but This coronavirus with us for long, say epidemiologists from different countries. We expect the annual wave of infection covid-19 and quarantines until 2025, scientists believe calling to observe social distance. However, an effective vaccine may improve the prognosis. Here’s what scientists predict for the next months and years.
June 2021. The world lives in the mode of a pandemic and a half years. The virus continues to spread slowly; periodic quarantines have become the new norm. Approved the vaccine gives immunity for six months, however, international transactions have slowed its spread. According to statistics, 250 million people worldwide were infected, 1.75 million dead.
Such scenarios assume, as a pandemic coronavirus will develop in the future. Worldwide, epidemiologists build short-term and long-term forecasts, to prepare and to mitigate the spread and impact of the virus, triggering covid-19. Although their predictions and time frames are different, scientists agree on two points: covid-19 here to stay, and the future depends on many unknowns, including the possibility of forming long-term immunity in humans, the influence of seasons on the spread of the virus and, perhaps most importantly, decisions of States and individuals. “Where the quarantine is removed, somewhere in there. We don’t know for sure what will happen,” says Rosand of Eggo, the developer models the spread of infectious diseases London school of hygiene and tropical medicine.
“the Future will largely depend on how to resume social mix, and what measures of prevention we take,” reports Joseph Wu, the developer of the models of diseases of University of Hong Kong. Recent models and evidence of positive impact of quarantines show that changes in behavior can reduce the spread of the coronavirus, if many, not necessarily all, will be to observe them.
Last week the number of confirmed cases covid-19 worldwide reached 15 million people, was 650 thousand deaths. In many countries weakened restrictive measures, and many people think that the pandemic is over, said Yonatan Grad, an epidemiologist at the Harvard school of public health. T. H. Chan in Boston, Massachusetts. “But it is not. We have a long way”.
If immunity to the virus lasts less than a year, for example, as is the case with other human coronaviruses, then we expect the annual wave of infection covid-19 until 2025 and later. In this article, Nature is the opinion of scientists about how events will unfold in the coming months and years.
of What will happen in the near future?
Pan��emia different flows in different territories. Countries such as China, New Zealand and Rwanda have achieved low levels of disease through quarantines of varying length and now lift the restrictions, but we monitor outbreaks. In other places, for example, in the United States and Brazil, the incidence increased rapidly after the government abruptly withdrew the restrictive measures or not introduced at all.
The second group of countries makes the creators of models to worry. For South Africa, which now ranks fifth in the world in the number of cases, a consortium of modellers estimated that the country can expect a peak incidence in August or September, when nearly one million cases, and by early November the country will have a total of 13 million people with the symptoms of the disease. As to hospitals, Juliet Pulliam, Director of the South African centre for epidemiological modelling and analysis Stellenbosch University, says the following: “In some regions we have already passed the feature level, so I think our best scenario is not optimistic”.
However, with the simplification of the restrictive measures came the good news. Early evidence shows that people’s behavior in regard to hand washing and wearing masks, is maintained even after the lifting of the quarantine. This helps to slow down the wave incidence. A June report team Center for global analysis of infectious diseases Imperial College London shows that in 53 countries, started with the lifting of restrictions, the rise in incidence did not exceed the threshold predicted on the basis of previous data. “Underestimated how much has changed people’s behaviour in relation to wearing masks, hand washing and social distancing. It’s not like before,” says Samir Bhatt, an epidemiologist specializing in infectious diseases, Imperial College London and co-author of the study.
Researchers in the “hot spots” of the spread of the virus, learn how useful new behaviors. At the University ANHEMBI Morumbi in Sao Paulo, Brazil, a computational biologist Osmar Pinto Neto and his colleagues have created more than 250 thousand of mathematical models of various strategies of social distancing, described as constant, periodic, and “falling” (when the restrictions are removed gradually). Along with them we studied the behavioral changes such as wearing masks and washing hands.
The team came to the conclusion that if 50-65% of the population comply with these measures, the simplification measures of social distancing every 80 days will allow you to avoid peaks in incidence in the next two years. “We’ll have to change our culture of communication with other people,” says No. Overall, this is good news. Even without testing and ��Accini of behavior change can significantly reduce the spread of the disease, he adds.
