The monkeypox virus Photo:VCG

Gene sequencing suggests that the virus strain in the first monkeypox case reported in the Chinese mainland was highly homologous to strains from Germany, according to a report published on Monday by the Chinese Center for Disease Control and Prevention (China CDC) Weekly.

According to the China CDC Weekly report, the case, reported in Southwest China's Chongqing Municipality on Friday, involved a 29-year-old salesman of Chinese nationality. He visited Germany during September 2-8 and had sex with men in Berlin on September 2. He subsequently traveled to Spain, and then returned Chongqing on September 14, 2022.

The man suffered from a dry and itchy throat and had a fever on September 9, with red rashes and pustules on his right ankle. On September 11, he visited a private clinic and took anti-inflammatory medication. On September 14, he was isolated in a COVID-19 quarantine spot in Chongqing. He self-reported that he displayed monkeypox-like clinical manifestations and was then identified as a suspected case of monkeypox by the Chongqing CDC, according to the report. 

Gene sequencing showed that the virus strain in the Chongqing case belongs to the B.1 branch of the West African lineage, and it was highly homologous to strains from Germany collected on June 21, 2022. 

These results confirmed the first imported monkeypox case in the Chinese mainland, making it the fifth confirmed monkeypox infection in humans reported in China. Other imported cases of monkeypox human infections have been reported in Taiwan island and Hong Kong Special Administrative Region, the report noted.

Chinese experts have been warning about the possible occurrence of monkeypox cases in China amid surging cases in the West since May. 

But the disease is unlikely to cause large-scale outbreaks among the public, experts noted, citing China's strict border quarantine measures due to the COVID-19 pandemic. 

The patient was quarantined immediately after arrival in Chongqing, so there is a low risk of virus transmission to local communities, Chongqing authorities announced on Friday. Authorities also noted that close contacts of the patient had all been put under quarantine.

Although a large-scale outbreak is not likely in the short term, there is a high possibility for China to witness sporadic cases, Wu Zunyou, chief epidemiologist of the Chinese Center for Disease Control and Prevention, said Monday on his Sina Weibo account on Monday. 

Foreigners and Chinese nationals returning from places where monkeypox spread are potential transmission origins, especially those from high-risk groups or having close contact with these groups, according to Wu. 

But foreigners who have stayed in China for a long time, and those who have stayed in China for more than 21 days, which is the longest incubation period of monkeypox, pose no risk of virus transmission, Wu noted.

There are two scenarios where monkeypox may spread in China: first, through international monkeypox patients who have close contact with people with the same sexual orientation or living habits as they do; second, through international patients who spread the disease to their families at home, Wu explained. 

Monkeypox is a zoonotic viral disease caused by the monkeypox virus, and historically, all outbreaks have been linked to Africa. However, monkeypox has been posing an alarming challenge to the world in 2022 as approximately 60,000 cases have been reported in more than 100 nations and regions worldwide, read the China CDC Weekly report. 

Many cases of monkeypox were identified in many nonendemic countries outside of Central and West Africa, and human-to-human transmission has occurred frequently, especially among men who have sex with men, presenting new clinical symptoms similar to syphilis and other sexually transmitted infections, according to the report.   

The World Health Organization (WHO) declared monkeypox a Public Health Emergency of International Concern on July 23, 2022. China's health authorities have also issued monkeypox diagnosis and treatment guidelines in July. 

There are three main reasons for the recent outbreak. First, the symptoms were mild and therefore transmission was not controlled in time. Second, monkeypox virus sequences underwent mutations faster than expected during this outbreak. Third, since universal smallpox vaccination programs were discontinued in the 1970s, herd immunity has declined over time, according to an article titled "Preparedness for a Monkeypox Outbreak" published in the Infectious Medicine journal in July authored by Chinese researchers from a state lab under the China CDC.

The researchers warned in the article that global healthcare workers should be on high alert, and the smallpox vaccine may need to be made available in case of an emergency and specific antiviral drugs for monkeypox virus need to be developed immediately. 

Chinese experts have been warning against the occurrence of monkeypox cases in China amid surging cases in the West since May. 

But the disease is unlikely to cause large-scale outbreaks among the public, experts noted, citing China's strict border quarantine measures due to the COVID-19 pandemic. 

The patient was quarantined immediately after arrival in Chongqing, so there is a low risk of virus transmission to local communities, Chongqing authorities announced on Friday. Authorities also noted that close contacts of the patient had all been put under quarantine.

Another important fact is that poxviruses, to which monkeypox virus belongs, are DNA viruses that are easier to control compared with RNA viruses like the SARS-CoV-2, as poxviruses have a stable genome so that they do not mutate that quickly, Zhuang Shilihe, a Guangzhou-based expert on infectious diseases, told the Global Times on Monday.  

Smallpox is so far the only human virus to be eliminated by vaccination because the vaccine is highly effective, Zhuang said, noting that the smallpox vaccine is more than 95 percent effective, and protection lasts almost for life after vaccination.

Because monkeypox virus is closely related to the virus that causes smallpox, the smallpox vaccine can protect people from getting monkeypox. Past data from Africa suggests that the smallpox vaccine is at least 85 percent effective in preventing monkeypox, according to the US CDC.

But mass vaccination against monkeypox is not recommended at present. The US CDC suggests that persons exposed to the monkeypox virus and who have not received the smallpox vaccine within the past 3 years should consider getting vaccinated.