January 7, 2021 – William Hanage, associate professor of epidemiology at the Harvard School of Public Health TH Chan, discusses two newly discovered variants of the coronavirus.
P: There are new reports of a second variant of the coronavirus in South Africa – in addition to the one found in the UK and other countries – which may have higher transmissibility than other strains. What can you tell us about these variants?
AN: First, let’s distinguish 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 really bad for the virus. These variants, however, have multiple mutations that distinguish them from the rest of the virus population.
In the past few months, we’ve seen two variants emerge. The first “concern variant” has been reported in the UK and evidence has accumulated in recent weeks that it is more transmissible. The second, the so-called “501.V2” variant, is spreading rapidly in South Africa. Other countries have reported the presence of both variants, which is probably the result of increased scrutiny and awareness. These two variants share some similarities, including a specific mutation that leads to a change in the spike protein that was found in vitro to increase the binding affinity of the coronavirus to the receptor that the virus uses to enter cells. In addition to this mutation, 501.V2 has several other mutations, including one that can help make the virus not so easily neutralized by convalescent sera, a treatment that uses blood obtained from an individual who recovered from COVID-19 and developed antibodies.
Q: How likely are other variants to appear with greater transmissibility and how likely are any of them to end up in the United States?
AN: It should be noted that the variants did not appear in a predictable way and appear to appear rarely. We know of two at the moment, and there have been more than 85 million cases of coronavirus worldwide. However, given the uncontrolled nature of the pandemic in many places, it is extremely likely that other variants will emerge and reach the United States. In fact, they may have already done this and we only saw those in the places where people were looking for them.
Genomic surveillance is poor in most places, including much of the United States. For example, when I recently looked at nextstrain.org – a site that tracks the evolution of the pathogen and gathers genomic data from global sources – and searched for North Dakota SARS-CoV-2 genomes, I didn’t find any, although North Dakota had 4º in the country for per capita mortality at the time. It must be a scandal that we know so little about the virus that circulates there.
P: To what extent can we be sure that the vaccines currently available will be effective against any new variants? And what would be the most important strategies to prevent the rapid spread of these variants?
AN: At the moment we have no evidence that there will be a decrease in the effectiveness of available vaccines. The concern variant reported in the UK does not seem more likely to reinfect those we know were previously infected, suggesting that vaccines will be effective. 501.V2 has some mutations that have been reported elsewhere to escape elements of the immune response, but it is not clear whether its success is related to this or greater infectivity. It is important to note that vaccines work with various parts of the immune system and, therefore, even if one is reduced, the others must still be active.
In the meantime, to prevent the spread of these variants, we must make sure that we know where they are and be ready to respond. So we must be prepared to enact stronger restrictions. It is important to note that in the UK the variant became very common in the south east of the country in November, a period when there were relatively severe restrictions. Finally, we need to vaccinate. All this amazing scientific work to produce the vaccines is worthless if we don’t overcome distribution problems and get people to take them.
– Karen Feldscher