What do we know about the new U.K. COVID strain?
Last week, a new COVID strain was reported in the U.K. The news of the strain brought widespread panic across the world. How contagious is this new strain? What does it mean for the vaccines currently being deployed? Here’s a breakdown of what we know so far.
The Strain is Already Widespread
Experts agree that the novel strain is likely already present in other countries. The variant has been around in England since November 2020, and likely accounts for 60% of the new infections in the U.K. In the U.S., only a small percentage of COVID viruses are sequenced; given the frequency of travel between the U.K. and the U.S., it is likely that the sequence is already present in the U.S. but has yet to be detected.
Mutations in COVID-19
Sequencing identified 23 mutations in the viral genome. What does this mean exactly? When thinking about how this impacts the virus itself, recall that changes in DNA leads to differences in the mRNA it is transcribed into. This can potentially change the proteins that the mRNA encodes for.
Of the mutations identified, 14 alter the amino acids that are encoded for, and therefore are protein-altering. 3 are deletions, which can also alter the protein encoded for. Some of the mutations cause a change to the spike protein. To understand more how deletions and mutations alter proteins, see the bottom of the article for a brief breakdown of protein synthesis.
Implications on Spread and Vaccine Development
The current vaccines target many parts of the spike protein. As a result, experts believe that the current vaccines will continue to be effective against the novel strain. It is thought that it will take much longer for enough mutations to occur in the spike protein for the current vaccines to be rendered ineffective.
One of the mutations in this strain also makes it more transmissible than the original strain of COVID-19. Experiments run in a lab have shown that strains with this particular mutation outcompeted the viruses without the mutation. So far, case reports have shown this strain to spread rapidly, but have not shown that it is more severe or deadly than the previous COVID-19 strain.
Fortunately, our testing strategies will still work with this variant. The mutations may affect one target of testing, however, the other targets will still be able to be identified.
What needs to happen next?
Genomic surveillance is key in staying ahead of the virus. Thankfully, this mutation does not look like it will be detrimental to our testing or vaccination efforts. However, continued sequencing of viral strains will allow us to ensure we aren’t blindsided by a strain that can evade these efforts. Resources should be, naturally, allocated towards testing and sequencing.
What about travel bans? Well, we’re in a sense back to where we were in March. Travel bans were imposed on China, though we know now that the virus had been circulating in the U.S. for over a month at that point. The same is likely true now. Rather than focusing on a travel ban, we should probably focus on ensuring testing is widespread enough that people can test prior to and after travel. Masks should continue to be worn, and quarantines should continue to be observed until a negative test in a reasonable post-exposure timeframe can be achieved.
Bio Lesson: How does Protein Synthesis Occur?
DNA can contain one of four bases: adenine, thymine, guanine, cytosine. The mRNA contains one of four bases: adenine, uracil, guanine, cytosine. When DNA is transcribed, a complimentary sequence is generated: the mRNA. A and T are complimentary, as are G and C. However, there are no T’s in mRNA. All the T’s in an mRNA sequence become U’s. If the DNA reads ATGC, then the mRNA when transcribed will have the “complimentary sequence” of UACG.
When the mRNA is translated to protein by the ribosome, it is read 3 bases at a time. The 3 base sequences correspond to amino acids. You can see all the combinations in this table. You can see that each amino acid has multiple 3 base sequences that correspond to it. This means that sometimes, if a base gets changed via a mutation, there may be cases in which the amino acid actually remains the same.
Deletions or insertions in the DNA sequence can cause bigger changes depending on where in the sequence the deletion occurs. Since the mRNA is read 3 bases at a time from left to right, if a deletion occurs early in the sequence, the entire sequence of amino acids will get impacted. A good description of how mutations can impact sequence can be found here.
Changes in DNA directly leads to changes in the mRNA sequence. Changes in the mRNA sequence can lead to changes in the amino acid sequence, which can lead to major differences in the protein, depending on the properties of the amino acid deleted and the one that replaced it.