In early February, 57 people arrived at a Nebraska military base, among the first Americans evacuated from Wuhan, China, the epicenter of the new coronavirus outbreak. US health officials knew very little then about the mysterious new virus, and the quarantined group offered an early opportunity to size up the threat.

The federal government sought help from a team at the University of Nebraska Medical Center, including Dr. James Lawler, an experienced infectious disease specialist. Lawler told Reuters he immediately asked the world-renowned US Centers for Disease Control and Prevention (CDC) for permission to test the quarantined group, deeming it crucial to know whether people without symptoms were infected and could spread the deadly pathogen.

Agency officials worried that detained people couldn't give proper consent because they might feel coerced into testing. "CDC does not approve this study," an official at the quarantine site wrote to Lawler in a Feb. 8 email obtained by Reuters. "Please discontinue all contact with the travelers for research purposes."

More than two months passed before the CDC expanded its testing guidelines to include all asymptomatic people, saying soon afterward that this silent spread "may meaningfully contribute to the propagation of the COVID-19 pandemic." By November, the agency estimated that more than half of cases were spread by people not currently experiencing symptoms.

Critics have widely asserted that the CDC fumbled key decisions during the coronavirus scourge because then-President Donald Trump and his administration meddled in the agency's operations and muzzled internal experts. The matter is now the subject of a congressional inquiry. Yet Reuters has found new evidence that the CDC's response to the pandemic also was marred by actions - or inaction - by the agency's career scientists and frontline staff.

At a crucial moment in the pandemic when Americans were quarantined after possible exposure to the virus abroad, the agency declined or resisted potentially valuable opportunities to study whether the disease could be spread by those without symptoms, according to previously undisclosed internal emails, other documents and interviews with key players.

Soon after balking at testing the returnees from Wuhan, the agency delayed testing asymptomatic passengers among 318 evacuees from the Diamond Princess, a contaminated cruise ship in Japan. In addition, the agency failed at that time to make effective use of outside experts and appeared at times unprepared for the crisis on the ground, lacking adequate personal protective gear and ignoring established protocols, Reuters found.

"Yes, they were interfered with politically," said Lawrence Gostin, director of the O'Neill Institute for National and Global Health Law at Georgetown University, referring to alleged meddling by the Trump administration. "But that's not the only reason CDC didn't perform optimally during COVID-19. There are a lot of things that went wrong."

Four top public health experts or ethicists told Reuters that the question of whether to test or engage in research on detained people has always been a sensitive topic. But all said the CDC should have proceeded given the fast-moving public health emergency.

Moreover, the CDC finalized rules in 2017 providing that medical testing was expressly allowed in quarantine, as long as participants were given the opportunity to give "informed consent" or opt out. Informed consent means giving people adequate information to understand the risks and benefits of a test or procedure.

Gostin said the CDC's argument against testing was "unreasonable" under the circumstances. "You are asking for consent and not imposing any harm," he said. "There is a good reason to do it."

It's difficult to know whether more aggressive early testing among asymptomatic people would have significantly altered the trajectory of the pandemic in the United States, which has infected 24 million people and killed more than 400,000.

The CDC was not the only agency that struggled with this issue. Notably, an official with the World Health Organization called asymptomatic spread "very rare" in June, only to say a day later "we don't actually have that answer yet." In recent months, the WHO has said infected people without symptoms can be contagious, but "it is still not clear how frequently this occurs."

Still, some countries such as South Korea and Singapore used widespread testing early on to identify infected people with or without symptoms and, unlike the United States, broadly required or distributed masks.

CDC scientists infamously botched the creation of a test for the coronavirus and took weeks trying to fix it, making widespread testing - well beyond those with symptoms - impossible during the pandemic's first months.

In response to detailed inquiries from Reuters, a CDC spokesman said the agency declined to comment.

In the final weeks of the Trump administration, White House officials did not respond to requests for comment on reports of political interference.

The problems within the CDC, which has suffered from a decade of declining funding, point to the steep challenge faced by newly inaugurated President Joe Biden and his CDC director, Rochelle Walensky, to rehabilitate the agency in the eyes of scientists, other public health officials and the public.

