Old Version

Fighting the Variants

The first cases of the Delta variant in southern China prompted even tougher quarantine and testing interventions

By NewsChina Updated Sept.1

People line up for nucleic acid tests, Foshan, Guangdong Province, June 5

On May 21, a 75-year-old woman surnamed Guo was confirmed positive with the Delta variant of the virus that causes Covid-19. It was followed by confirmation of over 100 new emerging community cases in Guangzhou, capital of South China’s Guangdong Province, in the following month.  

Guo felt unwell on May 18. She took some medicine, but two days later on May 20, she walked to her local hospital in Liwan District and tested positive that night.  

The World Health Organization (WHO) declared the Delta or B.1.617.2 variant of SARS-CoV-2 as a Variant of Concern on May 11. It was detected in India in October 2020, and was responsible for the second wave that swept the subcontinent in early 2021. It had spread to 104 countries by July 4, media reported.  

Mass testing was conducted in areas related to Guo’s case by May 23 with 12,800 samples collected. By May 25, only one more related asymptomatic Covid infection case, Guo’s husband, was confirmed. But it was not the end of the outbreak. By June 19, Guangzhou reported 153 positive cases and seven asymptomatic ones.  

An expert from the Chinese Center for Disease Control and Prevention (China CDC) told NewsChina on condition of anonymity in early June that considering the incubation period, mass nucleic acid testing could not identify everyone who was infected, so there would be more cases identified two weeks from the first infections.  

The new outbreak in Guangzhou, as well as in other cities including Foshan and Shenzhen, put the country back on alert. Given China’s strict border closures and quarantine systems, it is not yet known how the Delta variant, which would have been imported, formed a community infection cluster, nor who the source of the infection was or where. At the same time, Guangzhou failed to identify and cut off transmission before the virus spread within the community.  

High Transmission 
The new variant is more infectious, and it spread for five generations in just two weeks in Guangzhou.  

Two days after Guo tested positive, her husband was diagnosed as an asymptomatic carrier. On May 25, an employee of a dim-sum restaurant where Guo had eaten tested positive. The next day, four new cases related to Guo were found, who had either dined at the same restaurant or were related to them.  

By May 28, Liwan District had tested all residents. Six key areas within the district were listed as high risk and put under strict pandemic controls. Jiang Qingmei, an epidemiologist and former dean of the School of Public Health at Fudan University, told NewsChina that despite the new cluster of cases, he was optimistic because, in his opinion, Guangzhou has better medical facilities and trained healthcare workers than many other places in China.  

Despite the rapid testing and quarantine measures, the outbreak was not contained. On May 29, 12 asymptomatic cases were reported and by the beginning of June, new cases were being reported daily.  

Gene sequencing found that Guo was infected with the Delta variant. She had not traveled to medium- or high-risk areas in China nor had contact with people that had been overseas in the preceding months. She had not left Guangzhou in the 14 days before she got infected. According to official information, preliminary research found that Guo was exposed to someone who had been infected overseas.  

“This indicates the virus was spreading silently for some time, but it was Guo who first showed symptoms, and then was spotted,” Jin Dongyan, a virology expert at the University of Hong Kong, told NewsChina.  

Experts noticed that as the virus spread within the community, there were cases that were not related to the chain of transmission of existing cases, and there was a “super spreader,” an asymptomatic woman in Liwan District who had infected up to 19 people by June 3.  

According to Jin, a person who spreads the virus to over 100 people is considered a super spreader, and one who spreads it to more than 10 can be categorized as a minor super spreader. “As soon as we get super spreader cases, infections are amplified quickly. This is the kind of situation that we make a top priority for prevention and control,” Jin said.  

Other random cases started showing up in community fever clinics in Liwan District in early June. Public health experts and staff members from disease control systems noticed that the viral transmission was strong with a high virus load. “The virus is easily transmissible just [in the time it takes for] one meal or a short period of indirect contact,” said Zhang Zhoubin, deputy director of the Guangzhou Center for Disease Control and Prevention (Guangzhou CDC), at a press conference on May 31.  

