The BBC reported on Thursday that a patient who had tested positive for COVID-19 for a record 505 days had died. On Thursday, NBC News reported that a woman in Spain had contracted the omicron variant of COVID-19 only 20 days after contracting the delta variant.
These are out-of-the-ordinary circumstances. The patient with the extremely long COVID-19 case was suffering from serious medical conditions that suppressed their immune system. The woman who had two cases in less than three weeks was a health care worker who was at high risk of exposure due to her job. But there is something to be drawn from both of these cases—something that was true a year ago and continues to be true today.
Every person infected creates approximately 10,000,000,000 new instances of the SARS-CoV-2 virus. Every single one of them is susceptible to mutation. Those mutations are then sifted through by the one evolutionary pressure that viruses face: increasing their R0 number.
When it comes to humans, COVID-19 is a brand new disease. Nobody, and I mean nobody, has a natural immunity. There is no nearby but mild infection (like cow pox) that could provide some protection. COVID-19's newness makes it nearly infinitely more dangerous than diseases we've been dealing with for centuries.
COVID-19 is still undergoing unguided mutation in order to find the best way to infect human cells. The huge gains made in each generation of variants demonstrate the newness of that process. Alpha was twice as contagious as the original variant that ravaged Europe and the United States, and Delta is more than twice as contagious as Alpha. That kind of change does not occur in well-established, long-term disease.
That was written prior to the appearance of the omicron variant. According to the most recent estimates, omicron BA.1 is 3.19 times more infectious than delta. The BA.2 subvariant of Omicron is approximately 30% more infectious than the BA.1 subvariant. This puts COVID-19's basic reproductive number (R0) at around 16 to 18, putting it on par with pertussis and measles, the most infectious viruses in circulation. COVID-19 had a R0 value of between 2.0 and 2.5 when it first appeared in China before spreading to other countries. The rapid increase in that number indicates that this is a virus with a high potential for explosive growth. It's still learning how to avoid the immune system, which includes overcoming the effects of both vaccines and previous infection.
This is still a relatively new virus with a nascent relationship with Homo sapiens. And it's never been more critical to limit the number of infections, limit the SARS-CoV-2 virus's ability to generate trillions of new attempts to breach barriers, and avoid allowing everything that's happened so far to be just a prelude.
Before proceeding, it is important to note that SARS-CoV-2 is neither malicious nor conscious. It is unable to make plans. It has no "desire" for anything. It is a quasi-living particle that can reproduce and undergoes changes as a result of a combination of random chance and selective pressure. That is true to a large extent for all living things, but nowhere is it more true than with viruses.
Researchers from the University of Valencia stated in a 2013 paper, "RNA viruses are among the fastest mutating and evolving entities in nature." The SARS-CoV-2 virus is an RNA virus. It changes faster than a DNA virus, such as the variola virus that causes smallpox. And, because the time between human contact with SARS-CoV-2 is so short, those changes can have a significant impact.
Here's a quick look at one indicator of how quickly SARS-CoV-2 is evolving.
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