In some countries, the pandemic is in full swing, but somewhere it has declined, and now many are wondering how and when it will end. The author examines how past pandemics have progressed and, based on this experience, makes a prediction about the future of Covid-19.
We know how the COVID-19 pandemic began: bats in the vicinity of Wuhan, China, have a mixture of coronavirus strains, and sometime last fall, one of the strains took the chance and crossed interspecies boundaries. He left his master (or masters) and moved into the human body. After that, the virus went all out.
However, no one knows how this pandemic will end. We have not yet encountered such a coronavirus. It is unprecedented because it is easily transmitted; he has many symptoms, from the most subtle and innocuous to the deadly; and he disorganized the whole world. The population turned out to be very vulnerable, and the incidence began to grow exponentially. “This is a special and completely new situation,” says Sarah Cobey, an epidemiologist and evolutionary biologist at the University of Chicago.
But past pandemics give us clues about what to expect in the future. There is no example in history that we could follow, but humanity has experienced several major epidemics over the past 100 years, which eventually ended and stopped destroying society. How they ended could be a guide to action for today's world, which is looking for ways to restore public health and return to normalcy. According to Kobe and other experts, there are three important points that indicate the following: what happens next depends on the evolution of the pathogen and how the person will react to it biologically and socially.
Problem spread
Viruses mutate constantly. Those that cause a pandemic are quite new and unusual, and therefore the human immune system does not immediately recognize them as dangerous invaders. They force the body to create entirely new defenses involving new antibodies and other components of the immune system that are able to react to and attack the enemy. Large numbers of people get sick in a short time, and social factors such as crowds and lack of medication can further increase the incidence. Ultimately, in most cases, antibodies produced by the immune system to fight the invader appear in large numbers of people, and they acquire long-term immunity, and transmission of the virus from person to person becomes limited. But this may take several years, and before that, chaos will reign.
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The most famous example of this development in modern history is the Spanish H1N1 flu epidemic in 1918-1919. Doctors and health workers had far fewer remedies at the time than they do today, and the effectiveness of administrative measures such as school closures depended on how timely and decisive they were. In two years, the pandemic, which came in three waves, infected 500 million people, and between 50 and 100 million died. It ended naturally when those who had been ill and recovered received immunity.
The H1N1 strain has become an endemic infectious disease that is constantly present among us, affecting humanity with less brutality. For 40 years this strain has circulated as a seasonal virus. In 1957, another pandemic occurred, this time involving H2N2, which largely eradicated the 1918 strain. In fact, one flu virus eliminated another, and scientists don't know how it happened. When a person tried to do this, he did not succeed. “Nature can do it, but we can’t,” says Florian Krammer, a virologist at the Mount Sinai School of Medicine in New York.
Containment
The SARS (SARS Severe Acute Respiratory Syndrome) epidemic of 2003 was not caused by the influenza virus, but by the SARS-CoV coronavirus, which is a close relative of the culprit of the current SARS-CoV-2 coronavirus pandemic. Of the seven known human coronaviruses, four are widespread and cause up to a third of acute respiratory viral infections with ARVI. The one that caused the SARS outbreak was much more dangerous. Thanks to proactive epidemiological actions, such as isolating cases, quarantining those in contact with them, and social control measures, acute outbreaks have been limited to a few foci such as Hong Kong and Toronto. Such containment became possible due to the fact that the disease occurred immediately after infection - very quickly and clearly. Almost everyone infected with the virus developed serious symptoms:fever and shortness of breath. And they passed the virus after they got sick, not before. “Most people with SARS became infectious about a week after symptoms appeared,” says epidemiologist Benjamin Cowling of the University of Hong Kong. "If they were identified during this week and isolated, establishing good infection control, then they no longer spread the disease." The containment measures were so effective that there were only 8,098 SARS cases worldwide and 774 deaths. Since 2004, the world has never seen a single case of SARS.says epidemiologist Benjamin Cowling of the University of Hong Kong. "If they were identified during this week and isolated, establishing good infection control, then they no longer spread the disease." The containment measures were so effective that there were only 8,098 SARS cases worldwide and 774 deaths. Since 2004, the world has never seen a single case of SARS.says epidemiologist Benjamin Cowling of the University of Hong Kong. "If they were identified during this week and isolated, establishing good infection control, then they no longer spread the disease." The containment measures were so effective that there were only 8,098 SARS cases worldwide and 774 deaths. Since 2004, the world has never seen a single case of SARS.
