'FULL FORCE TO TEST'Vietnam, virus-free for months, has also had a harsh reminder of the dangers with a new surge spreading to six cities and provinces in six days, linked to an outbreak in the central city of Danang.Authorities told tens of thousands of people who visited Danang to report to disease control centres, as nine new cases were confirmed, taking total infections to 42 since the virus resurfaced at the weekend.Cases have also appeared in the capital, Hanoi, the southern commercial hub of Ho Chi Minh City and in the Central Highlands.Thanks to a centralised quarantine programme and aggressive contact-tracing, Vietnam has registered a total of only 459 cases, with no deaths.But now more than 81,000 people are in quarantine and.