Two new studies published in The Lancet differ from the accumulated evidence regarding the severity of COVID-19 caused by the British variant. As reported by the British magazine, the studies confirm that VOC B.1.1.7, predominant in many places, is more communicable, but is not associated with the development of a more serious or more lethal disease. The authors acknowledge that these findings contradict previous ones and call for further investigation and ongoing monitoring of SARS-CoV-2 mutations.
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The first of the investigations, published in The Lancet Infectious Diseases, has sequenced the complete genome of the virus in 341 patients admitted to two hospitals in the United Kingdom between November 9 and December 20, 2020. And has compared the evolution of the disease between those affected by the British variant and those who do not. (58% and 42% respectively): 36% of the former and 38% of the latter became seriously ill, which led them to rule out an “association” between B.1.1.7 and “increased The severity of the disease”. They were also not more likely to die. According to the data review, 16% of those affected by B.1.1.7 died within 28 days of detection, and 17% of those associated with another strain.
What the researchers did find is that more patients in the first group had to be administered oxygen through a mask or nasal cannula, but they point out that “it is not a clear measure of the severity of the disease” because they may have received it “for reasons not related to COVID-19 or as a result of underlying conditions. ” To get closer to the transmitting potential of B.1.1.7, the authors reviewed the data generated by the PCR to know the amount of virus in the nose or throat of each person. And this indicated that the samples of the British variant “tended to contain higher amounts of virus”, something “consistent” with the evidence that people affected by this lineage are more contagious than those of the first one detected in Wuhan, say the authors .
As usual, the researchers acknowledge some limitations of the study, but stand out as a “strength” that was carried out at the same time that the variant was emerging and spreading in the United Kingdom, that is, before the saturation of the health system: The peak of hospital admissions and health service stresses provided us with a crucial time window to gain vital insights into how patients differ in severity or death, “says Eleni Nastouli, researcher at University College London Hospitals NHS Foundation Trust and co-author of study. The doctor stresses that “it is the first study in the UK” that uses whole genome sequencing data.
R rate increase
Similar conclusions brings a second, published in The Lancet Public Health, which has examined data from 36,920 users of the UK COVID Symptom Study app who tested positive for COVID-19 between September 28 and December 27, 2020. And combined it with the results of genomic surveillance from the virus in the country. For each region (Scotland, Wales and the seven of the health system in England) and symptom self-reported by users through the app, the researchers analyzed the association between the proportion of the British variant in each place and that of people who declared the symptom during the study period.
The analysis, the researchers emphasize, “did not reveal statistically significant associations” that B.1.1.7 alters the type of symptoms or the total number of them. Neither is the proportion of people who experienced prolonged COVID-19, which they define as “symptoms that persist beyond 28 days without an interruption of more than a week.” The study found no evidence that the variant affected reinfection, except in Scotland, but the researchers note that less data was available and reinfections “correlated more with the overall regional increase in cases” than with a rise in B. 1.1.7.
They did find that the British variant increased the so-called basic reproductive number or R number, which measures the average number of people who become infected through a case, “by 1.35 times compared to the original strain.” An estimate that is similar to that of other studies investigating the transmissibility of the variant. But, in addition, the work concludes that despite the rise, the R rate was below 1 – it is understood that the epidemic is decreasing – “during local and national closures”, which “indicates a decrease in transmission” even in those regions with more preponderance of the British variant.
Claire Steves, honorary consultant at King’s College London and co-director of the study, points out that the conclusions “confirm the increase in transmissibility but also show that B.1.1.7 clearly responded to the restrictions and does not seem to escape the immunity obtained. from exposure to the original virus. ” “It is likely” that current vaccines and public health measures “will continue to be effective against it,” adds Mark Graham, also a doctor at King’s College London.
Researchers who did not participate in the study highlight “the consensus” that the variant is more easily transmissible, but also the different conclusions that, on the contrary, the work shows regarding the evolution of the disease. A group of scientists from the National Center for Infectious Diseases of Singapore points to the same on the first of the studies and who did not participate in its elaboration. The researchers highlight “important advantages” of the latter over others that associated the British variant with greater severity and death, but the finding, they emphasize, “requires further confirmation in larger studies. ”