The explosion of COVID infections in China since it relaxed its prevention and control measures has experts weighing the risks of new mutations that could prove to be more contagious or deadly that the currently dominant omicron strain.
According to an internal estimate from China's top health officials reported by Bloomberg and the Financial Times, almost 250 million people in China may have caught COVID-19 in the first 20 days of December.
Ziyad Al-Aly, director of the Clinical Epidemiology Center at Washington University in St. Louis, told VOA Mandarin that infections are likely to soar further as millions of Chinese travel for the lunar New Year in just a few weeks.
A model from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington School of Medicine forecasts a major omicron epidemic to unfold in the coming months. The model shows that in the absence of renewed lockdowns and other stiff measures, the daily estimated infections could rise to 4.6 million by March 1, 2023.
Experts say the unprecedented surge increases the probability of a new virus mutation taking hold.
"When a virus is widely circulating in a population and causing many infections, the likelihood of the virus mutating increases," the World Health Organization explained on its website last year. "The more opportunities a virus has to spread, the more it replicates – and the more opportunities it has to undergo changes."
Al-Aly said that every time someone is infected, the virus has an opportunity to mutate, so an explosive increase in cases will undoubtedly increase the possibility of new mutations.
"We have not seen it yet, but that probability really is increasing dramatically now, just because the number of infections is exploding really, really quickly in a very, very short amount of time," he said.
Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston, also believes that the surge of cases in China is likely to prompt the emergence of new mutations.
"The unchecked spread of COVID among a large unvaccinated or under-vaccinated population in China could do this (promote new variants). Similar to the emergence of Delta among an unvaccinated population in India in early 2021," he said in a tweet.
The mutated strain, delta, first discovered in India in October 2020, is considered to be one of the driving factors of the second wave of the epidemic in India. Last year, it became the main epidemic strain in more than 100 countries.
According to Bloomberg, Chinese authorities submitted 25 new genetic samples taken in the past month from Beijing, Inner Mongolia and Guangzhou to GISAID, a database where scientists from around the world share coronavirus sequences to monitor mutations. Peter Bogner, chief executive officer of GISAID, said there is so far no sign suggesting any new variant of any significance.
Past mutations led to the emergence of omicron, which is less lethal than earlier versions but spreads very easily, as the dominant strain. But there is no guarantee that a future mutation might not cause more severe illness and deaths.
A study last month by a team of scientists from Africa Health Research Institute in Durban addressed that possibility. This study has not yet been peer-reviewed.
In an email to VOA Mandarin, Alex Sigal, the leading scientist of study and a faculty member at the Africa Health Research Institute and associate professor at the University of KwaZulu-Natal, said, "Our study showed there is a possibility that a more pathogenic variant may arise based on viral evolution in someone who was immunosuppressed. Whether such a variant will actually emerge is unclear."
Because China was able to minimize the number of infections over the past three years with its zero-COVID policy, its population has less natural immunity than in other countries where omicron has become dominant because of its ability to evade immunity.
Sigal said because of that, other variants will find it easier to compete against omicron in China, raising the chances of a new strain becoming dominant.
However, Sigal said, "Omicron subvariants are also extremely good at replication and transmission. Therefore, the most likely scenario is that they will still outcompete any completely new variants, and it will be more of what we know – infections which are mostly unpleasant but not as dangerous since they tend not to spread to the lungs."
Jin Dong-Yan, virologist in the University of Hong Kong's Department of Biochemistry, noted that China's vaccination rate is 90%, although the Chinese vaccines are not as effective as some of those developed elsewhere. Nevertheless, in an email to VOA Mandarin, he said he sees a low risk of new variants emerging and even if one does, it "will most probably be less virulent or dangerous."
David Dowdy, an infectious-disease epidemiologist at Johns Hopkins, told VOA Mandarin in an email, "On a single country basis, the current COVID wave in China might be the biggest we have ever seen. But on a global basis, the omicron wave last winter was certainly bigger. Meaning, there is certainly a risk of a new variant emerging during this wave, sparking a global outbreak. But thanks to global levels of immunity, that risk is lower than it might have been a year or more ago."
Adrianna Zhang contributed to this report.
