As Covid-19 vaccination gains momentum in the developed world, the question of what comes next is becoming increasingly relevant. Will all borders finally be opened, and to what extent will the emergence of new coronavirus variants hinder this? How far away are we from herd immunity, and will the world be able to return to normal life before an effective treatment for coronavirus is found?
The Russian service of the BBC talks about the main possible scenarios for ending the pandemic and which of them scientists consider the most likely. At the end of July, the Lancet published an article written by thirty leading European medical scientists reflecting on the possible direction in which the Covid-19 pandemic may develop in the coming months and years. The main question posed by the authors of the article is whether the pandemic will end, at least within the next three to five years. According to European experts, this will depend on three main factors:
As of today, the authors note that the state of affairs in all these areas does not look very optimistic.
According to researchers, people around the world are becoming less willing to comply with anti-COVID restrictions. Only one in four adult inhabitants of the planet has received the two required doses of the vaccine – and it is not just a question of unavailability of medicines, but also a lack of confidence in them. The highly contagious virus strain “Delta” has already invaded almost all countries, gradually displacing its less dangerous counterparts and, most unpleasantly, often infecting those who have already recovered or have been fully vaccinated against Covid-19. At the same time, according to the authors of the article, restrictive measures are being observed around the world and, worst of all, they are getting worse. Under these conditions, it is not surprising that the number of new infections continues to rise rapidly. Statistics show that the world is at the peak of the third wave of the pandemic: since mid-July, the number of confirmed diagnoses has increased by more than one and a half times (from 350 to 655 thousand per day).
The course of the pandemic, including the number of cases, will also depend on whether a cure is found for the disease and its long-lasting form, known as “long COVID”. In a brief description of possible scenarios for ending the pandemic, the authors of the article are hesitant to say with certainty whether Covid-19 will pose a serious health threat in the long term. On the one hand, they acknowledge that a complete eradication of the virus is unlikely: even if all COVID patients recover, the infection will continue to spread among animals, where it may mutate in unexpected ways. On the other hand, much depends on how quickly an effective drug is found – not only for the disease itself, but also to combat the prolonged form of the infection, better known as “long COVID”. An article published in the Journal of the American Medical Association (JAMA) at the end of July details possible scenarios for the development of the pandemic. “The large-scale vaccination campaign (which is rapidly gaining momentum in the United States) offers hope for a relatively rapid return to normal life,” the authors write. “However, there are many obstacles in the way: extremely uneven vaccine availability, persistent vaccine resistance, the emergence of new variants of the virus, and global waves of deadly infections,” they add.
The smallpox virus was successfully eradicated in the late 1970s. The four possible scenarios described in the study “represent a spectrum of possible outcomes that could resolve the Covid-19 epidemic. Scenario One – Total Eradication. This scenario assumes that doctors will be able to wipe Covid-19 off the face of the earth, as they did with the natural smallpox virus nearly half a century ago. We explain quickly, simply, and clearly what happened, why it matters, and what happens next. Episodes The end of the story: Promotional Podcasts. However, this success can only be repeated under one condition. Immunity (both post-vaccination and post-overcome) must be strong and long-lasting to protect against re-infection while preventing further transmission of the infection. In the case of Covid-19, there is little hope – given the virus’s ongoing mutations, the option of eliminating it completely “may be too ambitious even as a mental experiment, let alone as the basis of a health strategy. A more realistic short-term goal, the authors say, is elimination, which means temporarily reducing the number of infections in a given country to zero through mass vaccination and strict containment measures – essentially a complete closure of borders and isolation from the outside world. The best known example of this to date is the situation with the measles virus. Thanks to mass childhood vaccination, outbreaks of this disease are now rare and can be brought under control relatively quickly. In the case of the coronavirus, it was possible for a while to achieve this in several countries: Australia, Vietnam, China, New Zealand and Singapore. As the authors of the study write, this option is most likely in the event that the epidemic needs to be kept under control by periodically updating the vaccination.
The worst situation with vaccination is in poor countries, and until they manage to vaccinate their populations, the virus will continue to spread across the planet. The third scenario – living with the virus (cohabitation) – assumes that the developed vaccines (or their future modifications) will continue to protect only against severe cases of Covid-19 and fatal outcomes. Under such conditions, where there are many vaccinated individuals, the virus will no longer pose a lethal threat, and Covid-19 will essentially turn into a seasonal cold. Of course, sometimes even vaccinated people will get sick – due to a decrease in their overall immunity, a natural decline in antibody levels over time, or new mutations of the virus. At any given time, however, a large proportion of the population will be sufficiently protected to prevent large-scale outbreaks of serious disease. Finally, the fourth scenario is a large-scale conflagration. This option is most likely if a significant portion of the population remains unvaccinated, whether because of vaccine availability issues, medical contraindications, low immune status, or simply personal reluctance. In this case, the virus will continue to spread rapidly – and mutate as a result. Experts believe the third option is the most likely in the long term. For now, however, the pandemic is likely to evolve according to the latest scenario, even though there are not many vaccinated people. “In terms of the planet, the number of vaccinated people is still very small,” Eli Adashi, a senior author in JAMA and a professor at Brown University, tells the BBC Russian Service. “And that means the virus can spread freely around the world and mutate as much as it wants.”
