Spring has sprung up, and relief is felt in the air. After a year of locking up and social distancing, more than 171 million doses of COVID-19 vaccine have been administered in the U.S. and about 19.4% of the population has been fully vaccinated. But there is something else in the air: the ominous variants of SARS-CoV-2.
I am a virologist and a vaccinologist, which means that I spend my days studying viruses and devising and testing vaccine strategies against viral diseases. In the case of SARS-CoV-2, this work took on greater urgency. We humans are in a race to become immune to this kagei virus, whose ability to mutate and adapt seems a step ahead of our ability to gain herd immunity. Because of the variants that appear, it could be a race to the wire. https://www.youtube.com/embed/fp-oG7ZWOJI?wmode=transparent&start=0 The variant in Brazil is flooding the health system in the country.
Five variants to watch
RNA viruses like SARS-CoV-2 are constantly mutating as they make multiple copies of themselves. Most of these mutations end up being unfavorable to the virus and therefore disappear by natural selection.
However, they occasionally offer the benefit of a mutated or so-called genetic variant virus. An example would be a mutation that improves the ability of a virus to bind more tightly to human cells, thereby improving virus replication. Another would be a mutation that allows the virus to spread more easily from person to person, thus increasing transmission.
None of this is surprising for a virus that has just arrived in the human population and is still adapting to humans as hosts. Although viruses do not think, they are driven by the same evolutionary urge as all organisms – their first business order is to perpetuate.
These mutations have resulted in several new SARS-CoV-2 variants, leading to clusters and, in some cases, global spread. They are broadly classified as variants of interest, concern, or great consequence.
There are currently five worrying variants circulating in the US: B.1.1.7, which originated in the UK; B.1.351, of South African descent; P.1., First seen in Brazil; and B.1.427 and B.1.429, both of California origin.
Each of these variants has a number of mutations, some of which are key mutations in critical regions of the viral genome. Because spike protein is required for the virus to bind to human cells, it carries a number of these key mutations. In addition, antibodies that neutralize the virus typically bind to a protein class, making the class sequence or protein a key component of the COVID-19 vaccine.
India and California have recently discovered variants of “double mutants” that, although not yet classified, have gained international interest. They have one key mutation of the spike protein similar to that found in the Brazilian and South African variants, and another already in variants B.1.427 and B.1.429 California. As of today, no variant has been classified as a major consequence, although there are concerns that this could change as new variants emerge and we learn more about variants already circulating.
More transmission and worse disease
These variants are worrying for several reasons. First, the worrying variants of SARS-CoV-2 are generally more easily spread from person to person by at least 20% to 50%. This allows them to infect more people and spread faster and wider, eventually becoming the predominant strain.
For example, variant B.1.1.7 UK that was first discovered in the US in December 2020 is now the predominant strain in the US, accounting for about 27.2% of all cases by mid-March. Likewise, variant P.1, first discovered in travelers from Brazil in January, is now ravaging Brazil, causing a health system collapse and leading to at least 60,000 deaths in March.
Second, worrying variants of SARS-CoV-2 can also lead to more serious illnesses and increased hospitalizations and deaths. In other words, they may have increased virulence. Indeed, a recent study in England suggests that variant B.1.1.7 causes more severe disease and mortality.
Another concern is that these new variants may avoid immunity caused by natural infection or our current vaccination efforts. For example, antibodies from people who have recovered from an infection or who have received a vaccine may not be able to bind so effectively to a new variant of the virus, resulting in reduced neutralization of that variant of the virus. This could lead to re-infections and reduce the effectiveness of current treatments with monoclonal antibodies and vaccines.
Researchers are intensively investigating whether the effectiveness of the vaccine against these variants will be reduced. Although most vaccines appear to remain effective against the UK version, one recent study found that AstraZeneca lacked efficacy in preventing mild to moderate COVID-19 due to the South African variant B.1.351.
On the other hand, Pfizer recently published data from subgroups of volunteers in South Africa who support the high efficacy of their mRNA vaccine against variant B.1.351. Another encouraging piece of news is that T-cell immune responses elicited by natural SARS-CoV-2 infection or mRNA vaccination are recognized by all three versions in the UK, South Africa and Brazil. This suggests that even with reduced neutralizing antibody activity, T-cell responses stimulated by vaccination or natural infection will provide some level of protection against such variants.
Stay awake and get vaccinated
What does all this mean? Although current vaccines may not prevent mild symptomatic COVID-19 induced by these variants, they are likely to prevent moderate to severe disease, particularly hospitalizations and deaths. That’s good news.
However, it is imperative to assume that current variants of SARS-CoV-2 are likely to continue to evolve and adapt. In a recent study among 77 epidemiologists from 28 countries, most believed that current vaccines should be updated within a year to better handle new variants, and that low vaccine coverage is likely to facilitate the emergence of such variants.
What should we do? We must continue to do what we have been doing: using masks, avoiding poorly ventilated spaces, and practicing social distancing techniques to slow down transmission and deter further waves triggered by these new variants. We also need to vaccinate as many people as possible in as many places as possible and reduce the number of cases and the likelihood that the virus will generate new variants and escape the mutants as soon as possible. And for that, it is vital that public health officials, the government and non-governmental organizations address the variability and equality of vaccines at the local and global level.
ABOUT THE AUTHOR
Paulo Verardi is currently an Associate Professor of Virology and Vaccinology in the Department of Pathobiology at the University of Connecticut (UConn) and an investigator at the Center for Excellence for Vaccine Research (CEVR) at UConn. He holds a bachelor’s degree in biology from the Federal University of Rio Grande do Sul in Brazil and a doctorate in comparative pathology from the University of California, Davis. He joined UConn as an assistant professor in 2008. He is a member of the American Society of Virology (ASV), the American Society of Microbiology (ASM), the American Society of Immunologists (AAI), and the American Society of Gene and Cell Therapy (ASGCT). In 2013, he received the ASM Award for Outstanding Service to the Global Engagement Committee. Serves as a grant reviewer for the National Institutes of Health (NIH) since 2005. Verardi has a broad background in molecular biology, virology and immunology, with an interest in the development of vaccines and immunotherapeutic vectors. He has worked on immunomodulatory vaccinia genes, cytokines as immunosuppression and enhancement agents, the development of vaccinia-based vaccinia vaccines, safer and more effective smallpox and AIDS vaccine vectors, vaccines and the design of safer and diagnostic data for fever. Valley, foot – and – mouth disease, and swine reproductive and respiratory syndrome. More recently, he has worked on developing vaccine platforms for the rapid development and deployment of vaccines for new viruses and emerging threats such as Zika virus, SARS-CoV-2 and a number of other mosquito and tick-borne agents such as the Powassan virus.
This article is courtesy of the conversation.