Tally of covid

The tally of people infected with the coronavirus after attending a high-profile Centers for Disease Control and Prevention conference in April has risen to at least 181, the agency reported Friday. No one was hospitalized.

The CDC's Epidemic Intelligence Service officers and alumni — the disease detectives deployed to identify and fight outbreaks — met April 24-27 at an Atlanta hotel. The conference drew 1,800 in-person attendees, the first in-person Epidemic Intelligence Service gathering in four years. Like many conferences, it was crowded, with much face-to-face contact, many events held in small rooms and lots of socializing, according to attendees. About 70 percent of participants who responded to a CDC survey said they did not wear masks at the event.

The outbreak of covid-19 cases at the conference underscores the persistence of an evolving and highly infectious virus.

Another CDC global health meeting is scheduled for the same hotel in early June; about 300 to 400 people are expected to attend in person, said one CDC employee who spoke on the condition of anonymity because they were not authorized to speak.

In a "Know Before You Go" document shared with The Washington Post, CDC organizers encourage attendees at the June conference to wear their "own high-quality masks and, if possible, also carry covid-19 rapid tests with them." Organizers of the second conference were informed about the covid outbreak at the earlier event, CDC spokeswoman Kristen Nordlund said. The agency will have masks available if employees want to wear one, she said.

With in-person conferences and summer travel underway, infectious-disease experts say the CDC event is a reminder that the coronavirus is not going away.

"This outbreak dramatically illustrates that if the circumstances are right, this virus can really spread to a lot of people," said William Schaffner, an infectious-disease doctor at the Vanderbilt University School of Medicine. One of his colleagues attended the April CDC conference, and even though the person had a mild illness, like many others at the event, "these were people who were quite discomforted for several days," Schaffner said.

Covid-19 hospitalizations and deaths have fallen dramatically because of immunity conferred by vaccines and prior infections, public health experts have said. Tracking viral circulation or cases has become problematic because many Americans are testing at home, or not all. The end of the public health emergency on May 11 also meant cases and positive test results stopped being reported to the CDC.

The virus can cause significant illness, primarily in unvaccinated people, older adults, people with underlying health conditions and those with weakened immune systems. Among the 181 who were sickened at the CDC conference, the median age was 38, nearly all were younger than 65 and two-thirds were women, Nordlund said. No severe illnesses were reported.

Jeffrey Duchin, health officer for Seattle and surrounding King County, said four members of his team attended the conference. Two wore high-quality masks reliably, he wrote in an email. Of the two who did not, one was sickened by the virus.

"In my view, [Epidemic Intelligence Service] and other conference organizers should take reasonable steps to decrease the risk to participants by optimizing venue indoor air quality … opting for outdoor venues when possible, minimizing crowding, and providing N95 and KN95 masks for those who want to reduce their risk," Duchin said.

"At a minimum, I think it would be useful for conference organizers to inform participants of what steps are being taken to reduce the risk for COVID-19 transmission, so that participants can make informed risk assessments about any additional steps they may want to take, like masking."

At a large travel industry conference that drew nearly 5,000 attendees in San Antonio this week, delegates were told they could choose to wear a face mask. "Please respect the decision of attendees who choose to be masked," said health and safety guidance that was provided.

Greg Staley, senior vice president for communications at the U.S. Travel Association, the conference organizer, said no cases of covid-19 have been reported.

To unravel the cluster of cases tied to the April CDC conference, the agency conducted a May 5-12 survey of in-person attendees, with more than 80 percent responding. Of those who reported testing positive, 52 percent said they had no known prior coronavirus infection. More than 99 percent of respondents had at least one dose of a coronavirus vaccine. About one-fourth of those who tested positive received antiviral medication.

The risk of infection was 70 percent greater among those who attended three or more days compared with those attending two or fewer days, an agency statement said.

The CDC statement said the findings support data that coronavirus vaccines, antiviral treatments and immunity from previous infection continue to provide people with protection against serious illness. It did not reference masking.