The WHO was against travel restrictions as they detailed in a press release at the end of February. But in the month past (March) practically every country on earth has instituted travel restrictions, most recently China, which is now afraid of being reinfected from abroad.
So, has the WHO changed their public stance in any way about travel restrictions by now? I searched a bit, but it seems they've gone mum on the topic of travel, while (of course) strongly advocating for social distancing in general. (Aside: the WHO wants us to use "physical distancing" as the more appropriate term for that.)
I haven't done anything like a survey on this, but clearly some governments include "minimize travel" in the physical distantincing advice they give, e.g. Australia's
Government advice for implementing physical distancing has mainly urged people to isolate themselves in space: staying at least 1.5 metres apart, working from home, avoiding gatherings, and minimising travel.
So maybe the WHO has done the same somewhere in their recommendations and I've missed it.
Likewise, there have been at least three (high-profile) publications in Science this month on this:
the travel quarantine of Wuhan delayed the overall epidemic progression by only 3 to 5 days in Mainland China, but has a more marked effect at the international scale, where case importations were reduced by nearly 80% until mid February. Modeling results also indicate that sustained 90% travel restrictions to and from Mainland China only modestly affect the epidemic trajectory unless combined with a 50% or higher reduction of transmission in the community.
It remains unclear how these unprecedented interventions, including travel restrictions, affected COVID-19 spread in China. We use real-time mobility data from Wuhan and detailed case data including travel history to elucidate the role of case importation on transmission in cities across China and ascertain the impact of control measures. Early on, the spatial distribution of COVID-19 cases in China was explained well by human mobility data. Following the implementation of control measures, this correlation dropped and growth rates became negative in most locations, although shifts in the demographics of reported cases were still indicative of local chains of transmission outside Wuhan. This study shows that the drastic control measures implemented in China substantially mitigated the spread of COVID-19.
The Wuhan shutdown was associated with the delayed arrival of COVID-19 in other cities by 2.91 days (95%CI: 2.54-3.29). [...] This analysis provided no evidence that the prohibition of travel between cities, which was implemented after and in addition to the Wuhan shutdown on 23 January, reduced the number of cases in other cities across China. These results are robust to the choice of statistical regression model. [It also analyzes, and finds effective (via association), most city-level social-distancing measures:] Our model suggests that, without the Wuhan travel ban or the national emergency response, there would have been 744,000 (± 156,000) confirmed COVID-19 cases outside Wuhan by 19 February, day 50 of the epidemic. With the Wuhan travel ban alone, this number would have decreased to 202,000 (± 10,000) cases. With the national emergency response alone (without the Wuhan travel ban), the number of cases would have decreased to 199,000 (± 8500). Thus, neither of these interventions would, on their own, have reversed the rise in incidence by 19 February. But together and interactively, these control measures offer an explanation of why the rise in incidence was halted and reversed, limiting the number of confirmed cases reported to 29,839 (fitted model estimate 28,000 ± 1400 cases), 96% fewer than expected in the absence of interventions.
So maybe there's a "wind of change" in the scientific community on this, maybe not, but perhaps it's too early to tell what the consensus might become on this. So I'm "holding off" on accepting the answer below for now (based on a non-mention in a March 11 WHO statement) as rather inconclusive.