Vietnam – until recently, a rare coronavirus success story – is in the middle of a fresh outbreak that has scientists “stumped”, the BBC reports.

After 99 straight days of no local transmission, cases have suddenly surged in the south east Asian nation – a worrying sign for any country or state that thinks it has the virus under control.

And that includes New Zealand, which yesterday marked its own 99-day run without community transmission.

Remarkably, up until a week ago, Vietnam had yet to record a single death from coronavirus. One week on, the death toll stands at 10.

The country was one of the first in the world to lock down and had reaped the benefit of that strategy. That was even more remarkable because it shares a border with China where Covid-19 was first recorded last year.

But a spike in cases in the central Vietnamese city of Da Nang caught everyone by surprise.

No-one knows how the first case in Da Nang – a 57-year-old man – came into contact with the virus.

There are now almost 800 cases in Vietnam, including in the capital Hanoi and Ho Chi Minh City, otherwise known as Saigon.

Epidemiologist Prof Michael Toole told the BBC it was difficult to pinpoint what “went wrong” with Vietnam’s virus response. Rather, the sudden spike demonstrated something Melburnians know all too well: “once there’s a little crack and the virus gets in it can just spread so quickly”.

Meanwhile here in New Zealand, today marks day 100 of without community transmissionof Covid-19.

The US has recorded 161,906 deaths and is nearing 5 million cases, while the world nears 20 million cases.

John Hopkins University of Medicine recorded Los Angeles has 204,258 confirmed cases and 4919 deaths.

New York City has 23,575 deaths and 227,584 confirmed cases of Covid-19, according to Johns Hopkins.

In a press conference this morning, US President Donald Trump claimed Covid-19 was released into the world “by China”.

-Additional reporting,