Amanda Parsons, a registered nurse on staff at the Northwood Care facility, prepares a dose of the Moderna vaccine to Halifax on Jan. 11, 2021. THE CANADIAN PRESS/Andrew Vaughan

Scientists say it’s normal for viruses to acquire small changes or mutations in their genetic alphabet as they reproduce.

In March, just a couple of months after the novel coronavirus was discovered in China, a mutation called D614G emerged that made it more likely to spread. It soon became the dominant version in the world.

Now, after months of relative calm, “we’ve started to see some striking evolution” of the virus, biologist Trevor Bedford of the Fred Hutchinson Cancer Research Center in Seattle wrote on Twitter recently.

“The fact that we’ve observed three variants of concern emerge since September suggests that there are likely more to come.”

The coronavirus is becoming more genetically diverse, and health officials say the high rate of new cases is the main reason. Each new infection gives the virus a chance to mutate as it makes copies of itself, threatening to undo the progress made so far to control the pandemic.

Here's a look at three known variants of the novel coronavirus that causes COVID-19:

B.1.1.7

The U.S. Centers for Disease Control says this variant is believed to have first emerged in the United Kingdom in September.

It has now been reported in at least 30 countries, including Canada, where it was first found in Ontario on Boxing Day.

It spreads much more easily, says the CDC.While early reports found no evidence to suggest that the variant has any effect on the severity of disease or vaccine efficacy, scientists in the U.K. say evidence shows that it may be associated with an increased risk of death compared with other variants.

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B.1.351

The CDC website notes that this variant was first identified in Nelson Mandela Bay, South Africa, in samples dating back to the beginning of October.

It was identified in Zambia in late December, at which time it appeared to be the predominant variant in that country. It was first found in Canada in Alberta on Jan. 8.

There is no evidence to suggest, right now, that this variant has any effect on disease severity.

But some lab tests suggest the variant may be less susceptible to antibody drugs or convalescent plasma -- antibody-rich blood from COVID-19 survivors -- both of which help people fight off the virus.

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P.1

This variant was first reported by the National Institute of Infectious Diseases in Japan in four travellers from Brazil and found in the United States at the end of January, says the CDC.

While yet to be reported in Canada, Prime Minister Justin Trudeau has called it concerning.

The CDC says it is more transmissible and can potentially reinfect people.

Like the variant from South Africa, there is some suggestion that the Brazil variant is less susceptible to treatment.

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-- With files from The Associated Press.

This report by The Canadian Press was first published Feb. 4, 2021

News from © The Canadian Press, 2021