We have been hearing about several new strains of the SARS-CoV-2 virus that causes COVID-19. There may be hundreds or even thousands of variants of the virus, although most may confer no evolutionary advantage and just die out.
Of course, there are only a handful of new COVID-19 strains that are actually dangerous, but the issues are whether the new vaccines from Pfizer, Moderna, JNJ, and AstraZeneca confer immunity to these new strains and what regulatory requires may be necessary for the vaccine manufacturers to respond to them.
Let’s take a quick review of these new COVID-19 virus strains and what we know about vaccine effectiveness against them.
The new COVID-19 virus strains
There are three main SARS-CoV-2 variants that are most concerning to the CDC as of today (and as we know with this pandemic, in a week, who knows what will be concerning):
- B.1.1.7 – In the United Kingdom (UK), a variant of SARS-CoV-2 known as B.1.1.7 emerged. This variant carries a large number of mutations and has since been detected around the world, including in the United States (US). This variant was first detected in the US at the end of December 2020. In January 2021, scientists from the UK reported early evidence that suggests the B.1.1.7 variant may be associated with an increased risk of death compared with other variants. More studies are needed to confirm this finding.
- B.1.351 – In South Africa, another strain of SARS-CoV-2 known as B.1.351 emerged independently of B.1.1.7. According to a non-peer-reviewed preprint article, this variant shares some mutations with B.1.1.7. Cases attributed to B.1.351 have been detected outside of South Africa, and this variant was first detected in the US at the end of January 2021. Preliminary evidence from non-peer-reviewed publications suggests that the Moderna COVID-19 mRNA vaccine currently used in the US may be less effective against this new strain.
- P.1 – In Brazil, a variant of SARS-CoV-2 known as P.1 was first identified in January 2021 in travelers from Brazil who arrived in Japan. This variant was detected in the US at the end of January 2021. There is evidence to suggest that some of the mutations in the P.1 variant may affect the ability of antibodies (from natural infection or vaccination) to recognize and neutralize the virus.
Mutations in viruses occur naturally over time whenever an animal or human is infected by that virus. Some viruses, such as influenza, have a fairly high rate of mutation, while others do not.
While the SARS-CoV-2 virus spreads, a certain level of genetic mutations occurs over time. Many mutations have no effect on the infectivity or the danger from the virus. Some mutations, in fact, many of mutations are deleterious, and that strain may die out. However, some mutations, like the ones listed above, cause these new COVID-19 strains to outcompete others because the mutations are more beneficial to the virus.
In addition, the mutation rate for coronaviruses is significantly lower than influenza viruses, which recombine frequently into different strains that are unknown to the immune system, despite vaccination or prior infection. That’s why the flu keeps coming back every season.
The CDC and other public health agencies closely monitor these new COVID-19 strains because the might be dangerous. Thus, they attempt to determine the following as quickly as possible:
- The ability of the new COVID-19 strain to spread more quickly in people.
- The ability of the new strain to cause either milder or more severe disease in people.
- The ability to evade detection by specific diagnostic tests.
- Decreased susceptibility to therapeutics that employ monoclonal antibodies. Monoclonal antibody therapy requires specifically designed antibodies that target unique regions of the virus to block its replication or infection. If a new mutation causes the virus to avoid the antibody, then the therapy may be less effective.
- Ability to evade natural or vaccine-induced immunity. This may be quite rare because the typical immune response, which employs polyclonal antibodies, targets various parts of the antigenic portions of the virus. It would take several mutations to reduce the natural or vaccine-induced immunity, but it’s important to monitor these mutations in case the new COVID-19 strains begin avoiding the immune response.
How do the vaccines work against the new COVID-19 strains
Right now, we don’t have huge clinical trials to support the effectiveness against the new COVID-19 strains for the four currently (or nearly currently) available COVID-19 vaccines from Pfizer, Moderna, AstraZeneca, and JNJ (Johnson and Johnson).
However, as I wrote above, these vaccines induce polyclonal antibodies so the body’s antibodies will attach to several different parts of the S-protein, the spike that causes the SARS-CoV-2 virus to attach to cells. Thus, it would take a lot of mutations to that spike before vaccines become ineffective.
This does not mean that we should not be concerned about the new variants, but there is no reason to currently believe that the four vaccines that may be available in the USA and Europe will be ineffective.
However, that being said, the B.1.351 variant from South Africa may not be as neutralized as well by antibodies elicited by the vaccines. Right now, we don’t if any or all of the vaccines are effective against that variant.
Without a ton of evidence (or any good evidence at all), it appears that the mRNA vaccines from Pfizer and Moderna perform better against the new COVID-19 strains compared to the adenovirus-based vaccines from JNJ and AstraZeneca. But there are so many differences between the two classes of vaccines, it’s hard to tell.
However, the good thing about the mRNA vaccines is that they can be easily reformulated to deal with new SARS-CoV-2 variants. The sequence for a newly mutated S-protein on the virus can be isolated to create a new mRNA fragment for a revised vaccine. This can be done very quickly.
The FDA has decided that they will permit immunogenicity data, booster studies to support “strain changes” to an authorized COVID-19 vaccine rather than requiring new, large clinical trials. This decision will allow amendments to the Emergency Use Authorizations for the vaccines.
To forestall anti-vaccine activist gripes about this, this change doesn’t mean that the FDA will overlook any safety or effectiveness issues. As long as there are no other changes to the vaccine except for the “strain change,” the evidence supporting its safety doesn’t change.
This is similar to the flu vaccine, where a full clinical trial isn’t required as long as the only change to the vaccine is the antigen. Because COVID-19 is so deadly, it is important that we respond to new COVID-19 strains as quickly as possible to prevent.
However, irrespective of the current vaccine’s effectiveness against these various strains, transmission of SARS-CoV-2 between humans is what causes new mutations, because more infective and potentially deadly variants are selected for. By vaccinating a large proportion of the population against the disease, it causes the mutation rate to decrease. And with fewer variants, the vaccines work better. It’s a positive feedback loop.
I think that if you speak to experts on this disease they are confident in the vaccines ability to fight against the new mutations, but I’m sure they lose sleep at night that new variant arises that avoids the immune responses of those who were vaccinated or contracted the disease. I lose sleep because of that concern.
But for the time being, I think the evidence probably supports the effectiveness of the four vaccines against the diseases. However, because we can’t be sure, that means public health initiatives, like facemasks and social distancing, still need to be followed. But the pharmaceutical companies behind the vaccines are preparing for “just in case.”
Notes
I need to clarify the terminology I use in this article. COVID-19 is a disease caused by the SARS-CoV-2 virus. Technically, COVID-19 does not mutate, just the virus.
In addition, mutations, strains, and variants are somewhat interchangeable terms that describe different viruses. However, the mutation is a technical change in the DNA, while variants and strains can be considered subspecies (or sub-subspecies) of the coronavirus. So, calling it a COVID-19 variant or strain is accurate, it is technically not how we should describe it.
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