Estimated half of new Covid infections the B117 variant, Dutch gov't says

Of all the new coronavirus infections in the Netherlands, an estimated 50 percent are caused by the B117 variant first identified in the United Kingdom, the cabinet said in a letter to parliament, NOS reports.

The B117 coronavirus seems to be more contagious, so it was expected that it would quickly spread through the Netherlands and become the dominant strain in the country. Last week the RIVM said that about a third of infections could be traced back to this strain of the cronavirus.

According to the government, the reproduction number (R-number) of the B117 strain is estimated to be 49 percent higher than that of the original strain. In mid-January, the original strain's reproduction number was 0.85, which meant that each person infected with this strain passed it on to 0.85 other people. At that time, the B117 variant's R-number was 1.27. For the virus to be on decline, the R-number must be below one. 

That lead to the estimate that half of all infections that started showing symptoms on January 26 were caused by the B117 variant.