats in the air for minutes or even hours. They can also be infectious.

Since March 2020, the virus that causes Covid-19 can be transmitted by smaller aerosols, after 52 members of the Skagit County Choir in Washington participated in the practice alone with the disease. The health authorities know. Distance is less important than ventilation and time.

Still, the CDC continues to consider 6 feet in its risk equation.

In response to a question from CNN, a CDC spokesperson said Thursday that authorities have no plans to change the definition of close contacts “at this time.”

“If you were part of an event with multiple infectious diseases, you would have been exposed,” said Dr. Carlos Del Rio, an infectious disease specialist at Emory University.

If you are exposed but have the latest information on vaccination, you should monitor your symptoms and wear a mask for 10 days. This is also a description of CDC.

“If I was in an infected room with Pelosi and others, I was there, so I consider myself intimate,” he said. I don’t know exactly where Pelosi was infected, but she was one of the members who looked like President Biden and Maskless at the signing ceremony on Wednesday. The White House said in a statement that Pelosi was not considered a close contact with the president, according to the CDC’s guidelines.

This is close to how some other countries define exposure.

Until February, when the UK began to withdraw pandemic restrictions, British health authorities had defined broader and closer contact. Their definition included the following:

Linsey Marr, a professor of civil engineering and environmental engineering at Virginia Tech, who studies Aerosol, said the CDC needs to revisit Contact Precautions.

“I think it’s based on an outdated way of thinking about sending, so I think they should update it,” she said.

According to Ma, the CDC probably made a 6-foot-15-minute cutoff to take full advantage of limited public health resources such as contract tracking.

“At this point, it’s more about convenience than science,” she said.

Ma said that all super-popular events have four things in common. Long exposure; poor ventilation; no mask.

“If you are in such a situation, I would say that everyone in the room is potentially exposed,” she said.