The WHO was largely opposed to travel restrictions to deal with COVID19.
Many countries went ahead and imposed travel restrictions regardless. Did those countries base their travel restrictions upon expert advice that doing so would reduce the harm caused by the pandemic? I’m primarily interested in restrictions to international travel, but restrictions on inter-state or on travel in different regions within a state (like in Western Australia) are also ok.
In the US, the answer would be yes in the sense that government (CDC) experts seem to have supported external but not internal travel restrictions. (Some CDC officials seem to have argued that travel restrictions on Europe should have come sooner.) The only thing you can find out for sure is that the CDC "contributed" to those decisions as part of the coronavirus task force. What they said exactly in those meetings is not [yet] public.
The press gets to ask them about these almost always post-hoc, after a government decision is announced, so unless more documents are released, we probably won't know for sure what the decision process was. But some of the carefully worded statements of CDC officials seem to point to what I summarized in my first/para sentence. E.g. Fauci almost certainly recommended the external travel bans, but seems to have opposed or not supported the internal/domestic ones (in the US at least). And Schuchat said those things about Europe travel restrictions not having been implemented soon enough, more recently.
In more detail On Feb 26 Fauci was paraphrased as saying
Stringent travel restrictions imposed on inbound flights from China to contain the coronavirus outbreak become “irrelevant” in a potential pandemic because “you can’t keep out the entire world,” a top U.S. health official said a day after the Trump administration braced the public for its eventual spread here.
“When it was focused only on China, we had a period of time, temporary, that we could do a travel restriction that prevented cases from coming into the U.S.,” Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told CNBC’s “Squawk on the Street.” “When you have multiple countries involved, it’s very difficult to do; in fact, it’s almost impossible.”
He added that the Chinese have been very efficient in containing the disease, however, they have used “draconian” methods in doing so, such as shutting down entire cities. Fauci said he doubts the U.S. would adopt similar methods.
I think Fauci also supported the ban on travel from Europe, mid-March, but I can't find an immediate quote on that, except after Trump adopted those measures:
Dr. Anthony Fauci, the widely-respected director the National Institute of Allergy and Infectious Diseases, and Centers for Disease Control and Prevention Director Dr. Robert Redfield, appeared before the House Oversight Committee for a second day of questioning Thursday and backed President Trump's travel ban from much of Europe.
"The real risk in general right now and this is why the president took the action he did last night within the world now over 70 percent of the new cases are linked to Europe" Redfield said. "Europe is the new China, and that's why the president made those statements."
Note that in hindsight some other CDC officials have said (more recently, in May) that the US imposed a travel restrictions on Europe far too late:
Limited testing and delayed travel alerts for areas outside China contributed to the jump in U.S. cases starting in late February, said Dr. Anne Schuchat, the No. 2 official at the U.S. Centers for Disease Control and Prevention.
“We clearly didn’t recognize the full importations that were happening,” Schuchat told The Associated Press. [...]
The CDC on Friday published an article, authored by Schuchat, that looked back on the U.S. response, recapping some of the major decisions and events of the last few months.
It suggests the nation’s top public health agency missed opportunities to slow the spread. [...] in her article, Schuchat noted that nearly 2 million travelers arrived in the U.S. from Italy and other European countries during February. The U.S. government didn’t block travel from there until March 11.
“The extensive travel from Europe, once Europe was having outbreaks, really accelerated our importations and the rapid spread,” she told the AP.
”I think the timing of our travel alerts should have been earlier.”
It's not terribly clear from that what and when the CDC recommended to the WH in re Europe though.
Even with respect to the restrictions imposed much more quickly by the US on China (in about a week after China announced its extensive internal restrictions), Reuters described some disputes within the administration based on unnamed sources, although in public statements, the administration rejected this version of events. I'll spare you the he-said-he-said parts, but what we know more certainly:
The NSC staff ultimately proposed aggressive travel restrictions to high-level administration officials - but it took at least a week more for the president to adopt them, one of the government officials said.
[...] Each day that the administration debated the travel measures, roughly 14,000 travelers arrived in the United States from China, according to figures cited by the Trump administration. [...]
It is unclear when the president was made aware of the NSC’s proposal and what prompted his decision to act, but the decision followed the World Health Organization’s declaration the day before that the epidemic was a “public health emergency of international concern.”
U.S. Centers for Disease Control and Prevention officials told Reuters that they contributed to the decision as part of the administration’s newly convened coronavirus task force.
Note also however that contra to the Chinese approach of banning internal/domestic travel from the most infected areas within China, Fauci didn't push (or might have had strong reservations, even in mid March) about imposing any internal/domestic travel restrictions in the US. Regarding the latter, he was quoted as saying:
Fauci, a member of the administration’s coronavirus task force, said on ABC’s “This Week” that the group has discussed “every possibility,” but domestic travel restrictions “have not been seriously discussed.”
“I mean, they've been discussed, but not seriously discussed,” he said. “I don't see that right now or in the immediate future. But remember, we are very open-minded about whatever it takes to preserve the health of the American public.”
The effects of the [internal and external] travel restrictions are still the topic of intense academic/expert scrutiny, e.g. I'll link just the latest paper in Science (Apr 24) on that, that I know of.
