This will be a sequel of sorts to my previous post, as there were a few bits of Covid information that I thought would be worth talking about but didn’t fit neatly into that entry’s theme of the new vaccines. To those who asked questions after my last post, I’ll try to address them here. There have been a lot of recent developments in the pandemic fight. I’ve done my best to provide the most up-to-date perspectives and information. However, it is a bit of a moving target at this point.
New Covid Strain
So you might have heard news of a new strain of Covid-19 out of England that is more contagious than regular Covid-19. This strain, officially named B.1.1.7, contains three unique mutations which are believed to improve the virus’ ability to enter a host cell.
Coronaviruses aren’t as prone to mutation as other viruses such as influenza, but every time a new copy of a virus is created inside of another human host, there are some odds that the new copy won’t be an exact replica of the old one. And with exponential proliferation and the creation of trillions of individual Covid-19 viruses this past year through the human population, the development of new strains is almost inevitable.
Research is being hurriedly done to better understand this strain and its properties. The new strain is approximated to have an R0 value roughly 0.4 higher than the original virus, meaning each patient with this strain will infect an average of 0.4 more people than those with the wild-type (original) strain. There is speculation that the new strain may be infecting children more than the original strain. While hard evidence for this hasn’t been found yet, the UK has seen an uptick in Covid cases in children. Though the new strain is more contagious, it does not appear to be any deadlier. That said, a more contagious strain is concerning because it could lead to more cases, which leads to greater hospitalization which could indirectly cause higher mortality if hospitals become overwhelmed.
Fortunately, all evidence supports that both Covid vaccines are just as effective against this new strain as original Covid-19. Despite these mutations, the two viruses are over 99% identical. Also, all of our existing measures to resist Covid, wearing masks, social distancing, etc., are just as effective against the new strain. A more infectious strain of this virus is certainly scary, but the solutions and workarounds are the same as they were.
Reinfection
A big concern with Covid-19 has been the risk that it might be possible to catch the virus multiple times. It’s commonly accepted knowledge that once you’ve caught a virus, you can’t catch it again, and that is true for the most part. But the truth is slightly more complicated. I’ve talked before about how the immune system works, but to recapitulate, the first time the body is infected with a particular pathogen, it develops a specific antibody which binds to said pathogen and disables it. The body continues to make these antibodies for the rest of its life, which is theoretically enough to prevent any future infection. In practice though, the body does not produce the same amount of antibodies forever. It would be a waste of resources to produce the maximum amount of antibodies for an infection one doesn’t have, so the immune system adjusts its antibody production to fit with its needs. This usually means constantly producing a small amount of antibodies, enough to slow down an initial infection, but upregulating production once an infection has started, enough to smother it before symptoms can occur. But this variable antibody response creates room for it to be somewhat ineffective at times.
I’ve spoken at length about how for a vaccine to be effective, the body must believe the “infection” introduced by the vaccine poses a legitimate threat. This is why it’s important to get both doses of either Covid vaccine and to get them within a month or so of each other. That’s what it takes to convince the body that this is a threat worthy of a strong, long-lasting antibody response. But the same thing can happen in naturally occurring infections too. It was concluded fairly early in this pandemic that those who had a milder case of Covid-19 had a weaker immune response to the virus, which meant they were less protected against a second infection than someone who had to be hospitalized. If one has milder symptoms, say because they received a smaller viral load, their immune system might conclude Covid-19 doesn’t pose a significant threat. And should they later be reinfected, possibly with a much larger viral load, their initial antibody response might not be enough to prevent symptoms from manifesting. On top of this, coronaviruses are notorious for not creating long-lasting immune responses. The exact reason for this is still unknown, but this was a concern for vaccine development since very early in the pandemic. Many of the viruses which cause the common cold are coronaviruses, and this is part of the reason why one can get the common cold multiple times.
The good news is that Covid-19 reinfection appears to be rare. It’s difficult to determine exact statistics during an ongoing pandemic, but there have only been a few hundred reported cases of Covid reinfection worldwide out of over 80 million confirmed cases. The majority of recorded Covid second cases can be better explained by one infection; symptoms manifest, fade away, and appear again. In order to prove it was two separate infections, episodes need to be more than one month apart and there needs to be a DNA test to confirm they were caused by two separate strains of Covid-19. There appear to be several factors which make reinfection more or less probable, and I’m certain that will be a topic of research for decades to come, but the odds are definitely in your favor.