The developer models the spread of infectious diseases, Jorge Velasco-Hernandez from the National Autonomous University of Mexico in Horikita and his colleagues also studied the balance between quarantine and protection. They found that if 70% of the population of Mexico will wear masks and wash hands, and to comply with the withdrawal, which began at the end of March, then the incidence will decline after passing its peak in late may/early June. However, the government lifted the restrictive measures on June 1, and, instead of falling, the largest number of deaths from covid-19 per week remained unchanged. Team Velasco-Hernandez believes that a two state output was the reason for the rapid spread of the virus, causing high morbidity before the lifting of restrictions.
Regions where the incidence of covid-19 decreases, the researchers recommend closely monitor the situation through testing, to isolate new cases and trace their contacts. By the way, this is the situation of Hong Kong. “We experiment, observe and adapt slowly,” Wu said. He hoped that this strategy will prevent a massive surge in the incidence, but an increase in the frequency of air travel is threatened by the emergence of a large number of imported cases.
the However, as far as contact tracing and insulation really helps to contain the outbreak?
Analysis of groups learning covid-19, Centre of mathematical modelling of infectious diseases London school of hygiene and tropical medicine examined the new outbreak of contagiousness different from 5, 20 or 40 new cases. The team concluded that contact tracing must be fast and thorough. To control the outbreak, it is necessary to monitor 80% of the contacts of the sick for a few days. The group now evaluates the effectiveness of digital tracking contacts, as well as how much time she can spend in quarantine, said the co-author of the studies of Eggo. “It is very important to find a balance between how much time people can survive in isolation and how much is needed to contain the outbreak”.
Track 80% of the contacts is almost impossible in regions that still have thousands of new cases every week. Moreover, the highest estimated incidence is probably underestimated. The team from Massachusetts Institute of technology (MIT) in Cambridge in July published a study where the analysis of test COVID-19 in 84 countries. It shows that the real incidence around the world was 12 times higher than reported in official sources, CME��the chance was lowered by 50%. “Cases of the disease more than the official data tells us. As a consequence, the probability of getting sick is higher than people think,” says John Sterman, a research associate and Director of MIT system dynamics Group.
At present, mitigation measures of morbidity such as social distancing, should be preserved as long as possible, to prevent a second massive wave, says Bhatt. “It’s going to be the beginning of winter, when everything will be a bit more dangerous”.
of What happens when the cold comes?
It is already clear that the summer is unable to completely stop the virus, but the warm weather helped to keep it in regions with a temperate climate. In regions where the second half of the year colder, experts predict the acceleration of the spread of the disease.
Many respiratory viruses human influenza and other human coronaviruses respiratory syncytial virus — is subject to seasonal fluctuations, leading to a winter flare. There is a high probability that SARS-CoV-2 will follow the same logic. “I think that the prevalence of SARS-CoV-2 and a potential outbreak of disease will increase in the winter,” says Akiko Iwasaki, a Yale Immunobiology school of medicine in new haven, Connecticut. Available evidence suggests that the dry winter air improves the stability and spreading of respiratory viruses, and immune defense of the respiratory tract may be weakened by admission of dry air.
In addition, in cold weather people usually stay in areas where there is a risk of transmitting viruses through airborne droplets, explains Richard NEER computational biologist at the University of Basel in Switzerland. Models created by his team, show that seasonal fluctuations are likely to affect the spread of the virus and make it a containment in the Northern hemisphere difficult.
In future outbreaks of SARS-CoV-2 can occur every winter. The risk to the adult population, already ill from the disease, will fall, but everything will depend on how quickly disappears immunity to coronavirus, says Near. Moreover, the combination of SARS-CoV-2 and flu in autumn and winter can cause problems, says Velasco-Hernandez, who is conducting a study of how these viruses may interact.
It remains unknown whether the infection of another human coronavirus to protect themselves from SARS-CoV-2. In an experiment with cell cultures of SARS-CoV-2 and close to it SARS-CoV antibodies produced against a coronavirus, was in contact with others, but not neutralized and destroyed it.
To defeat the pandemic of the virus or will be eliminated throughout the world, but it is almost impossible, as it is too widely spread, or people will develop immunity to it, Perabo��EV or creating a vaccine. It is estimated that depending on the country 55-80% of the population should have developed immunity to it happened.
