Much of the region escaped the pandemic’s first wave last year relatively unscathed by rapidly closing borders and introducing curbs.
But countries from Thailand to Vietnam are being hammered by fresh surges, with efforts to quell outbreaks hampered by slow vaccine rollouts and populations weary of restrictions.
Malaysia is among the worst hit. Of almost 2,800 deaths from COVID-19 recorded in the country of 32 million since the start of the pandemic, over 40% were in May alone.
More than 570,000 infections have been reported, with a string of new daily records last week.
As well as variants, the outbreak has been fanned by gatherings in the Muslim-majority country during the holy month of Ramadan and the Eid al-Fitr holiday, often in defiance of coronavirus rules.
Under what authorities have termed a “total lockdown” in force from today, only essential businesses - such as supermarkets and medical clinics - can operate, people can only go outside for necessities, and most schools are closed.
Travel between most parts of the country had already been banned for months.
While there had been growing calls for tougher action, the lockdown will deal a fresh blow to many businesses that have struggled to stay afloat over the past year.
“The impact of the coronavirus on small businesses like mine is devastating,” said Lilian Chua, whose hair salon outside the capital Kuala Lumpur will have to close.
“The government imposes a lockdown but the virus is in the air -- they need to speed up vaccinations,” the 42-year-old told AFP.
Fewer than six percent of Malaysia’s population have so far received at least one vaccine dose.
Slow vaccine rollouts
Vietnam was praised for keeping infections low last year, but its cases have more than doubled in the past month, prompting officials to suspend foreign arrivals at some airports and implement social distancing in Ho Chi Minh City.
At the weekend, authorities caused alarm by announcing they had discovered a new variant which is a combination of the strains first detected in Britain and India - although they later clarified it still needs to be studied.
Overcrowded prisons have been at the centre of an escalating outbreak in Thailand, which is recording more than 4,000 infections a day.
Affluent Singapore - which had barely seen any local transmission for months - tightened curbs in May following an uptick in cases, with authorities citing concerns about variants.
And the Philippines imposed a fresh lockdown in and around Manila in March as hospitals struggled to cope, although the restrictions have been eased as infections fall.
Infection rates have been relatively stable recently in Indonesia, however, which was hit hard last year at the start of the pandemic.