January 7, 2021 – William Hanage, associate professor of epidemiology at Harvard TH Chan School of Public Health, discusses two newly discovered coronavirus variants.
Q: New reports are pointing to a second variant of the coronavirus in South Africa – in addition to that found in the UK and other countries – which may have higher transmissibility than other strains. What can you tell us about these variants?
A: Let’s start by distinguishing between “mutations” and “variants”. Mutations are specific changes in the viral genome. They happen all the time and most don’t make a big difference, or are actually bad for the virus. These variants, however, have multiple mutations that set them apart from the rest of the viral population.
In recent months, we have seen two variations emerge. The first ‘worrying variant’ was reported in the UK and in recent weeks evidence has accumulated that it is more transmissible. The second, the so-called “501.V2” variant, spread rapidly in South Africa. Other countries have reported the presence of both variants, which is likely the result of increased review and awareness. These two variants share some similarities, including a specific mutation leading to a change in the spike protein that was found in vitro to improve the binding affinity of the coronavirus with the receptor used by the virus to enter cells. In addition to this mutation, 501.V2 has several other mutations, including one that may help make the virus less easily neutralized by convalescent sera, a treatment that uses blood obtained from an individual who has recovered from the virus. COVID-19 and developed antibodies.
Q: To what extent do you think there will be other emerging variants that have higher transmissibility, and what is the likelihood that any of them will end up in the United States?
A: It should be noted that the variants did not appear predictably and seem to occur rarely. We know of two at the moment and there have been more than 85 million cases of coronavirus worldwide. However, given the out-of-control nature of the pandemic in many places, it is extremely likely that other variants will emerge and reach the U.S. Indeed, they may have already and we have not seen than those in places where people were looking for them.
Genomic surveillance is poor in most countries, including much of the United States. For example, when I recently visited nextstrain.org – a website that tracks the evolution of pathogens and gathers genomic data from global sources – and researched the SARS-CoV-2 genomes from North Dakota, couldn’t find any, even though North Dakota was 4 years olde in the country for per capita mortality at the time. It should be a scandal that we know so little about the virus circulating there.
Q: How confident can we be that the vaccines currently available will be effective against any newer variants? And what would be the most important strategies to avoid the rapid spread of these variants?
A: At this time, we have no evidence that the effectiveness of available vaccines will be reduced. The worrying variant reported in the UK does not appear to be more likely to re-infect those we know were previously infected, suggesting the vaccines will be effective. 501.V2 has some mutations that have been reported elsewhere to evade elements of the immune response, but it is not clear whether its success is related to this infectivity or to greater infectivity. It is important to note that vaccines work with several parts of the immune system, and so even if one is weakened, the others should still be active.
In the meantime, to prevent the spread of these variants, we need to make sure we know where they are and be prepared to respond. Then we have to be prepared to adopt more stringent restrictions. It should be noted that in the UK, the variant became very common in the south-east of the country in November, a time when relatively severe restrictions were in place. Finally, we need to vaccinate. All of this amazing scientific work to produce the vaccines counts for nothing if we don’t overcome the distribution problems and get people to take them.
– Karen feldscher