Covid-19 impact of new strains

At least three major coronavirus variants have been discovered abroad and made their way to the U.S[1]. The strains are:

The UK strain
The South African strain
The Brazilean strain

All three have been detected in the US.

Scientists have learned that the virus has changed in ways that increase its ability to spread and may cause more severe disease.

"The U.K. strain, called B.1.1.7, was first reported in the U.S. in late December, and it spreads more quickly and easily than other variants, according to the Centers for Disease Control and Prevention. Dr. Anthony Fauci, the nation's leading infectious disease physician said on TODAY Thursday that it could become the dominant strain in the U.S. by the end of March. As of Feb. 23, there were 1,881 reported cases of this variant in 45 U.S. states. It's also spreading at high levels in Denmark and Scandinavia".[1]

"The modeled trajectory of this variant in the U.S. exhibits rapid growth in early 2021, becoming the predominant variant in March,” according to the CDC study released Friday Jan 15 [2]

Are the new strains more deadly?

Worldwide view

There is some evidence (see below) of an increase in the ratio of deaths/confirmed cases for Denmark, South Africa, the UK and the US.starting December and January.

Ratio of deaths to confirmed cases since May 2020	Detail ratio of deaths to confirmed cases November 1st 2020 forward

For the above-mentioned countries, looking at the dates when the ratio was last at a minimum and the following first maximum, we get the table below:

Country	minimum date (ratio)	maximum following minimum (ratio)	days between minimum and maximum	Increase in ratio
Denmark (DK)	12/21/2000 (0.76)	2/12/2021 (1.12)	53 days	47%
United Kingdom (UK)	1/17/2021 (2.61)	3/3/2021 (2.95)	45 days	13%
United States (US)	1/20/2021 (1.68)	3/6/2021 (1.81)	45 days	7.7%
South Africa (ZA)	12/27/2021 (2.66)	3/10/2021 (3.35)	73 days	25%

This increase of the ratio for the UK variant in Denmark, the UK and the US is in line with the March 10 reported increased virulence of the new strain [4].

Confirmed cases and deaths since Jan 2020	Confirmed cases and deaths since November 1st 2020

It is also seen that there has been an uptick in confirmed cases for Brazil, Finland, Norway and Sweden in February 2021.

US States view

As of Jan 29, 2021 there were 315 cases of the UK strain detected in the US The leading states with 14 or more cases were CA (92 cases), FL (92), NY (22), Michigan (17) and GE (14). and as of Feb. 23, there were 1,881 reported cases of this (UK) variant in 45 U.S. states. [3].

As seen below there is a slight increase in. the ratio deaths/confirmed. However, it is unclear whether this is related to the virus change, since unlike the countries above, there are similar large changes earlier in 2020 which would have had nothing to do with the UK variant.