[00:00] When is the COVID pandemic going to end? So many people have been comparing the Spanish flu to SARS-CoV-2. For example, the Spanish flu took place over two years, between 1918 to 1920,
[00:13] and consisted of four waves. So here we are, almost two years later, and there have been four waves. So it'll end in 2022, right? Right? Today we're going to break down how this all might end, with specific predictions based on expert opinions,
[00:27] past virus trajectories and up-to-date research and models. Let's go! First off, a reminder that this novel coronavirus carries its genetic info as RNA, not DNA, and is considered an intracellular parasite, which is a fancy way of saying it can only
[00:44] reproduce within cells. So SARS-CoV-2 may think she's that girl, but it's like, are you even alive? Call me when you have your own cells or a metabolism, hun. Although maybe we shouldn't be making fun of her, because currently she's doing a great job infecting us all. Even though the flu is also an RNA virus, it is different than the
[01:00] current RNA coronavirus that we are all talking about. So to understand what is going to happen to us in the future, it's also worth looking at the coronaviruses or colds that infect all of us each year. A new genius study went back to look at blood samples over multiple decades for the
[01:14] seasonal coronavirus 229C because this virus is able to infect people repeatedly throughout their lives. But what they realized through the blood samples was that individuals in the 80s had different immune markers than those in the 90s and even more so from those in the 2000s. This
[01:30] makes researchers think coronavirus 2 to 90 might also be mutating throughout these decades. That's maybe what's causing reinfection. It's not just fading immune response. So the big question is, when will SARS-CoV-2 virus join the other four coronaviruses that circulate throughout populations
[01:46] infections and cause relatively mild colds. How does that happen? Now that is the big question. On the one hand, it could become endemic, meaning infections stabilize without these unexpected spikes. That would require a low reproduction number, like R1, meaning
[02:01] an infected person is likely to infect only one other person. Not like this Omicron variant, which is making graphs of COVID cases look like a comedic joke straight wound up. On the other hand, SARS-CoV-2 could become something more threatening like a bad flu or some sort
[02:16] even worse? It's a myth to say that viruses only evolve to become more mild, which is a narrative that keeps getting pushed. It possible but the reality is far more complex The RNA inside is a blueprint that needs to get its genetic material into the cytoplasm of your cells then the ribosome starts reading the blueprint three nucleic acids at a time and then strings them together and creates the protein But occasionally the wrong nucleic acid will get added to the
[02:42] chain. This can sometimes lead to changes, making an offspring virus different from its parent. And these random changes can sometimes be advantageous to the virus. Early genome sequencing of the SARS-CoV-2 virus showed that it was picking up around two single-letter
[02:56] mutations for months. There are two important ways to think about how mutations affect the virus that we are currently all fleeing from. One is its transmissibility, like mutations that make it replicate faster or make it more contagious to others. And two is its ability to evade immune
[03:13] response, like mutations in the spike protein that make it sneak past our immune system. Gamma and beta have a slew of mutations in the same thing spike protein we're all talking about that may it signed more easily to ACE2 receptors in your body,
[03:27] and that made it more easily absorbed into your cells, meaning, boom, it's more transmissible. It's more likely to gain these effective mutations the longer it replicates in a host. So the longer you are sick, the more likely these mutations can happen.
[03:40] This is why these mutations are more likely to happen in people who are not vaccinated or in people who are immunocompromised. King Delta, identified in spring 2021, was 60% more transmissible than any other strain before
[03:52] because of mutations that researchers think caused it to replicate faster in the airways of infected individuals, outpacing the initial immune response, especially, again, in those unvaccinated. So, boom, you have increased transmissibility and evading immune response.
[04:08] Delta is more transmissible than the current flus we deal with, or any of those four common colds that we talked about earlier, but it's less transmissible than measles and polio. It's also nice to know that this transmissibility of a virus can't just increase forever.
[04:20] We're dealing with the laws of nature here, and there are certain parameters on our biology. The virus needs to toy with the ability to replicate in thine airwaves and lungs, but also with making sure we're not so sick it wants us to be out there and spreading.
[04:35] It doesn't want us to be sick at home in bed, not able to move. The virus wants to infect my family. And when we say want here, a gentle reminder that the virus isn't sentient and doesn't consciously want these things. It's just that the more optimal versions of the virus will spread more effectively
[04:51] out-competing other variants that might be too deadly or not transmissible enough. Omicron came out of left field like she stomped on the team. This baby has 30 mutations in the spike protein and has evolved to infect people who are immune through vaccination or previous infection to Delta But as daily and transmissibility slow it needs to figure out ways to continue to overcome immune responses
[05:13] which is probably what's happening right now. Experiments and lab sequencing of variants circulating right now have identified a bunch of mutations in spike proteins that weaken your body's immune response, which have been boosted by vaccination or prior infection.