Walensky "acknowledges that work has to be done to restore public confidence" in the CDC, according to a Biden spokesperson.

Dr. Sonja Rasmussen, who worked at the CDC for 20 years and at one point was responsible for pandemic influenza preparedness, said the agency's staff are "among the most dedicated professionals in the world and they were doing the best they could under the toughest circumstances."

"This has been an incredibly challenging pandemic and it would have been hard for anyone to guess what would have happened," she said.

But she and other public health specialists also told Reuters that Americans deserve a thorough examination of the agency's shortcomings in the crisis.

"We have to figure out what needs to be fixed before this happens again," said Rasmussen, now a professor at the University of Florida.

REQUEST DENIED

On Feb. 7, a group of Americans arrived from Wuhan and the surrounding province at Camp Ashland, a National Guard base near Omaha and the University of Nebraska Medical Center, a major outpost in the nation's defenses against bioterrorism and infectious diseases.

Infectious disease specialist Lawler, who worked in the George W. Bush and Obama administrations on pandemic response, suspected that some of the evacuees might be infected with the coronavirus and shedding it despite having no symptoms. His suspicions were based partly on scientific reports from Asia and Europe.

Starting on Feb. 8, Lawler pressed the CDC to greenlight voluntary and limited coronavirus testing among this group, according to emails obtained by Reuters through the Freedom of Information Act.

Lawler had already won support for such testing from the US Health and Human Services (HHS) officials in charge of the returnees at Ashland, the Nebraska health department and his university's medical faculty, emails show. HHS oversees the CDC.

Later that Saturday, Eric Kasowski, the CDC's representative at Camp Ashland, emailed Lawler to tell him that his request to test the 57 people in quarantine "was very quickly elevated to Dr. (Anne) Schuchat, Principal Deputy Director, CDC," who had worked at the agency for 32 years.

Schuchat referred questions from Reuters to the CDC press office, which declined to comment.

The CDC's answer to Lawler was no.

According to the Feb. 8 email: "It is CDC's position that since the research is being proposed for a group of individuals who are detained under a federal quarantine order, the circumstances of voluntary participation would be extremely difficult to assure and therefore, CDC does not approve this study."

Lawler said he kept pressing Kasowski. But Kasowski told Lawler the next morning that the testing proposal had been rejected again, this time by officials up to and including CDC director Robert Redfield.

"This is absurd," Lawler recalled telling Kasowski.

Kasowski declined to comment, referring questions to the CDC.

Instead of having everyone tested during the two-week quarantine, only one returnee who became ill and was hospitalized got tested; the results were negative for coronavirus, Lawler said. The other 56 left quarantine without knowing whether they carried the virus, and Lawler said he knows of no CDC follow up with that group.

In a Feb. 10 email to Kasowski, Lawler warned that the federal government, by not testing symptomless individuals, "may be missing the submerged iceberg in the US"

MAJOR PROBLEMS

Within days, Lawler got a new federal assignment: to help evacuate more than 300 Americans stranded on the Diamond Princess cruise ship docked in Yokohama, Japan.

He was joined there by Dr. Michael Callahan, a veteran infectious disease specialist from Massachusetts General Hospital, who had just been appointed a special advisor to HHS on COVID-19. Callahan, who says his two years of physician scientist training at the CDC in the mid-1990s inspired him to forgo academia for a field career battling disease outbreaks, had just treated coronavirus patients in China weeks earlier.

Major problems emerged soon after Lawler and Callahan arrived in Yokohama on Feb. 14.

The US team, including HHS and other US personnel, had to borrow walkie talkies from Japanese authorities because they didn't have mobile phones that worked internationally, according to an "after-action" report submitted by Lawler and Callahan in March to HHS and obtained by Reuters.

Japan had to lend the US team basic protective gear because the Americans' supplies didn't arrive in time, the report said. Some team members were not trained for handling a "highly contagious disease."

According to Callahan, he had to turn back two CDC staffers seeking to board the Diamond Princess in Japan because they had no current experience in emergency medicine and infection control.

Callahan said the problem was not isolated to the CDC's coronavirus response. In his regular interactions in the field with CDC staff in recent years, he said, he has seen "a progressive degradation of clinical expertise and incident management," particularly during Ebola outbreaks in Africa.

