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We have begun discussing variants of SARS-CoV2 (the virus that causes COVID-19), which have been in the news. This is due to the fact that some particular variants are more contagious than the version of SARS-CoV2 that we’ll call the wild type, meaning not the version of the virus that first seems to have spread from bats to humans in in the Wuhan region of China, but the version that subsequently spread throughout the world. As we discussed in a previous post, a variant is simply any descendant of the virus that has accumulated enough mutations that make it different from the wild type in some way —either in the building blocks of proteins of the viral coat (one particular amino acid, a building block of proteins, can be substituted for a different one that was present in the same position on a protein) or in the way that the virus behaves. Any geographic location where the pandemic is spreading has variants, because spreading from person to person means that more little baby viruses are created, causing more mutations (changes in the genetic instructions in the viral RNA) over time, causing more variants, but researchers and health officials are on the lookout for particular variants that behave in a way that can make COVID-19 worse. This means SARS-CoV2 variants that are more contagious than the wild type, variants that can cause more severe disease than the wild type, variants that can cause symptoms in groups of people not affected as badly by the wild type (such as younger adults and children in whom the risk of developing severe symptoms has been much lower so far compared with elderly people and those with certain health conditions), and variants that can spread from, and cause, disease in people who have been immunized against the wild type by currently available vaccines, or by previous COVID-19 disease.
So far, in all of the new variants of concern, the same groups of people are at the highest risk, namely older people, males more than females, and those with certain health conditions, especially obesity, type 2 diabetes, and heart failure. No SARS-CoV2 variant is known that causes worse disease in young people akin to the influenza strain of the notorious 1918 flu pandemic in which young adults faired the worst. Nor has a variant been discovered that puts women at worse risk than men. But adding to the list of variants of concern in the United States that already includes the B.1.1.7, the B.1.351, and the P.1 that have emerged in other countries are some variants local to North American locations. Of these, in this post, we’ll focus on the California variant and the New York variant and see how they line up in comparison to the international variants mentioned above. We can do this, because there has been some research on the California and New York variants, although the data from such research remain to be published in peer-reviewed journals.
For perspective, just to review from a previous post, the B.1.1.7, the “UK variant” is of concern, as it is more contagious than the wild type, but it may or may not cause worse disease than the wild type for those who do get infected. In contrast, the B.1.351 (South African) and P.1 (Brazilian) appear to be more contagious and also cause worse disease. Doctors and scientists in the US are worried about B.1.351, because people have been infected with this variant in more than one location in the US. While P.1 has been devastating in Brazil, it has appeared in only a limited number of cases in the US, but, also has demonstrated that it can infect people who already have had COVID-19, caused by the wild type. Now enter from stage left and stage right the American variants: B.1.526 (New York) and the “California variant”, which is actually a pair of variants B.1.427 and B.1.429. As we have begun discussing in a previous post, but let’s drive home the point now, the susceptibility of variants to immunity from previous infection with SARS-CoV2 or from vaccination is graded; it’s a sliding scale, as is the effectiveness of vaccines. In attempts to understand the sliding scale of immune protection and virus/variant ability to cause disease and to spread, scientists are running various laboratory tests. One useful such test utilizes antibodies (or a serum, fluid containing antibodies, separated from blood) from people who have immunity to particular versions of SARS-CoV2, such as to the wild type, due to vaccination, or to previous infection. This is called a neutralization assay.
Although studies are on-going, research suggests that, compared with the antibody response that you develop from the vaccines approved thus far at the time that I am writing this in early March —Pfizer-BioNTech, Moderna, and Johnson & Johnson— the antibody response that you develop against the B.1.1.7 (UK) variant is equivalent, while the immunity that you develop against B.1.351 is about one sixth as robust. Scientists hypothesize that this is because of differences between B.1.351 and the wild type in a particular region of the spike protein, the protein that all of the vaccines are providing as the target practice for the immune system. Now, an antibody response one sixth as strong may sound scary, but such a partial response can make all the difference between a mild to moderate case of COVID-19 and a case that puts someone in the intensive care unit, or kills.
Furthermore —this is a very important concept for those who want to grasp where science is going with the variants and the vaccines— antibodies, which are made by specialized B lymphocytes called plasma cells— represent just one component of immune system defenses. In response to infection or to vaccination, the immune system response also includes other components, such as memory T lymphocytes and cytotoxic T lymphocytes (killer T cells). But the idea of the immunity one sixth as strong for the B.1.351 variant is based only on antibody studies. The situation is analogous to discussing the relative capability of a nation’s military and saying that it’s six times more effective against attack from one other nation versus attack from another, but the calculations have not yet considered your air force, or your navy.
This sets us up really nicely to consider the variants of New York, and especially California, because scientists have been studying those, and in the case of California, have released studies —albeit studies that still need to be peer-reviewed at the time that I’m writing this— based on antibody assays. Based on early results of studies, the California variant may be somewhat more lethal than the wild type (more likely to cause severe, life-threatening effects) as well as more contagious. Based on neutralization assays, the antibody response that the approved vaccines provide against the California is about one half of the response against the wild type SARS-CoV2, meaning about three times the response against the B.1.351 variant. Remember, this is not considering other aspects of immunity. That, plus studies of the numbers of cases and infections with the New York and California strains all hint strongly that, along the sliding scale, these American variants are somewhere intermediate between the wild type and the B.1.351 (South African) variant in terms of how much of a problem they will be as more people continue to be vaccinated. This also means that the three COVID-19 vaccines authorized so far, and which are available to pregnant women, should be very effective against these American variants.