[05:26] But the important thing that we do know is that vaccines continue to protect against severe disease. Your T-cell-mediated immunity created by the mRNA vaccine is a huge step in speeding up and overcoming this pandemic.
[05:39] And that's why getting the world vaccinated is so important. That doesn't mean it'll just go away overnight, but being vaccinated continues to make you more resilient to any mutations in SARS-CoV-2 over time,
[05:51] as it's proven to make you less sick. Perhaps even more important is that it allows you to not contribute to the problem of it becoming even more transmissible or evading immunity. So continued vaccination can build up a wall of immunity that the virus can no longer overcome.
[06:05] Essentially, if the whole world was suddenly vaccinated at once, the overall T-cell-mediated immunity would be high enough to help us be more resilient to any upcoming changes of the virus, and as a result, it wouldn't be able to spread as fast and likely become endemic more easily.
[06:19] As of now, there are six scenarios that experts think about our future for COVID. One, we do a better job vaccinating the world. The overall T-cell immunity of humanity increases, making the virus more likely to be endemic,
[06:33] resulting in outbreaks and epidemics of varying sizes like other respiratory infections you already have, more like the current coronaviruses and flu we all deal with. Two, still considered endemic, we have small changes in the spike protein that open up parts of society to reinfection.
[06:48] The virus continues to evolve, but we combat waning immune responses with annual vaccines, like the flu shot. And the only people who are highly susceptible are those who are unvaccinated and children born without immunity.
[07:00] Three, just unscared but not likely, we invent a vaccine, like the measles vaccine, that offers lifetime protection. And the only people who are susceptible are newborn kids. Four, it ends up like respiratory syncytial virus, meaning it's around, like, maybe forever.
[07:16] But in the far future, most people get infected in the first two years of life. It is mild for most kids, but it does cause high hospitalization rates overall for infants. As it spreads or evolves, adults have mild symptoms due to their exposure they already
[07:31] had as a kid. 5 It ends up like influenza A the little bugger that drives global flu each year This bee has rapid evolution and spreads with new variants that are able to escape the immunity elicited
[07:43] by past strains. This results in seasonal epidemics, largely spread by adults who can still have severe illness. Like the flu vaccine, our annual coronavirus vaccine will decrease transmissibility and decrease severe disease. But the quick mutation means that these vaccines
[07:59] aren't always properly designed for the specific strains of the year and will need to continually be updated. Sixth, it ends up like influenza B evolves more slowly and is driven largely by infection in children who have less immunity than adults
[08:13] who are more immune from prior infection and vaccines. It's important to remember that how quickly SARS-CoV-2 evolves in relation to immune response will continually explain how often you need to be updating these vaccines.
[08:26] Right now, this coronavirus is evolving faster than other seasonal coronaviruses or influenza A, but experts do predict that it'll slow down to maybe needing an updated vaccine every year, like the flu, or potentially every two or five years.
[08:39] But it's equally possible that it could mutate into something worse. We just can't know for sure. A lot of people are looking at the UK and the US strategy right now, which is just to sort of let the virus rip and potentially infect almost everyone.
[08:51] And while this might be a high-risk, high-reward strategy, it's also leaving really fertile ground for SARS-CoV-2 to take surprising evolutionary leaps. Only time will tell if that'll breed new strains that can reinfect people at high rates
[09:05] or more effectively evade vaccine immunity. So, what did I miss here? Hey, I guess it kind of depends on what the word end means to you. We may be hearing about this for years to come, even though it's not infecting people as severely as it is right now.
[09:20] Regardless, the future is in our hands in some ways. it is important that we vaccinate the whole world, not just the wealthy nations. Because as homo sapiens sapiens suffering from this disease, it is important that we all have the increased T-cell-mediated immune responses
[09:36] to help fight against this virus's ability to change or mutate and therefore cause the next wave in the coming future. We hope this video helped. What's happening right now seems complicated, but it's not as deep as lots of people are trying to make it seem
[09:50] with conspiracy theories and all these things. It's just about biology, virology, and evolution, and how all of these things are going to play out with the amazing science that we currently have. Thank you for watching. Share this with any friends who might need to hear it.
[10:03] I know this research has helped me sort of understand what's going on. And we'll see you next week for a new science video. Also, peace!