Vaccine
When a new influenza H1N1 virus, known as swine flu, caused a pandemic in 2009, alarm was raised because it was a completely new H1N1 virus, very similar to the 1918 killer virus, Cowling says. But the swine flu was not as bad as scientists thought. “In part,” says Krammer, “we were lucky because the pathogenicity of the virus was not very high.” But there was another very important reason: six months after the appearance of this virus, scientists created a vaccine to combat it.
Unlike measles and smallpox vaccines, which provide long-term immunity, influenza vaccines provide protection for only a few years. The flu virus is very insidious and mutates quickly to bypass the immune system. As a result, the vaccine has to be improved every year and people have to be vaccinated regularly. But during a pandemic, even a short-acting vaccine can be a boon. A vaccine created in 2009 helped contain the second wave of the epidemic in the winter. As a result, the swine flu virus followed the lead of the 1918 virus much more quickly, becoming the common seasonal flu, from which many today are protected either by vaccinations or by antibodies from previous infections.
The final phase of the current pandemic
Predictions about what will happen to COVID-19 are speculative, but at the final stage, a set of measures can be applied that have more than once stopped previous pandemics. These include maintaining public oversight to buy time, new antiviral drugs to ease symptoms, and a vaccine. The exact formula for, say, how long to maintain social distancing rules depends largely on the people themselves, on how accurately they follow restrictive measures, and how effectively the authorities will respond. For example, the containment measures that were used to stop COVID-19 in Hong Kong and South Korea, in Europe and the United States, were taken too late. “The question of how the pandemic will develop is at least 50% dependent on social and political factors,” says Kobe.
And the remaining 50% should be provided by science. Scientists have rallied like never before and are working on many fronts to find a cure. If any of the antiviral agents currently being developed prove to be effective, they will improve the treatment method, and the number of severe cases and deaths will decrease. Searching for antibodies that neutralize SARS-CoV-2 can also be very useful, since they are an indicator of immunity in recovered patients. Krammer and his colleagues developed one such search method. There are other methods as well. Previously, antibody serological testing was only used in localized epidemics, and new search methods will not end the pandemic. But they will allow the identification and use of blood with high levels of antibodies to treat critically ill patients. And these tests will also allow people to return to work faster if it will be possible to identify those who have recovered and have received immunity.
A vaccine is needed to stop the spread of the disease. It will take time, most likely a year. But there is reason to believe that the created vaccine will be effective. Unlike the flu virus, the coronavirus has fewer ways to interact with the host's cells. “If this communication stops, the virus will no longer be able to replicate,” says Krammer. "And this is our advantage." It is unclear whether the vaccine will provide long-term immunity, as with measles, or short-term immunity, as with flu shots. “But at the moment any vaccine will be beneficial,” says epidemiologist Aubree Gordon of the University of Michigan.
If all eight billion inhabitants of our planet who are not sick or have recovered are not vaccinated, then COVID-19 may become endemic. The disease will become seasonal and will affect people from time to time, and sometimes very seriously. But if the virus stays with us long enough, it will start infecting young children. Usually, their illness is fairly easy, but not always, and while adults who have been ill in childhood, the recurrent illness is not very difficult. The combination of the vaccine and natural immunity will protect many of us. The coronavirus, like most viruses, will continue to live, but it will no longer become a disaster on a planetary scale.
Lydia Denworth