It's always in the best interest of the country to close its own borders, regardless of what WHO or any other country says. If WHO advised against travel ban, then they were wrong. US was right to close the border early on with China, but they delayed in closing borders with Italy (and later on the UK), even though there were huge infection clusters in those countries at that time. Likewise for most of Europe, since looking at the phylogenetic tree of the coronavirus, the majority of viral haplotypes belong to the same viral strain found in Italy rather the strain from China, meaning they were most likely directly spread from Italy rather than China. Therefore, neighbouring countries around China who closed borders early had very little infections (Afghanistan, Kazakhstan, Mongolia, Laos, Taiwan, Singapore). But neighbouring countries around Italy did not close borders with Italy until it was too late (many not until mid March), therefore the virus easily spread to pretty much every country in Europe.
By that time everyone was already taking massive precautions via gloves, hand washing and use of hand sanitizers/alcohol sprays, so transmission via surface contact would be minimal.