The World Health Organization (WHO) is still recommending no international travel restrictions although it is obvious that many countries are disregarding their advice:
https://www.who.int/ith/2019-nCoV_advice_for_international_traffic-rev/en/
"WHO continues to advise against the application of travel or trade restrictions to countries experiencing COVID-19 outbreaks.
In general, evidence shows that restricting the movement of people and goods during public health emergencies is ineffective in most situations and may divert resources from other interventions. Furthermore, restrictions may interrupt needed aid and technical support, may disrupt businesses, and may have negative social and economic effects on the affected countries. However, in certain circumstances, measures that restrict the movement of people may prove temporarily useful, such as in settings with few international connections and limited response capacities.
Travel measures that significantly interfere with international traffic may only be justified at the beginning of an outbreak, as they may allow countries to gain time, even if only a few days, to rapidly implement effective preparedness measures. Such restrictions must be based on a careful risk assessment, be proportionate to the public health risk, be short in duration, and be reconsidered regularly as the situation evolves"