Researchers in Japan have estimated that the variable type B.1.1.7 of recent acute coronavirus 2 (SARS-CoV-2) respiratory syndrome that appeared in England is 40% more mobile than series that previously circulated in the country.
The SARS-CoV-2 virus is the agent responsible for the 2019 coronavirus outbreak (COVID-19) which remains a major threat to global public health and has now claimed more than 2.68 million lives all over the world.
The researchers state that the 40% higher B.1.1.7 transmission estimate suggests that the measures put in place to control this snoring need to be strengthened by 40%. , compared with those used to control previously circulating sequences.
To achieve the same control effects, contact rates between people had to be lower than 0.71 of the levels achieved using the previous measures.
Chayada Piantham and Kimihito Ito of Hokkaido University warn that the benefits of other recently emerged transmissions such as those identified in Brazil and South Arica need to be urgently underestimated.
A pre-printed version of the research paper can be found on the medRxiv* server, while the article is under peer review.
Number of series in England from September 1, 2020 to February 19, 2021. The nucleotide series were recovered from GISAID on March 1, 2020.
What is known so far about line B.1.1.7?
Since the COVID-19 revolution first began in Wuhan, China, in late December 2019, the rapid release and evolution of the causative agent SARS-CoV-2 has led to the emergence of new mutually beneficial changes. spread over the original snoring.
In December 2020, Public Health England identified a new collection of viruses belonging to the B.1.1.7 line, which the World Health Organization named “Variant of Concern” because of its easier spread, compared to strains previously circulated in England.
Since the line was first recognized in the country in September 2020, the number of diseases with this new snort has grown rapidly in October and November. By February 2021, the B.1.1.7 viruses accounted for 95% of all SARS-CoV-2 strains circulating in England.
Previous studies assume that the breeding population is stable over time
Several studies have compared the breeding population (R.; number of secondary diseases due to one disease) of the line B.1.1.7 to the type of series previously circulating in England.
One study found that the R. the B.1.1.7 strain number is between 83 and 118% higher than levels of previous types, and another study estimated it to be between 40 and 75% higher.
The methods used in these studies estimated the increase in referrals under the assumption that R. stable over time during the study period.
However, since more movement of the B.1.1.7 line has been identified, strict control measures, including locking, have been applied in England.
“So the stable R. there is skepticism when analyzing the increase in the number of reproductions of B.1.1.7 compared to the increase in previously circulating series, ”said Piantham and Ito.
What did the researchers do?
The team estimated the selective gain of the B.1.1.7 line over previous series using the time course of the proportion of B.1.1.7 viruses identified in England.
Based on Wallinga-Teunis ’method for estimating immediate reproduction numbers, the method allowed the number of reproductions to change during the study period.
The approach was also based on a model by Maynard Smith, which assumes that the selective gain of mutant strain over previously circulating strains is stable over time.
The researchers downloaded nucleotide sequence data on SARS-CoV-2 viruses detected in England from the GISAID (Global Initiative to Share Avian Influenza Data) database on 1st March, 2021.
The team then implemented the new method to estimate the instantaneous reproduction number of B.1.1.7 sequences, compared to the number of previously rotated sequences.
What did they find?
The researchers estimated that the selective gain of the B.1.1.7 sequences over non-B.1.1.7 rays was 0.40, indicating that the reproduction number immediately of line B.1.1.7 40% higher than the previous rows. .
This suggests that the control measures used to maintain the B.1.1.7 line need to be strengthened by 40%, compared to those used to control previous series, said the team.
To achieve the equivalent control effect, contact rates between individuals had to be limited to less than 0.71 of the levels achieved by the previously used measures.
The selective benefit of new varieties in other countries also needs to be assessed
The team says that as the 17thth March 2021, line B.1.1.7 was found in 93 countries.
“The selective advantage of the B.1.1.7 series over previously circulated series in other countries remains our future work,” the researchers said.
In addition, Piantham and Ito point out that the variables identified in Brazil and South Africa also show higher transmission than previous series.
“There is also an urgent need to estimate the selective benefit of these series,” they conclude.
* Important message
medRxiv publish preliminary scientific reports that are not peer-reviewed and, therefore, should not be seen as final, guiding health-related clinical practice / behavior, or be treated as information established.