Chief expert Cai Weiping from Guangzhou No.8 People’s Hospital, a designated coronavirus center, told NewsChina: “From what I learned, many infected people in Hainan Village in Liwan District had not dined together or gathered for mass activities, and some cases connected to Guo did not have direct contact with her in the same restaurant.” According to Cai, the virus had spread for at least five generations in Guangzhou. He said that hospitals monitoring patients’ viral load found it was no different from the first and second generations, which indicates the transmission capacity of the new variant does not deteriorate, thus the new variant is more infectious than the predominant strain of Covid-19 in 2020.  

Lei Chunliang, president of Guangzhou No.8 People’s Hospital, told the Guangzhou Daily that apart from high transmissibility, in patients infected with the Delta variant, the incubation period was shorter and they became sicker. Four of the patients there had one shot of a vaccine, and the others were not vaccinated. 
Yang Zhicong, director of the Guangzhou CDC, said the median incubation period was only 3.2 days, significantly shorter than the 5.9 days reported in previous studies, and the shortest incubation period so far was less than 24 hours, indicating the new variant spreads fast. 
The R number of a virus is an indicator of how contagious a disease is and how many people it infects. The average R number of the coronavirus was two to 3.2 in China, but from May 25 to its peak on May 29, the number increased to 6.06 in the Guangdong outbreak.  

“The Delta variant spread rapidly, with an average incubation period of two to four days and a large viral load, and so community spread developed quickly,” Zhang Zhoubin.  

Upgrading Intervention 
The spillover of the Delta variant worsened the pandemic in many countries near India in South and Southeast Asia. Even after strengthening border controls and restricting passenger flows, it is hard for any country to keep the virus completely out.  

China faces similar challenges, and there have been previous smallscale outbreaks in many of the country’s border and port cities, including Ruili, on the border of Myanmar and Southwest China’s Yunnan Province, and the eastern seaports of Qingdao and Dalian.  

On July 7, a new outbreak in Ruili prompted a new round of citywide testing and a lockdown, with more than 100 positive cases detected, including imported cases and community infections. 

But Guangzhou, the biggest entry-exit port for passengers returning to the Chinese mainland, bears the brunt of the threat. On May 20, Duan Yufei, director of the Guangdong Provincial Health Commission, said that Guangdong receives 90 percent of all inbound travelers entering the country every day. There are over 300 designated quarantine venues in the province, and nearly 30,000 people are in some stage of quarantine every day with nearly 20,000 staff working at quarantine sites.  

In late June, Guangzhou announced it would construct a 5,000-person temporary quarantine center for international arrivals to cope with more infectious variants like Delta. It is expected to open in September.  

In 2020, Guangzhou Baiyun International Airport surpassed Hartsfield-Jackson Atlanta International Airport in the US to become the world’s busiest airport with the largest passenger capacity. Since October 2020, three asymptomatic infected people or patients that had recovered from Covid-19 subsequently tested positive in Huadu, Nansha and Haizhu districts of Guangzhou, two workers in quarantine hotels and a Chinese national that had traveled from the UK.  

Wei Sheng, a professor at the Department of Epidemiology and Health Statistics of the School of Public Health, Tongji Medical School of Huazhong University of Science and Technology, told NewsChina that Guangdong is unique in its prevention and control of import-related infections because it receives 90 percent of inbound arrivals. The city’s closed-loop management efforts for inbound passengers involves many departments and stages, so managing it and controlling the risks is complex.  

Addressing the pressure of rising imported infection cases, the already strict border policy was tightened even more. It already includes restrictions on flights, bans on direct flights to some countries, while it has been hard for most non-Chinese nationals to enter the country for well over a year, including overseas students.  

The China CDC announced on May 14 that in addition to the required 14-days quarantine for entry for people from outside the Chinese mainland, people coming from overseas must also provide two nasopharyngeal swab samples with two different nucleic acid testing reagents and obtain two testing reports from different agencies before they can be released from quarantine. 

After release from quarantine, people must undergo two nucleic acid tests on the second and seventh day. Requirements are even stricter in some parts of China, including Beijing, with extended periods of monitoring and quarantine lasting 21 or even 28 days.  