This leads to the big question; how sure are we that the Covid vaccine will create long-lasting immunity if a real infection doesn’t always do so? Again, this was a concern from the beginning. Covid-19 is the first vaccine made for a coronavirus and many have said that a vaccine wasn’t a guarantee. But studies conducted since then seem to show there is a difference between those seasonal cold viruses and Covid-19; antibody responses to Covid-19 on average remain stronger for longer. Recent studies from the WHO show that even after eight months, 90% of subjects still have a robust immune response to Covid-19. That said, no one can say how much longer this immune response will last since the virus has only existed for about a year. And this is why this new technology is being used for these vaccines and why it’s important to get both doses within the recommended timespan. mRNA vaccines look a lot like a legitimate infection and getting two within a month tells the immune system that this is a long-term threat. How long the immunity created by these vaccines will last is the next big question and I’m certain it will continue to be monitored for a long time. It’s also important to get the vaccine even if you’ve already had the virus, because the immunity created by the vaccine will last longer. But even a vaccine that only lasts a few years would be a huge advantage, allowing the pandemic to fizzle out as herd immunity is reached and potentially being maintained with booster vaccines. Whatever happens next, it will be an improvement.
Why Two Doses Within Three Weeks
A question I’ve heard from a few different sources is ‘given how hard it is to manufacture and transport these vaccines and how many people need to be vaccinated, would it be a better use of resources to give everyone just one dose so everyone can get some immunity in only half the time?’ Given how logistically difficult it is to give everyone on Earth one vaccination, much less two, this is a somewhat understandable position. But this is...riskier than it sounds.
As stated above, a major problem with any vaccine for a coronavirus is how long that immunity will last. This is why all of these vaccines use two doses; one to create an immune response, the next to ensure that response lasts as long as possible. The concern is that if one were to only get the first vaccine and then wait longer than three weeks for the second, their immune response to Covid-19 would fade away completely before they received the second dose, effectively turning that second dose into another first dose, which would fade away over time as well.
Now in fairness, no one is quite sure how long one can go without the second dose before this immunity fades away. There is research to suggest that one could go up to eight weeks between doses and it would still be effective. That said, these vaccines were designed to be taken three weeks apart. The 95% effectiveness statistic was based on taking them three weeks apart. It took the better part of a year to conduct the research that confirmed ‘95% effectiveness at three weeks apart’, so it will likely take a similar amount of time to confirm the vaccine’s effectiveness with other schedules. That’s not to say the vaccine will definitely be ineffective unless both doses are taken three weeks apart, merely that administering the doses months apart would be using these vaccines as they weren’t intended. We know they work when used as they were intended, we’re far less certain of what happens when they aren’t used as intended.
President-elect Joe Biden recently announced his intention to release stockpiled vaccines to give as many people as possible their first dose, then accelerating vaccine production in order to get the second dose to people as quickly as possible. In theory, this would save thousands of lives as it would allow more people to be vaccinated. This...might work. Our leaders are currently trying to choose between a strategy that will definitely work to save many lives, or a strategy which could save more lives but has some risk of not working. This is a fair calculation to make. Covid cases have been on the rise, with the average death rate in America being 2,661+ deaths a day. And Biden’s plan does take the need for a second dose into account, though patients would receive it later. That being said, scientists such as Dr. Anthony Fauci are opposed to this plan as, again, we can’t be certain this strategy would work as well. And that is assuming that vaccine production can be sufficiently sped up to get everyone their second dose in time. Personally, I would prefer to keep to the three-week vaccine schedule, as that is the position of the majority of scientists. But I acknowledge my own biases; this is a situation where a calculated risk can superficially resemble a misbegotten scheme and I don’t have enough information at this time to tell the difference. Biden has promised to give more information about his plan after his inauguration, at which point we will know more.
The scary part about this issue is the same thing that’s been scary about the pandemic as a whole; everyone is working with evolving information. We now have enough information to start combating the pandemic, but only just enough. Our use of limited information is often inflexible, especially when so many lives are on the line. But public policy and the application of knowledge requires flexibility, especially when so many lives are on the line. As of now, the CDC is insisting we keep to the three week vaccine schedule and is assuring us that vaccine distribution will improve in the coming months as infrastructure improves. There have been a few scientists who have come out in support of giving everyone one dose, but the scientific consensus still appears to be in favor of the existing vaccine schedule. That could change as we find new data on antibody responses and vaccination plans become more fleshed out.
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