As the year 2020 ended and the world witnessed an unprecedented global pandemic, we were starting to think of vaccines as a light at the end of the tunnel. Now comes news of new variant strains of SARS-CoV-2 that have been described in the United Kingdom and other countries. The UK variant is referred to as "SARS-CoV-2 VOC 202012/01" or more commonly, as "B.1.1.7."
Massive efforts have been initiated including Tier 4 lockdown measures in parts of the UK, while scientists labor to understand whether this strain is more rapidly transmissible than others now circulating. At this time, there is no evidence that the new UK variant causes more severe illness or increases risk of death. Investigations are underway to define the variant and information is coming out on its transmissibility, the effect on mortality, immunity, and vaccine effectiveness.
How is this variant different from the originally identified strain?
B.1.1.7 has 17 mutations among which eight are located in the spike protein. Three of these mutations have potential biological significance.
An important observation is the mutation in the receptor binding domain of the spike protein at position 501. This mutation is called N501Y.
What is important about N501Y?
Earlier studies on variants with N501Y suggest that they may bind more strongly to the human angiotensin-converting enzyme 2 (ACE2) receptor. Although it is still not known whether tighter binding translates into any significant epidemiological or clinical differences, the possibility of easier entry of this variant into human cells exists.
Is this new variant related to the newly identified variant in South Africa?
Probably not. The South African government recently announced the emergence of a new strain similar to that in the UK. While the South African variant also has the N501Y mutation and several other mutations, it emerged completely independently of the UK strain and is not related to it.
What implications could the emergence of the new UK variant have?
Among the potential implications, the following are important:
- Can spread more quickly in humans
In lab experiments, scientists determined that even a single amino-acid change in the viral genome can allow the coronavirus to propagate more quickly in human respiratory epithelial cells. British researchers and public officials have reported B.1.1.7 to be more transmissible than other versions of the coronavirus — with estimates ranging from 50% to 70% more infectious. No experimental data is yet available on B.1.1.7.
- Can cause either milder or more severe disease in humans
Until now, there has been no evidence that B.1.1.7 produces more severe illness than other SARS-CoV-2 variants. However, in South Africa, the variant is spreading quickly through coastal areas, and in preliminary studies, doctors there have found that people infected with this variant carry an increased viral load. In many viral diseases, this is associated with more severe symptoms.
- Can evade detection by specific diagnostic tests
Most commercial PCR tests use multiple targets to detect the virus, such that even if one of the targets is changed, the other PCR targets will still work
- Decreased susceptibility to therapeutic agents such as monoclonal antibodies
Right now, we have no data to confirm this.
- Can evade vaccine-induced immunity
FDA-authorized vaccines are "polyclonal," producing antibodies that target several parts of the spike protein. The virus would likely need to accumulate multiple mutations in the spike protein to evade immunity induced by vaccines or by natural infection. Both the Pfizer/BioNTech and Moderna vaccines are being tested to identify any effects on efficacy.
What does this mean for the future and the role of a vaccine against this new variant?
Using mathematical models, a recent research by Davis et al. (2020), estimated that the novel SARS-CoV-2 variant B.1.1.7 could be more transmissible than existing circulating SARS-CoV-2 viruses. However, this study did not find evidence that the new variant is associated with higher disease severity.
Right now, most experts don't think that the variant will be able to evade vaccines. The leading vaccines were designed to teach the immune system to make antibodies that can recognize and block the spike proteins, so it's possible that changes to the spike could alter how well the vaccines work.
The chart shows why this new variant is so concerning as COVID cases spike in the UK drastically from December to January.
However, our immune systems can produce a range of antibodies against a single viral protein, making it less likely that viruses can easily escape their attack.
The same could occur with antibodies generated by an initial case of Covid-19. Wendy Barclay, the head of infectious diseases at Imperial College London, said at a briefing that: "There's a chance that the antibodies that were made in the first infection won't work as well against the new variant." But Barclay emphasized that the immune system has other components that contribute to protection, including T cells that can also recognize and destroy the virus. She also noted that vaccines help generate antibodies that can target different parts of the spike protein and take different approaches to fighting off the virus. So even if some loss occurred in the ability to target the spike, the vaccines have other ways to block the virus. It would be unlikely that the current changes in the variant could overcome all those layers.
One other concern that has come up with the new variant is the effect on children. According to the American Academy of Pediatrics (AAP) the number of coronavirus cases in children has seen a surge by 25% between December 3 and 17. The latest report by AAP said that more than 1.8 million children across the US have tested positive for the novel coronavirus since the beginning of the pandemic. "There is a hint that it has a higher propensity to infect children," said Neil Ferguson, a professor and infectious disease epidemiologist at Imperial College London.
If the B.1.1.7 or another variant ends up being more transmissible, massive vaccination efforts will be needed to spread its spread worldwide.
As of now, public health measures still remain the best protection - wearing masks, face shields, gloves, maintaining social distancing, avoiding family gatherings, public transportation whenever possible, and sharing indoor spaces with strangers.
The author is Senior Laboratory Director of Praava Health