On June 5, nine new infections were reported in Guangzhou, six in the same family, the Zhangs, who live in Guangzhou’s Nansha District. The husband and wife had dined in a restaurant in Liwan District where a confirmed case had been.  

Nansha District started testing all residents on June 4, which revealed a few new cases. When the couple returned to their home in Nansha from Liwan, the area had not yet imposed any lockdown restrictions. The Zhangs were busy, visiting many places including restaurants, a kindergarten and a chess club. The family’s infection meant a new outbreak had started unnoticed within the wider community.  

The Zhang family case triggered a sudden escalation of prevention and control measures. From the afternoon of June 5, urban buses, subways, ferries and long-distance buses were stopped, residents were encouraged to not leave the district and expressways and high-speed railways and docks were temporarily shut down. The lockdown measures in Nansha were much stricter than in Liwan.  

On May 29, Huang Guanglie, director of the Guangzhou Municipal Health Commission, described the situation during a press conference: “We must run a little earlier and faster to stop the transmission of the virus and cut the chain of infection, otherwise, there is a high chance of more local infections.”  

An epidemiologist from the China CDC told NewsChina that implementing prevention and control measures within a limited scale while controlling an outbreak is a challenge that will test the ability of local officials. He said that a megacity like Guangzhou, with more than 18 million permanent residents, is so densely populated and economically active that it is difficult for the local government to decide to what degree to enforce prevention and control measures, since there is a consequent economic impact. In Guangzhou, as the outbreak continued, there was a continued ramping up of testing and lockdown measures.  

Tightened control measures at transportation hubs since the end of May resulted in a drop of more than 60 percent in daily passenger trips in Guangzhou. Starting June 7, people in areas deemed medium or high risk were not allowed to leave their homes.  

In early June, other city districts also conducted nucleic acid testing for all residents.  

“We emphasized targeted prevention measures, but as we are countered by such a rapid transmission of the Delta variant, we must set up in advance prevention and control measures. So largescale nucleic acid screening is very effective and very necessary,” said Zhang Zhoubin during an interview with Central China Television. According to Zhang, since the start of mass nucleic acid screening on May 26, as of June 5, more than 16 million test samples were collected in Guangzhou, with 33 positive results.  

On May 30, the R number decreased to 4.19. Yang Zhicong, director of the Guangzhou CDC, said the effect of the mass testing in Guangzhou was significant. “We calculated through mathematical models that without effective prevention and control measures, there would be nearly 300 cases.”  

Unlike the SARS epidemic in 2003, which spread and was contained within months, the fight against Covid-19 is a prolonged battle. “We must have zero tolerance towards sporadic outbreaks and the spread of mild infections,” Zhang Wenhong, professor and head of the Center for Infectious Disease, Huashan Hospital of Fudan University in Shanghai, told media on June 3 during the Boao Forum for Global Health for Asia.  

Zhang pointed out that only when the vaccination rate in China is high enough can the country get sufficient data, including the duration of the vaccine protection rate and the resistance of the vaccine against imported infections. When China’s existing medical network can resist sporadic cases and can control the Covid-19 mortality rate and morbidity to a very low level, then the country can talk about relaxation of current intervention measures, Zhang said. 
Feng Zijian, a researcher at the China CDC, said at the same forum that the only goal at the moment is to have all people vaccinated as quickly as possible. “It’s the safest way, and then we can have the conditions to consider adjusting our strategy,” Feng said.  

Given a jolt by the recent outbreak, vaccination in Guangdong Province, with a population of more than 180 million, has accelerated. Data on June 2 indicated that 60 million doses had been administered in Guangdong. It took Guangdong 108 days to fulfill the first 10 million doses, and 26 days for the second 10 million doses, 13 days for the third 10 million doses, and a mere six days for the sixth batch of 10 million doses. As of June 2, vaccination coverage of the target population between ages 18 to 59 in major cities in Guangdong, including Guangzhou, Shenzhen, Foshan and Dongguan, had exceeded 70 percent for the first dose.  

While the vaccine campaign was slow to start in China, efforts to vaccinate the population have ramped up, particularly after the recent outbreaks, with many previously hesitant people flocking to vaccination centers. As of July 13, across China, over 1.4 billion doses of Covid-19 vaccine have been administered.