With variants of Covid-19 in the news more, I thought it would be beneficial to provide more information about these variants. Some of this material was covered in a previous post, but here I’ll go into more detail.
Viral Mutation
I’ve talked about viral mutation in the past, but to review; every time a virus has its genetic material copied in order to reproduce, small mistakes get made. Most of these mistakes don’t affect the new viruses, some might weaken the new virus, but occasionally, a mutation will occur that gives this new virus a special advantage. Because Covid-19 is so widespread within the population and viruses reproduce so quickly, there are a lot of opportunities for these advantageous mutations to occur. A single infected cell can produce hundreds or even thousands of new viruses and a single infected person can produce 1011 individual virions. Over time, mutations will build up as the descendants of mutated viruses acquire their own mutations, becoming significantly different from the wild-type (most common) form of Covid-19.
If one virus happens to accumulate enough advantageous mutations to become significantly distinct from the original version, scientists may regard it and its descendants as a new strain. These differences can take the form of an increased speed of spread, more severe (or less severe) illness, being less detectable with existing diagnostic tests, or even being less affected by existing immune responses. Any of these differences has a potential risk of worsening the pandemic, likely by putting greater strain on our already overburdened medical infrastructure, but possibly by making viruses just different enough that our existing vaccines offer imperfect protection against them. So, how likely are these risks?
One thing that health departments in every country has been doing during this pandemic is genomic surveillance. The CDC currently receives 750 samples of SARS-CoV-2 a week from state health departments and other public health agencies from across the United States, just as all other national health agencies are doing in their respective countries. The CDC, along with the labs of universities and private contractors, sequences the genomes of these samples. All this genomic data allows these agencies to monitor the emergence of unique strains, determine the changes in their behavior caused by their new mutations, and follow these new strains as they spread throughout the population. This monitoring allows governments to plan in advance for the challenges created by these new strains.
As of now, there are numerous major SARS-CoV-2 variants that are being monitored. Five you might have heard of are:
B.1.1.7, also called the UK variant, which has been covered here before. Initially emerging in Kent, England in September 2020, it has since spread throughout the world. It contains several mutations to the virus’ spike protein, causing this protein to fold itself into a slightly different shape. This new shape makes the virus better able to grab hold of and enter cells, thus causing more infections and becoming more virulent. It spreads faster and recent research suggests it might carry a higher chance of death. That said, there is no evidence that any of the Covid vaccines are less effective against this strain. (Darker countries have more confirmed cases)
B.1.351, also known as the South Africa variant. Initially detected in the Eastern Cape of South Africa in October 2020, it has since spread internationally, but not quite globally (see maps below, darker countries have more confirmed cases). It has many of the same mutations as the UK variant, (certain mutations are very common due to them occurring easily and causing significant improvements to the virus) causing this strain to spread faster. But it also has a specific mutation called E484K, which makes it slightly harder for Covid antibodies to attach to the spike protein. This would in theory make this strain somewhat resistant to many of the Covid vaccines, and there has been recent evidence to back this theory up. Research is still being done for each of these vaccines into just how resistant this strain is, but it’s important to remember that less effective is not the same as ineffective.
P.1, also known as the Brazil variant. Initially detected in the Amazonas region of Brazil in January 2021, it has since spread internationally, but not quite globally (see maps below, darker countries have more confirmed cases). It has mutations in common with both the UK and South Africa variants, including E484K. It’s still relatively new, so data is still somewhat limited, but it appears to spread faster, be somewhat more deadly, and is somewhat resistant to existing Covid vaccines. It is still under observation.
B.1.526, also known as the New York variant. Initially detected in Manhattan in November 2020, it now accounts for one-fourth of new Covid cases in New York City and has been found in fourteen other American states. It appears to spread faster than wild-type Covid and might have some resistance against existing vaccines. There is still much to learn about this strain (it only recently saw significant spread) and some are concerned that it could be a major threat, especially in New York where there might be another surge of cases. For now at least, it seems somewhat contained to the United States.
CAL.20C, also known as the California variant. Initially detected in Southern California in late 2020, it now accounts for half of new Covid cases in Los Angeles and appears to have spread internationally (it was recently detected in Denmark). On top of many of the same mutations as the previous four variants, this strain also has a mutation, L452R, that hasn’t been seen before in any other variant. This makes it harder to determine what exact effect it will have on this new strain, but evidence does seem to support that this variant spreads faster. It is still under observation.
All of these variants have still infected far fewer people in total than wild-type SARS-CoV-2, just by virtue of the original virus being far more widespread for longer, so you’re far more likely to catch it than any of the new strains. That said, these variants could come to pose a larger threat as they continue to spread and mutate further. Already, there have been a few instances of the UK variant identified with the E484K mutation, possibly being the start of a brand new distinct strain with greater vaccine resistance. This is one more reason why it is so important to get vaccinated. As more people get vaccinated, the virus won’t be able to spread as fast and as far. This means there are fewer opportunities for new mutations and the creation of new strains. Even if a vaccine doesn’t provide enough protection to make an inoculated person immune to a variant, it can still offer enough protection to create herd immunity, which can cause these variants to slowly dwindle away. And the manufacturers of the existing vaccines have started development of vaccines for these distinct variants, which could contain them much faster. Until that time, it will be important to continue wearing masks, social distancing, and listening to the public health experts who continue to track these variants and recommend policy based on these observations in the interest of public health.
Myth Dispelled
On a final but largely unrelated note, I would like to clear something up. I have recently seen some misinformation going around that the Covid-19 vaccines don’t count as real vaccines because they don’t provide total immunity. This is...weirdly semantic and entirely untrue. The official definition of a vaccine is a drug that causes an antibody response to an infectious disease. A good vaccine, one that would get significant public usage, will cause an immune response equal to or better than the one created by said infectious disease, just without the dangerous effects of a real illness. Now, it is true that no vaccine will be 100% effective in every instance, just as an actual viral infection won’t cause complete immunity in every single instance. Some diseases are better able to evade the immune system, some people’s immune systems aren’t perfectly able to create a strong immune response, and, very rarely, someone gets profoundly unlucky. But the lack of absolute, perfect certainty, a common theme in life, doesn’t mean vaccination isn’t the best tool our society has against disease or a boon for virtually every individual. Feel free to look at any of my previous posts on this topic for additional information. In any case, no biologist or medical professional has any other definitions for vaccines.
Hi Will - congrats on your almost 1-year anniversary of blogging! I saw this and thought of you: https://news.psu.edu/story/663131/2021/07/07/research/fighting-covid-covid?utm_source=newswire&utm_medium=email&utm_term=663410_HTML&utm_content=07-08-2021-21-40&utm_campaign=Penn%20State%20Today