Unfortunately, existing studies show that we still have a long way to go. The analysis tests for antibodies, which show have You been exposed to the coronavirus and whether antibodies to it, said that only a small part of the population was infected. Model the spread of the disease to confirm this. A study of 11 European countries showed that, by 4 may the infection rate was 3-4%. These figures are derived from the ratio of the number of cases of mortality and number of deaths. In the United States, where more than 150 thousand deaths from covid-19, study of thousands of serum samples, conducted by the Center for control and prevention of diseases of the USA showed the presence of antibodies in 1-6.9% of the population, depending on the region.
of What happens in 2021 and later?
The course of the pandemic in the next year largely depends on the appearance of the vaccine and how long is the duration of immunity after vaccination or recovery from the disease. A vaccine form the immune system for decades, such as vaccines against measles or polio. Others will eventually lose its effect as a vaccine against whooping cough or flu. In the same way to some viral infections the immune system is produced in the long term, and the other — no. “The overall prevalence of SARS-CoV-2 by 2025, largely depends on the duration of immunity,” write Grad, Harvard epidemiologist Marc Lipsitch and their colleagues in the may document on possible scenarios.
the Testing for antibodies to coronavirus
While scientists know little about how long the immunity to SARS-CoV-2. One study recover from them shows that the antibodies persisted for 40 days after the onset of the disease. In some other studies stated that the level of antibodies decreases over weeks or months. If covid-19 follows the logic of SARS, there is a high level of antibodies must be maintained for 5 months and slowly decline over 2-3 years.
However, the formation of antibodies is not the only way of the immune defense. Memory b and T cells also protect us from future encounters with the same virus, but so far little is known about their role in the infection of SARS-CoV-2. For the exact answer to the question about duration of immunity, scientists need to explore a large number of people for a considerable span of time, explained Michael Osterholm, Director of the Center for research and policy in infectious diseases at the University of Minnesota, Minneapolis. “We’ll just have to wait.” If the incidence will continue to grow rapidly in the absence of vaccines and short-term immunity, “we will see regular intense movement of the virus,” says Grad. In this case��e virus will become endemic, said Pulliam. “It will be really painful”. And it’s not unimaginable. Malaria, a preventable and treatable disease that kills 400,000 people annually. “These scenarios are worst-case scenario unfolding in many countries, preventable diseases, causing high mortality,” explains Bhatt.
If the virus creates short-term immunity, as do the other two human coronavirus OC43 and HKU1, the immunity which lasts approximately 40 weeks, then people can get sick again, and every year we are waiting for new outbreaks, suggests the Harvard team. Supplementary report of the Center for research and policy in the field of infectious diseases, which provides research trends eight global pandemics of influenza, indicates significant activity covid-19 in the next year or two. It can be expressed in a series of decreasing peaks and valleys in a constant or slow the spread of the virus without any specific waves. However, these scenarios are just speculation, as to date the pandemic does not follow the scheme of a pandemic flu, explains Osterholm. “We are faced with unprecedented coronavirus pandemic”.
There is a chance that immunity to SARS-CoV-2 DC. In this case, even without the vaccine virus itself will disappear by 2021 after a global outbreak. However, if the immune system is moderate and lasts about two years, according to the Harvard team, it may seem that the virus is gone, but he’ll be back no later than 2024.
This prediction, however, ignores the invention of an effective vaccine. It is unlikely that a vaccine will never be invented. Its design has directed a huge amount of effort and money, in addition, some options are already being tested on humans, said Velasco-Hernandez. According to the who are now being tested on humans 26 variants of the vaccine, 12 of which are in the second phase, and 6 in the third. Even if the vaccine won’t provide complete protection, it will help to reduce the severity of the disease and avoid hospitalization, Wu explained. However, the production and distribution of a successful vaccine will take a few months.
The world will not be defeated covid-19 in the same way. Regions with a large number of old population will have a disproportionately more cases of the disease in the later stages of the epidemic, says Eggo. A mathematical model of her team, published in June and based on data from 6 countries, shows that the vulnerability to infection of children and people under the age of 20 almost two times lower than in more adults.
There is one thing that unites countries, cities and communities affected by the pandemic. “We still don’t know much about this virus,” says Eggo, — “until ��AK we will have more accurate information, we will all be subject to uncertainty”.
