it is difficult to predict how the covid-19 pandemic will develop further. based on experience with other infections, there is no reason to believe that sars-cov-2 will disappear any time soon, even if vaccines are available. a more realistic scenario is that covid-19 will be added to a large and growing family of infectious diseases known as 'endemic'.
what does this mean? and what will a coronavirus pandemic look like if it makes this list?
what are endemic diseases?
before talking about coronavirus and making predictions for the future, you first need to find out what endemic diseases are. what is their nature? why were they named that? and what made scientists put them on the same list?
in epidemiology, an infection is considered endemic when a certain level of incidence is maintained in a geographic area without external intervention.
for example, chickenpox or chickenpox is endemic in the uk, but malaria is not. several cases of malaria are reported annually in the uk, but they are not epidemic due to the lack of a suitable vector. we remind that the mosquitoes from the genus anopheles are the vectors of malaria plasmodia.
in theory, an infection becomes endemic if, on average, every infected person transmits it to another person. in other words, when the base reproductive number (r0) is 1. the base reproductive number (r0) shows us the average number of healthy people infected by one carrier of the infection. for example, if r0 is 2, it means that each infected person will infect two other people.
in case of endemic diseases, the base reproductive number (r0) should be equal to one. during an epidemic, the spread of the disease increases, r0 is greater than 1, and when the spread is reduced by control measures or immunity, r0 is less than 1.
will covid-19 become endemic?
with the incidence of coronavirus on the rise again globally, it is clear that current measures can only contain the spread of the disease. the only exception were countries that can really isolate themselves from the outside world. the fact that the vast majority of people are still susceptible to disease means that there is enough fuel to keep the fire going for some time.
this will be the case even if certain countries achieve so-called herd immunity, but it is not yet clear how realistic this is. when a sufficient number of people become immune to coronavirus as a result of vaccination or natural infection, the spread of coronavirus infection will begin to slow down, and the number of infected people will gradually decrease. but this does not mean that the disease will disappear instantly or completely. no measure of isolation is strong enough to completely stop human interactions between regions, within and between countries, or around the world.
it is likely that the spread of the infection will eventually stabilize at a certain level, so that it will be constantly present in the communities, but perhaps at a relatively low and sometimes predictable rate. this is what we mean when we say that a disease has become an "endemic disease."
access to a vaccine doesn't mean the disease will go away!
as long as there are enough people still susceptible to coronavirus infection for every infected person to transmit it, it will continue to spread. in diseases that only provide temporary immunity as a result of natural infection, people lose their immune defenses and become susceptible to infection again. a virus or bacteria can also evade immune memory through mutations, so that people who are immune to the older strain become susceptible to the new version of the disease. the flu is a good example.
we still don't know how long immunity against coronavirus infection will last or how well vaccines will protect people. but other coronaviruses that are endemic to the human population, such as the common cold, provide temporary immunity for about a year. another important point is that people with immunity from infection or vaccination are rarely evenly distributed in their community or country, let alone the world.
of course, in the case of covid-19 there are areas where the infection has spread more intensively, while in others everything is relatively calm. but without evenly spreading disease, herd immunity will not develop even if doctors vaccinate enough people to reach the predicted threshold. in this case, the average baseline reproductive number may be low enough to bring the infection under control, but in unprotected outbreaks it will be much higher than 1. this will lead to localized outbreaks and allow the disease to remain endemic.
how do we deal with covid-19?
how we coexist with coronavirus once it becomes endemic will depend on how good the vaccines are and whether slightly more precise treatments are established. if therapies and vaccines can help avoid more serious consequences, then covid-19 will become like many other diseases with which we have learned to live.
depending on whether the immunity is permanent or temporary, whether it is natural infection or vaccination, there is a possibility that we may need an annual vaccination, such as in the case of the flu vaccine. or to contain coronavirus infection will be obtained by vaccination at an age that is considered optimal for preventive purposes (as in many childhood infectious diseases).
if vaccines not only protect against disease, but also significantly reduce the spread of the virus and provide long-term immunity, then we can imagine other scenarios, including the possible eradication of the disease. but unfortunately this is unlikely. it is known that it is difficult to completely eradicate a disease even in the case of diseases for which we have almost perfect vaccines and permanent immunity. therefore, an endemic disease is the most likely outcome.
some endemic diseases that are widespread in the world
some infections are present and actively spread almost everywhere. for example, many sexually transmitted infections and childhood infections. here are some examples:
malaria is an endemic disease that is widespread in africa, asia, latin america and the middle east. the causative agent of malaria is plasmodium - parasitic protozoa of the plasmodium genus, which destroy red blood cells in the human spleen and liver, which leads to anemia and death if treatment is not started on time. annually in the world from 200 to 500 million people suffer from malaria, of which about 1.5-2.7 million die.
chickenpox or chickenpox is a viral infectious disease that manifests itself as an itchy blistering rash. chickenpox is highly contagious to people who have not had it before or have not been vaccinated against it. today there is a vaccine that protects children from chickenpox. chickenpox is especially contagious in winter and early spring.
3.coronaviruses and arvis
there are many types of coronavirus that can cause colds and pneumonia. although the human coronaviruses 229e, nl63, oc43, and hku1 are less well-known than some of their counterparts, they still cause respiratory illness around the world, especially in winter. they account for about 15-30% of colds.
4. hiv infection
there is no aids epidemic in the world, but sub-saharan africa remains the most affected region. hiv infection has become endemic in sub-saharan africa. and although only 12% of the world's population lives there, two thirds of them have hiv. the adult hiv prevalence rate is 5%, that is, between 21.6 and 24.1 million people suffer from the disease.
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