The CDC needs "people that can actually do public health when bad stuff happens," Callahan said.

NOT ENOUGH PROOF

On Feb. 17, Lawler flew with 151 cruise passengers to Lackland Air Force Base near San Antonio, Texas. An isolation bubble was created using a plastic curtain in the rear of the plane for five passengers who had tested positive for COVID-19 in Japan.

During the flight, Lawler moved two passengers who had become feverish to the isolation area, planning to take them to Nebraska Medical Center. But those precautions went awry when CDC personnel greeted the plane in Texas.

"The CDC officer in charge boarded the aircraft without consulting the flight crew regarding safety or contamination issues," according to the after-action report.

The officer's personal protective equipment "was grossly insufficient due to the high level of contamination that likely existed on the aircraft. This likely put CDC personnel and other responders on the ground at risk."

What's more, the CDC official moved the two people who had developed symptoms mid-flight back with the group of healthy passengers, and the CDC's handling of the flight violated disaster medicine protocols, according to the report. The CDC official is not named in the report.

Similar problems occurred when Callahan arrived with another group of 167 Diamond Princess passengers at Travis Air Force Base in Northern California and a CDC officer boarded the plane, the report said.

Meantime, officials at Nebraska's public health laboratory, who had been working with Lawler, asked the CDC for permission to test passengers from the Diamond Princess while they were under quarantine, even if they didn't have symptoms, emails show.

A CDC influenza expert, Dr. Tim Uyeki, wrote back on Feb. 17 to the director of the Nebraska Public Health Laboratory that the agency only wanted to test symptomatic individuals and those who had previously tested positive in Japan, citing a lack of detail on the accuracy of the Japanese tests.

Uyeki declined to comment and referred questions to the CDC press office.

Lawler and Callahan said they flew in late February to CDC headquarters in Atlanta to meet with Redfield and other senior officials, to raise concerns about the flawed evacuation and potential for asymptomatic spread based on their observations from the Diamond Princess.

Lawler said CDC officials replied that there wasn't enough proof yet that people without symptoms spread the disease.

Redfield did not return requests for comment.

Meanwhile, at both quarantine sites in Texas and California, CDC staff began to test some cruise passengers without symptoms who previously had tested positive in Japan, according to Dr. Bela Matyas, the local health officer in California's Solano County, as well as emails between the Nebraska hospital personnel and the CDC.

The CDC officials had doubts about the accuracy of testing done by Japanese authorities, but the results confirmed that at least some of the passengers were indeed positive - 16 at the California base alone, Matyas said. Texas numbers were not available.

During the second week of quarantine in late February, the CDC and local health officials began offering tests to all of the cruise passengers. In California, where most sought testing, 10 more people were found to have COVID-19, Matyas said.

Despite this evidence of infections without symptoms, the CDC made no immediate changes in its public guidance on asymptomatic infection.

'FAIRLY COMMON'

By March, signs of asymptomatic spread were mounting in the United States and abroad.

A tipping point for the CDC came when staffers were deployed to the outskirts of Seattle to handle an outbreak at the Issaquah Nursing and Rehabilitation Center, a relatively confined setting. King County and CDC officials tested 76 of the 82 residents, regardless of whether they exhibited symptoms, beginning on March 13, according to the CDC.

They found 23 infected, 13 asymptomatic at the time. Ten of those went on to develop symptoms.

"That was really ... our first hint that asymptomatic transmission was fairly common, especially in those settings," said Dr. James Lewis, an official with the county health department's COVID-19 response, in an interview.

Two weeks later, on March 27, the CDC published the case study as evidence of asymptomatic infection. That same week, for the first time, the agency recommended testing health workers and first responders, even without symptoms.

In a radio interview that aired on March 31, Redfield said, "We have learned that in fact" symptomless individuals "do contribute to transmission."

Based on that evidence, the CDC recommended that even asymptomatic people wear cloth face coverings in public areas. Almost a month later, on April 27, the agency expanded its testing guidelines to include "persons without symptoms."

That was 11 weeks after Lawler's first request to test the Wuhan group in Nebraska.