Tuesday, October 26

Travel bans are not an effective response to the new variant of Covid | Coronavirus

secondNow we all know that a new variant of Sars-CoV-2, the virus that causes Covid-19, has been detected in the UK and is spreading rapidly. Chris Whitty, England’s chief medical officer, announced that the variant, called B.1.1.7, it is up to 70% more transmissible according to modeling studies. B.1.1.7 caused many infections in south-east England in a short period of time, rapidly displacing other circulating variants. Patients infected with B.1.1.7 also had higher viral loads. While this is certainly concerning and warrants urgent scientific investigation, the data supporting that this variant alone is driving the associated increase in cases is preliminary and inconclusive. However, politicians began to implement radical policies immediately.

Several countries They have imposed travel bans, greatly reducing travel from the UK or blocking it entirely. France closed its borders to most of the transport of goods. New York Governor Andrew Cuomo, called the United States government to impose numerous restrictions, including a travel ban from Europe. The later placed for mandatory rapid tests for all travelers on flights to the US from the UK.

Given the high prevalence of all Sars-CoV-2 variants, including in the UK and many countries abroad, imposing onerous travel restrictions alone is unlikely to have a significant impact on the overall pandemic. Also, it may be too late. Variant B.1.1.7 Has been reported in other European countries as well as in Australia. These policies appear to be based more on fear of variants with unknown properties than on actual data, and are due to a persistent and fundamental misunderstanding of viruses and how they evolve and change when they spread through a population.

Genetic mutation, the process that drives all evolutionary adaptation, is normal and expected, particularly for viruses. Every time the virus copies its genetic material, called the genome, it can make a mistake. If that mistake is not corrected, it will copy itself the next time the virus replicates its genome. Mutations occur by chance, but if they occur in a critical location and give the virus an advantage that allows it to compete with other viral variants, they are said to be under positive evolutionary selection. For example, mutations in the peak protein Sars-CoV-2, which allows the virus to enter and infect cells, can be selected if they make the virus more efficient at establishing an infection.

We can probably hope to see other variants that may be more effective at spreading, causing disease, or bypassing our immune responses. We must be prepared to respond in an informed and thoughtful way, rather than react. Unfortunately, because Sars-CoV-2 is spreading so widely, the virus has many opportunities to develop mutations that give it a competitive advantage. The only way to stop the mutation of the virus is to take away its ability to replicate, which means drastically reducing community transmission.

Mutations do not automatically turn a virus into a more rare pathogen. The benefits conferred by positively selected viral mutations are good for the virus, but are not necessarily always bad for the human host. Many mutations can make the virus better infect cells, replicate, or spread to new hosts, but they will have no effect on the severity or type of disease they cause. In the case of B.1.1.7, fortunately there is no indication that the 23 mutations that distinguish the variant cause a more severe Covid-19.

The claim that B.1.1.7 is more transmissible is based primarily on epidemiological evidence and data on increased viral load, and it is compelling but far from decisive. To show conclusively that B.1.1.7 is more transmissible, it is necessary to quantify it experimentally in animal models of Sars-CoV-2 transmission. Even if B.1.1.7 turns out to be more transmissible, it is not likely to be transmitted differently than all other circulating Sars-CoV-2 variants. It has not acquired viral superpowers that make existing precautions irrelevant, and it is still spread primarily through inhalation or direct contact with infectious respiratory droplets and aerosols.

One thing that is unlikely to have much of an impact is the kind of travel ban that is apparently imposed to prevent the export of B.1.1.7 from the UK. This reflects a simplistic understanding of how viruses spread and evolve, as well as how we detect the emergence of potentially consequential new variants such as B.1.1.7. The UK is a world leader in genomic surveillance, the practice of sequencing the genomes of viruses that cause new cases. It is likely that B.1.1.7 is already circulating in other countries, and has simply not been detected yet due to the already high prevalence of Sars-CoV-2 and less comprehensive genomic surveillance. Draconian measures can foster panic and make the situation worse. When the UK domestic travel ban and restrictions were announced, passengers full Train station platforms and crowded carriages must leave London before applying Level 4 restrictions, creating conditions conducive to the spread of the virus.

Rather than harsh and largely ineffective travel bans, we should focus on encouraging adherence to proven interventions such as masking, distancing, avoiding crowds and confined spaces, avoiding gathering outside the home or quarantine group, and practicing good hand hygiene. . By emphasizing the additive nature of risk reduction, transmission can be reduced in a way that empowers people with the information to make good decisions to protect themselves and their families.

Although we still don’t know for sure whether B.1.1.7 is substantially more communicable, we do know that the pandemic is out of control in most of the world. We must balance scientific uncertainty with reasonable approaches that we already know are effective in reducing community transmission, regardless of what we learn about B.1.1.7. Dramatic measures implemented through fear and uncertainty miss the opportunity to increase participation in measures known to reduce transmission, regardless of a virus’ innate propensity to spread to new hosts. We have already suffered unacceptable losses from Covid-19. To truly contain the pandemic, leaders and lawmakers must calmly educate and engage the public, rather than risk panicking through confusing and inconsistent measures.


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