Spring has arisen and there is a feeling of relief in the air. After a year of blockade and social distancing, more than 171 million doses of COVID-19 vaccine have been administered in the US and about 19.4% of the population is completely vaccinated. But there is something else in the air: nefarious variants of SARS-CoV-2.
I am a virologist and vaccinologist, which means I spend my days studying viruses and designing and testing vaccine strategies against viral diseases. In the case of SARS-CoV-2, this work has taken on greater urgency. Humans are in a race to become immune to this gabion virus, whose ability to mutate and adapt seems to be a step ahead of our ability to gain immunity from the herd. Because of the variants that are emerging, it could be a race to the wire.
Five variants to see
RNA virus as SARS-CoV-2 constantly mutate as they make more copies of themselves. Most of these mutations end up being disadvantageous to the virus and therefore disappear through natural selection.
Occasionally, however, they offer a benefit for the mutated virus or so-called genetic variant. An example would be a mutation that improves the virus’s ability to attach more closely to human cells, thus improving viral replication. Another would be a mutation that allows the virus to spread more easily from person to person, thus increasing transmissibility.
None of this is surprising for a virus that is a newcomer to the human population and still adapts to humans as hosts. Although viruses do not think, they are governed by the same evolutionary impulse that all organisms have; his first order of work is to perpetuate himself.
These mutations have resulted in several new variants of SARS-CoV-2, which have led to groups of outbreaks and, in some cases, worldwide dissemination. They are generally classified into variants of high interest, concern, or consequence.
There are currently five worrying variants circulating in the US: B.1.1.7, which originated in the UK; the B.1.351., of South African origin; the P.1., first seen in Brazil; and B.1.427 and B.1.429, both native to California.
Each of these variants has a number of mutations, and some of these are key mutations in critical regions of the viral genome. Because the ear protein it is necessary for the virus to adhere to human cells, as it entails a number of these key mutations. Besides, neutralizing antibodies the virus typically binds to spike protein, thus making the spike sequence or protein a key component of COVID-19 vaccines.
India and California have recently detected “double mutant” variants which, although not classified, have gained international interest. They have a key mutation in the ear protein similar to one found in the Brazilian and South African variants, and another already found in the California variants B.1.427 and B.1.429. To date, no high-consequence variants have been classified, although the concern is that this may change as new variants appear and we learn more about the variants that are already circulating.
More transmission and worse disease
These variants are worrisome for several reasons. First, worrying variants of SARS-CoV-2 generally spread from person to person at least 20% to 50% more easily. This allows them to infect more people and spread more quickly and widely, eventually becoming the predominant strain.
For example, variant B.1.1.7 of the United Kingdom, which was first detected in the United States in December 2020, is now the prevailing circulating strain in the United States, representing a 27.2% of all cases are estimated for mid-March. Similarly, variant P.1 first detected in travelers from Brazil in January is wreaking havoc in Brazil, where it is causing a collapse of the health system and causing at least 60,000 dead in March.
Second, worrying variants of SARS-CoV-2 can also lead to more serious illnesses and increase hospitalizations and deaths. In other words, they may have increased virulence. In fact, a recent study in England suggests that the Variant B.1.1.7 causes more serious diseases and mortality.
Another concern is that these new variants may run away from the immunity caused by the natural infection or from our current vaccination efforts. For example, antibodies from people who recover from infection or have received a vaccine may not be able to bind so efficiently to a new variant virus, which will reduce the neutralization of that variant virus. This could cause reinfections and decrease the efficiency of the current monoclonal antibody treatments and vaccines.
Researchers are intensively investigating whether the effectiveness of the vaccine against these variants will be reduced. Although most vaccines appear to be effective against the UK variant, a recent study showed the AstraZeneca vaccine is not effective in preventing mild to moderate COVID-19 due to the South African variant B.1.351.
On the other hand, Pfizer has recently announced data from a subset of volunteers in South Africa who support high efficacy of its mRNA vaccine against variant B.1.351. Another encouraging news is that Immune responses of T cells caused by natural infection by SARS-CoV-2 or mRNA vaccination recognizes the three variants of the United Kingdom, South Africa and Brazil. This suggests that, even with a reduction in the neutralizing activity of antibodies, T cell responses stimulated by vaccination or natural infection will provide a degree of protection against these variants.
Be vigilant and get vaccinated
What does all this mean? Although current vaccines may not prevent the mild symptomatic COVID-19 caused by these variants, they are likely to prevent moderate and severe disease, and in particular hospitalizations and deaths. This is the good news.
However, it is imperative to assume that current SARS-CoV-2 variants are likely to continue to evolve and adapt. In a recent survey of 77 epidemiologists in 28 countries, most believed that in a year the current vaccines should be updated to better manage new variants and that low vaccine coverage they are likely to facilitate the emergence of these variants.
What shall we do? We must continue to do what we have been doing: use masks, avoid poorly ventilated areas, and practice social distancing techniques to slow down transmission and avoid new waves driven by these new variants. We also need to vaccinate as many people in as many places as soon as possible to reduce the number of cases and the likelihood that the virus will generate new variants and escape the mutants. And for that, it is vital that public health officials, governments and non-governmental organizations address vaccination and vaccine equity both locally and globally.