The Lancet is the first to assess the impact of travel restrictions on the outbreak

BEIJING, Dec. 23 (Xinhua Zhang Mengran) The British Lancet Public Health magazine recently published a study, the first assessment of travel restrictions on the global impact of the epidemic, the results show that only targeted implementation of international travel restrictions can effectively control the spread of the new coronavirus.
by the end of April 2020, countries around the world had paid high economic and social costs, treating different forms of travel restrictions as part of initiatives to control the spread of the virus and implementing the policy to varying degrees. To date, however, no studies have made a global estimate of the relationship between the risk of imported cases and the level of community transmission of the virus. Today's new findings could provide policymakers with evidence to determine where travel restrictions can slow the spread of the virus in communities and where they have had little effect.
This time, a team led by Mark Kite, a scientist at the London School of Hygiene and Tropical Medicine, compared the number of expected imported cases of the new coronavirus on international flights (assuming there are no travel restrictions) with the number of infections caused by virus transmission within the country by reference to detailed flight data, and estimated the number of international passengers in May and September 2020 based on two scenarios. In the first case, assuming that the number of passengers did not decrease, flight data for the same month in 2019 were used; Using a mathematical model that added asymptomatic and unresolted infections to the number of recorded cases, the team adjusted to estimate the actual number of cases and infection rates of new coronavirus infections.
Thus, this conclusion is based on the way in which imported cases of the new coronavirus affect the growth rate of community outbreaks, showing that in some countries, imported cases account for more than 10 per cent of the total number of cases in the country, then imported cases will significantly affect the growth of the epidemic in the country; This is because imported cases can lead to outbreaks in countries where there are few or no existing cases.
," said the study made them aware that because of the high economic and social costs of such measures, the government needed to introduce targeted travel restrictions. Before implementing these restrictions, governments should take into account factors such as the number of local infections, the rate of outbreak growth and the number of visitors from countries severely affected by the virus.
concluded that restrictions on international travel should not be general. Countries must first consider the number of indigenous infections and the rate of increase in outbreaks, as well as the number of visitors from countries severely affected by the new crown outbreak. As an example, the article says that in September 2020, as New Zealand and China have enough to keep the virus at a fairly low level, and the expected number of imported cases is similar to the actual proportion of natives, new arrivals will likely trigger a new wave of home-grown infections, so the move will work in both countries.