Chinese authorities are facing a new challenge in containing the spread of the Delta variant.

CHINA is back on full alert after detection of the Delta variant.
The mutated variant of the Covid-19 virus had spread to over 20 provinces and municipalities within two weeks.
As of last Friday, the mainland had a total of 2,006 active cases in five high-risk and 150 middle-risk areas.
Authorities are on high alert, warning people against unnecessary travel as millions are placed under quarantine.
Public transport, postal and delivery services, too, have come to a halt in the affected areas. Train services to and fro from 23 cities and towns in these locations have also ceased.
Beijing, known for applying strict measures, has taken action against 18 officials for failing to control the outbreak.
The Chinese capital with an estimated population of 25 million has two middle-risk areas and 22 confirmed cases so far.
Health institutions which are unable to treat Covid-19 patients are not allowed to take in those with fever, according to the municipalitys Health Commission.
They have been instructed to send patients to the respective hospitals using ambulance services instead.
Wear your mask no matter how hot the weather is and cut down on gatherings, reminded Beijing Center for Disease Control and Prevention deputy director Pang Huoxing.
Events like the crowd puller Beijing International Film Festival, scheduled for Aug 13-19, have been postponed.
Many higher educational institutions, which are scheduled to start the new semester on Aug 15, have informed students against returning until further notice.
Teachers and students from kindergartens, primary and secondary schools are required to enter Beijing two weeks before the start of a new school year on Sept 1.
The nationwide outbreak has sparked concerns on whether the China-made vaccines are effective in fending off the more powerful and faster spreading Delta variant.
Chinas top epidemiologist Zhong Nanshan, who has been at the forefront of the countrys fight against the coronavirus since the Wuhan outbreak last year, appeased concerns.
He said preliminary studies found that Chinese vaccines were 100% protective against severe cases based on statistics following the Guangdong outbreak, which was linked to the Delta strain, in May.
Zhong was confident that the outbreak could be brought under control within a few weeks, reported China Daily.
He said the Delta variant had a higher viral load in a persons body and was more contagious.
This has forced the country to redefine the concept of close contact.
The definition of close contact has been expanded to include any person with exposure to a confirmed case in the same room, workplace or building within four days of the onset of symptoms, he told the audience at a conference in the southern Guangdong province recently.
To defeat the pandemic, Zhong emphasised the importance of implementing protective measures in the communities and achieving herd immunity.
He pointed out that the country needed to vaccinate at least 83% of the population to achieve herd immunity.
So far, 1.72 billion doses of vaccines have been administrated.
China has administered the most vaccine doses in the world but the proportion per 100 people is still low because of the huge population, he explained.
This round of pandemic started in Nanjing city, Jiangsu province, where a cleaner contracted the virus after cleaning a plane from Russia at Nanjing Lukou Airport last month.
The virus quickly spread to other airport workers and eventually reached Zhangjiajie, Hunan province, a popular tourist destination that housed the Meili Xiangxi Grand Theatre.
The theatre, that ran three to four performances per day, catered to about 2,000 audience per show.
Infected travellers then carried the virus back to their respective homes, triggering widespread infection of the Delta-chain.
Zhangjiajie gained the nickname Home of Avatar after award-winning film director James Cameron created the Hallelujah Mountains of Pandora in his blockbuster Avatar based on the citys mountain range.
China is under pressure to control and contain the pandemic prior to the 2022 Winter Olympics, scheduled for Feb 4-20 in Beijing.
Just as it began its race against time to trace and contain the spreading chain, however, another outbreak was reported in Zhengzhou, Henan province.
The source was said to be from a hospital where a patient was admitted.
Henan was hit by major floods last month, resulting in 302 deaths. Fifty people were also reported missing and more than 14 million made homeless.
A rise of cases in Wuhan was also recorded after the new pneumonia virus was first detected in January last year. This had resulted in a lockdown of the city.
Meanwhile, Chinese vaccine developers announced that they were gearing up to develop vaccines targeting the new Delta variant.
As of last month, the National Medical Products Administration approved 22 types of Covid-19 vaccines using five technologies for clinical trials.
Four have obtained conditional approval while three have been given the green light for emergency use.