For the past couple of years, as the warm season arrived and another wave of the COVID-19 pandemic ended, everyone expected it to be over soon. But so far, the pandemic has not been curbed due to insufficient herd immunity to the coronavirus. While scientists are convinced that the pandemic will eventually end.
Prof. Aurelija Žvirblienė, a immunologist at the VU Life Sciences Centre, discussed some scenarios for the development of the coronavirus pandemic on the Vilnius University (VU) podcast Mokslas Be Pamokslų.
Virus variants hinder the pandemic management
The current situation with the pandemic in Lithuania is completely different from the autumn of last year, when the country did not yet have vaccines and the only way to control the spread of the virus was through very strict restrictions. Now, according to scientist, we have a two-speed pandemic: cases are less common among vaccinated people and their risk of hospitalisation or death is lower; while the situation among those unvaccinated is more difficult, as the number of cases is high and they are severe. Above all, the hospitals are overcrowded as a result.
Although a large number of people have been immunised this year, the number of people being infected in Lithuania is still higher than in the autumn of 2020. This is due to the emergence of faster-spreading variants of the primary virus, which has certainly complicated the epidemiological situation. “Most of the world is now battling the delta variant, which is spreading several times faster than the original version of the virus. If we did not have vaccines and a large proportion of the population who are vaccinated, that number would be even higher, as we are seeing in those countries with fewer people vaccinated,” Prof. Žvirblienė noted.
The high percentage of vaccinations, especially among the highest risk groups, has helped to contain the pandemic and better manage the situation in Scandinavian countries. “Denmark and Sweden have a very large number of vaccinated older people. Therefore, they can afford to relax the restrictions. Of course, this contributes to the spread of the virus and an increase in the number of cases, but the situation is not critical, as the healthcare system remains stable.”
Immunity curbs the spread of the virus
The survival and extent of the virus are determined by many factors, including the number and frequency of mutations in the virus genome. According to Prof. Žvirblienė, the development of strains of the virus, unfortunately, can neither be predicted nor stopped, as this is a natural process of virus evolution. However, one thing is clear: the more the virus multiplies, the more likely it is that concerning variants will appear.
This is why it is very important for as many people as possible to become immune to the virus. Otherwise, the virus will continue to spread quickly, creating a favourable environment for new mutations that may become increasingly resistant to the available vaccines.
“Of course, the simpler measures, which we are already familiar with, can help slow down the spread of the virus. This includes keeping our distance, wearing masks, limiting contact and being able to work from home. However, these measures will not ultimately solve the problem. Instead, they help postpone a very dangerous scenario. The only thing that really stops the virus from spreading is the number of people who are immune to it,” the immunologist said.
Pandemic development scenarios
According to the immunologist, scientists can only predict how the global pandemic will develop. These predictions depend on how the virus evolves. However, they are certain that a plan to eradicate this virus is impossible and unrealistic.
“The most realistic scenario is that the pandemic will eventually end. Until then, there may continue to be new waves associated with the emergence of new variants of the virus. Last autumn, a major pandemic wave in Europe and Lithuania was linked to the emergence of the alpha variant (from the UK), while the current wave is linked to the delta variant that spread from India. These waves are due to the fact that the new variants of the virus are more contagious, so it produces more copies of the virus, which is spread by the persons infected with it,” the professor explained.
Although scientists cannot predict the mutations of the virus and the associated waves of the pandemic, an increasing percentage of the public will continue to gain immunity, which will allow the pandemic to be suppressed sooner or later.
“The virus is likely to become endemic. That means a virus that circulates in society all the time, causing outbreaks perhaps during each cold season, but people will have to learn to live with that virus just as they do with other circulating viruses. The only problem we need to address is ensuring that those outbreaks do not have tragic consequences. To achieve this, the highest risk groups should be protected as much as possible, which has not yet been achieved in Lithuania,” said the immunologist. She also noted that some people who do not get vaccinated but recover from the disease will also gain immunity, but it will cost a lot – namely, human lives.
Smallpox has completely disappeared due to vaccination
The scientist pointed out that in Lithuania, we have not yet reached the peak of this year’s pandemic wave. She predicts that this may happen in the next few weeks, and after that, the number of cases will start to fall. According to Prof. A. Žvirblienė, the virus will spread more slowly in the coming years, but we will not be able to eradicate it completely.
While there have been cases where the viruses that previously threatened humans have completely disappeared, those cases are truly exceptional. “One such extinct virus, which posed an incomparably greater threat to humans than COVID-19, was smallpox. With the introduction of mass vaccination in the 1980s and its implementation over several decades, smallpox is now extinct. Polio is also close to extinction due to the process of mass vaccination,” the scientist said.
Measles is another example of an endemic virus, the outbreaks of which are stopped by large-scale (over 95%) vaccinations, but as soon as the vaccination rate drops to 90%, measles outbreaks reoccur almost immediately.
“Unfortunately, there are no other ways to fight such viruses – the most versatile weapon we have is the vaccine,” the immunologist noted.