"The pandemic is gradually turning into an endemic situation due to immunization. I imagine that if nothing changes, we can probably expect that all the restrictions associated with the pandemic will no longer apply next year, because the health care systems will no longer be threatened – people will either be vaccinated or will have recovered from contracting the virus", A virus researcher, VU Life Sciences Centre researcher Dr. Gytis Dudas, predicts on the Vilnius University (VU) podcast "Science without Sermons". At the same time, however, one fact is worrying the researchers – the particularly wide range of SARS-CoV-2 hosts.
In the show, the interlocutor talks about how the coronavirus, which started spreading from China, has evolved, how long, according to historical data, a virus-induced pandemic lasts, what kind of pandemic cycle we are in right now and what we can expect in the future.
Original coronavirus variant is no longer present
According to the virus researcher, the onset of this pandemic could have been predicted for a long time. That is because the scientists knew in advance that something similar to coronaviruses could happen, they just did not know when and under what circumstances it would happen. According to him, a lot of research has been done in the last few years in order to find coronaviruses in Chinese bats, because that is where the greatest diversity of these animal species is, which means that the largest variety of coronaviruses is also circulating in their bodies. Viruses that infect bats are extremely common in other species and cause many problems.
Now, we could probably no longer find anywhere in the world the original variant of the SARS-CoV-2 virus that has spread around the world from China, as the virus is constantly evolving. “Any living organism, in making its own replications, must first replicate its genetic material, and the proteins that perform that replication function are not infallible, therefore, errors occur during the replication of any organism, which are called mutations. "When the coronavirus spread around the world, there were errors, and those errors were inherited from the offspring of the virus," says the interviewee.
Truth be told, the virus, which was detected in Wuhan, was still found unchanged in some countries until April 2020. But later that genotype disappeared and the offspring, who already had some changes, became dominant in the world. And quite late in the course of the whole pandemic, various strains of concern emerged, which the World Health Organisation (WHO) began to call the letters of the Greek alphabet.
Over a thousand strains
In the nearly two years since the virus spread, more than a thousand new strains of the virus have been detected and named, however, only a few have received special attention. The interlocutor distinguishes three such strains that have significantly altered the course of the pandemic: alpha (with an increased transmission advantage), delta that has spread twice as fast as the original strain, and omicron, which, according to early data of the scientists, is significantly antigenically advanced, which means that for the human immune system, when familiar with any other strain or vaccine against this virus, omicron appears to be quite different and the immune system fails to prevent infection.
The scientist says that the number of strains of coronavirus cannot be defined by the number of letters of the Greek alphabet, so this methodology was chosen to mark only the strains of concern. All emerging new SARS-CoV-2 sequences were classified using the Pango nomenclature, which is designed to reflect an unlimited number of strains. According to it, the names of new virus variants consist of a combination of letters and numbers (e.g. B.1, B.1.620, B.1.1.7) where the letter indicates from which primary strain the new strain evolved, and the number indicates the origin of the new strain.
Researchers hope that the virus will soon take on a more stable shape, change less and become endemic. "Judging by the immunisation alone, we are already moving towards the end of the pandemic. If we look at the historical data, the pandemic period that is most troubling is usually about two years. Pandemics gradually enter the endemic phase precisely because of the immunisation process. At the end of the pandemic, the pathogens that caused it no longer cause so much trouble for health systems, as a certain kind of balance in the population occurs – people no longer become infected at the same time.”
Will the pandemic end next year?
Dudas predicts that if we talk about the current situation and nothing changes in it, we could, potentially next year, expect that all the restrictions linked to the pandemic would no longer apply, as the threat to health systems would no longer exist. However, a very important aspect that worries many scientists is the SARS-CoV-2 virus's wide range of hosts.
"A great example of this was the outbreak of the virus on fabric farms in Europe, as well as the prevalence among white-tailed deer in the United States of America. It is believed that rodents can also be infected with this virus. When the virus jumps into these reservoirs, the virus, after adapting to the new host, continues to spread in their bodies and then re-infect humans. We have a similar situation with Omikron, whose origins are also linked to the animal reservoir,” explains the virus researcher.
Therefore, according to Dudas, it is quite possible that 10-20 years after coronaviruses circulating in a new host will acquire different antigenic traits, will be able to infect people born after so many years who have never been exposed to such a version of the SARS-CoV-2 virus. Theoretically, they would be susceptible to it and this would once again threaten the occurrence of a large-scale contraction of diseases.
Which host is most favourable for the virus?
When asked what determines in which host the virus will function most effectively, the scientist says it is very difficult to predict that, as it can depend on many components and sometimes – just one favourable factor that makes that host unique in spreading the virus.
As an example, the interlocutor cites the use of martens, specifically ferrets, for influenza studies, for which they are perfectly suited due to the similarity of the airways of these animals to humans and their susceptibility to the virus.
In the case of the MERS virus, which was first detected in 2012, it circulated well in the bodies of camels, which are considered to be farmed animals on the Arabian Peninsula, however, despite the fact that people have been infected with the MERS virus from the camels thousands of times, they have not been able to transmit the virus to other people and as a result of this, the outbreak of this virus did not take place 9 years ago.
There is another problem besides the pandemic
When asked which viruses and regions are now the most troubling to the scientists, what awaits us after the coronavirus, Dudas says the most likely other pandemic that could hit the world will be the flu, as we have to face them very often. It can occur anywhere, where pigs are raised and where migratory birds are present.
"As for other viruses, the biggest risk is always where there is the most diversity, such as the tropics, the jungle, or the places we invade with our human activities (mining, illegal logging, living very close to the wild, traveling around the world), which create favourable conditions for the spikes in the spread of the virus.
Among the most threatening groups of viruses, the researcher cites the same coronaviruses, but says there are several other viruses, such as Nipa (in India), that are more concerning in regards to the severity of the disease caused than its wider spread.
However, the researcher is concerned not only about viruses. According to him, in addition to the pandemics they cause, we have another big problem – climate change. Global warming also means that carriers of disease, such as mosquitoes and ticks, can expand their living areas and thus, for the first time since medieval times in Lithuania, we could develop malaria or other mosquito-borne diseases.
"There are a lot of challenges ahead, and the only thing we can do is prepare for them. "Attention should be paid to the early detection of primary cases, more attention and expertise in virus sequencing should be paid around the world, and it should be ensured that all countries have convenient access to sequencing infrastructure and regents," advises Dudas.