Most licensed vaccines with high efficacy protect against severe disease progression, but not always against infection. Professor Paul Hunter of the Norwich Medical School at the University of East Anglia, who was not involved in the study, also does not believe in the possibility of complete eradication of the infection. He points out that the natural smallpox mentioned in both studies is a virus that leaves a persistent – also called sterilizing – immunity. And according to recent data, immune protection against the new coronavirus declines by about half within six to nine months. In addition, currently licensed vaccines with varying degrees of effectiveness prevent severe cases of Covid-19, but do not necessarily protect against infection: there are many known cases of fully vaccinated individuals still becoming ill. The disease may progress relatively easily or even asymptomatically in these individuals, but they can still spread the virus and infect others. This is why the herd immunity that the majority of scientists (and consequently politicians) hoped for at the beginning of the pandemic ultimately proved unattainable. “If there is no sterilizing protection and the virus continues to spread, you will not be able to protect those who do not have immunity – explains Professor Hunter. They will still be infected one way or another, so herd immunity is impossible in this case. “So it is not possible for us to eradicate the virus. It is also unlikely that we can contain it within certain geographical boundaries,” continues Paul Hunter. “As for a large scale outbreak, this option should not be perceived as if the virus will inevitably mutate at some point and decide to kill us all. In my opinion, this is very unlikely – I would say virtually impossible”. “Most likely, the virus will become seasonal and we will be infected periodically throughout our lives. This conclusion has already been reached by virtually all the world’s leading virologists,” he concludes. In January, the journal Nature conducted a survey of scientists – immunologists, virologists, and infectious disease specialists from around the world – collecting more than a hundred expert opinions. Nearly 90% of respondents agree with Professor Hunter: it will not be possible to completely eradicate the Sars-Cov-2 coronavirus, and it will continue to infect people periodically around the world. At the same time, children who have had the disease at an early age will develop stronger immunity than adults, along with partial protection against future virus mutations.
Perhaps we are facing a kind of “arms race” between vaccines and new viral mutations. Less than 40% of the experts surveyed believe that it will be possible to control (eliminate) the Covid-19 epidemic, at least in certain regions. “All we have are vaccines and restrictive measures, and each person decides how strictly to follow them,” says the lead author of the JAMA article, Professor Eli Adashi. In addition, because immune protection wanes fairly quickly, it is likely that the vaccine will need to be updated periodically. “What if new variants emerge against which existing vaccines provide significantly less protection? In that case, a kind of arms race [between the virus and vaccine developers] could start,” says Professor Adashi. “New drugs will be constantly catching up with the mutating virus. And whether we have a chance to win this race is still unclear.” However, the expert adds that in addition to the four options already described, there is a fifth scenario – the most optimistic. It is based on the assumption that doctors will be able to develop an effective antiviral drug or find another treatment option for Covid-19 in the foreseeable future. Such developments are happening, Professor Adashi notes. The U.S. government has already signed a contract to buy two promising antiviral drugs. Both are currently in the final stages of clinical trials and have not yet been given official names (documents refer to them by the code names AZD7442 and MK4482), but in theory they could have a significant impact on the course of the pandemic. Of course, both drugs still need to prove their efficacy and receive regulatory approval. However, Professor Adashi says he is placing his greatest hope in the development of a drug against Covid-19. “In the foreseeable future, the only thing that can get us out of the current situation is an antiviral drug,” he says confidently.
Will we be able to travel with the same ease as before? Scientists have no answer. Mike Ryan, executive director of WHO’s health emergencies program, says he himself would like to know when the pandemic will end. But a doctor should always tell patients the truth, and the truth is that no one knows the answer to that question at this time. “What I know for sure is that it will end sooner if each of us does something,” he says confidently. “If we give vaccines more opportunities to be administered around the world. If we think about how to protect ourselves and those around us. If we make our hospitals better at helping the sick. “I believe that if all these conditions are met, we will be able to end the pandemic much sooner. I’d like to say by the end of this year, but I’m not even counting on that,” he admits. “There is a chance that we will be able to control the disease next year – if we are very lucky.”