Viral exploitation | Source: pngtree.com The course of a Pandemic lasts for only a few years. Covid-19 is no exception. If the current data are close to accurate, it seems that the founding Sars-cov-2 strain that has begun to spread in the US, and in both South and East Asia is relatively around 2–10x weaker (excluding the hosts' genotypic and epigenetic factors) or less virulent than the founding strain that has been spreading in southern Europe. Any else, was it immunity through cross-reactivity from previous distinct coronavirus infections, including unknown types, that provided variations of disease severity between geographical locations? As of now, the reported mortality rate of <1% to 5.9% in southeast Asia is a far split from those of 4.6% to 18.9% in southern Europe. "Country-by-country data and research on the pandemic. Updated daily." Vaccines usually take many years to develop—not a few months, not in a year or two. International coordination and better technology are the factors that have been hastening the headway of Covid-19 vaccines though. In the case of the Dengue vaccine, even if it took several years of clinical trials, still there was a significant unintended consequence that had manifested or had been recognized too late. We should’ve known to have had followed a criteria. In fact, there’s threatening information about Sars-cov-2 of also having a characteristic of Antibody-Dependent Enhancement involved with a subset of receptors. What if a certain human population has a higher load of those antibody-associated receptors that are conjunctly non-neutralizing than the receptors that are preferably "protective"? For them, the vaccine can end up being either of the extremes: deadly or, hopefully, curative Antibody-Dependent Enhancement = 'Trojan horse' | Source: https://thenativeantigencompany.com/ How will this pandemic end if ever the vaccines are ineffective or hazardous? Or what if the vaccines fail to encompass all the present strains? "2 Billion Doses of Oxford's Unproven Coronavirus Vaccine Will Soon Be Ready to Produce" To have a grasp of the following topic, let’s first review these three terms: Infectivity - will this microbe/parasite/virus spread to another host upon exposure? Pathogenicity - will it cause disease when infected? Virulence - will the disease be severe or lethal? Could a Virus, such as Sars-cov-2, inherently mutate to a less lethal strain? How? The likelihood of having these mutations that can produce new genotypes is augmented or magnified collectively in a pandemic by the fact: for every additional individual infected, the chance is compounded for some viral particles, among thousands to trillions inside an infected host, to mutate and generate a new strain. Now, which among these strains have the tendency to reproduce with success? Since viruses are rapidly ever–mutating, every chance upon reproduction, the probability for them to build/maintain a trait with an attribute of increasing its virulence (i.e to acquire a new “skill” which has to have an exact set of expressible genes that translates to a product that is concordant to its host cell’s affinity along with a more potent ability to disarray and exploit the cells’ microenvironment or program) is very low as opposed to the probability of disrupting or disorganizing those old/new sets of highly virulent alleles; in as much as Natural selection still would allow their low-virulence progenies to proliferate due to an evolutionarily–maintained high infectivity. Only few specific mutations to precise orders in certain regions of a genome will enable a new allele to elicit a "gain of function". The descendants of low-infectivity phenotypes would be eradicated, retaining the infective but non-virulent ones. This course takes more than a year even in this sort of accelerated spread of infection. A specific and precise order in a viral gene is required to elicit a "gain of function" | Source: dreamstime.com Upon replication and recombinations, which of these mechanisms has a high propensity to come about whenever a mutation occurs? Maintain or repair a functional sequence of nucleotides/genes Disassemble (Fail to repair) a functional sequence of nucleotides/genes Assemble spontaneously a novel, specific, organized and functional sequence of nucleotides/genes In accordance to the interconnections of Biological systems with the Law of Entropy, diverse species or strains are to be continuously generated, although most are to become extinct. It is fair to say that all biological phenomena in their molecular aspects are also under the dynamics of a Stochastic process. Therefore, when it comes to viral mutations, the events of arriving at disorganized or non-sequenced nucleotides markedly outnumber the events of creating a new sequenced and functionally virulent allele. After all, it doesn't follow a binomial distribution alone. During mutations, the random rearrangements of their genomes would regard the processes of repair or disassembly as predominant. The low probability of assembling a new working sequence of genes that is virulent would allow the populations of infective, non-virulent types to prevail. Furthermore, evolution to a more virulent kind is actually surreptitiously burdened by a higher pathogenicity. How? The lineage of a highly pathogenic strain will be engrossed and will be actively exterminated not only by our immune system, but also by doctors, hospitals and medicine. This leaves us with the “infective” but non-pathogenic strains that remain to reproduce. How a Pandemic naturally ends Thus, all in all, Sars-cov-2 will likely get weaker over time then just become innocuous yet ubiquitous — much like commensalism between multiple bacteria/viruses and their host or human body — though not any time so soon. It probably won't happen within a few years for the strain in Europe, but perhaps sooner with the one in Asia. It would first convert to a lesser form, like the common cold. The transition to a less virulent strain is gradual. Genetic shift might be the only process, excluding artificial engineering, that could radically “reverse” a natural chronology like this. Nearly the same concepts can be hypothetically applied as to how bacterial pandemics in history ended. However, bacteria have a better nucleotide monitor or strand repair mechanism than viruses, so they don't mutate as quickly. What else differs? Instead of the same "viral genus/species” with variable virulence and pathogenicity striving in the natural selection, the populations of pandemic bacteria (e.g Yersinia pestis) have been overcome in their niches/hosts not only by different genus/species of fellow bacteria, but also by different family/order (e.g Family of Enterobacteriaceae or Order of Bacillales), since phyla to genera and species of bacteria outcompete with each other for resources to survive and reproduce. That’s why you won’t easily encounter a non-pathogenic Yersinia pestis anywhere. Nevertheless, you can find vast florae or populations of harmless microbes or viruses everywhere.
