COVID-19 mutant variants and herd immunity

Transcript

By now, you’ve likely heard about the new variant strains of COVID-19 that are circulating around the world.

There are a number of concerns with these new strains, as they may make it easier to spread COVID-19 to others, and they may increase the severity of COVID-19 illness.

This video aims to explain what is known about the different strains and how they may affect achievement of herd immunity.

All viruses mutate. As more people get infected with a virus, the virus has more opportunities to multiply and there are more chances that a mutation may occur.

A mutated virus can be considered a new strain when the virus has enough mutations to make it distinct from the original virus.

So, often new strains appear in places with uncontrolled outbreaks.

The new strains can become a problem when the mutation gives the virus an advantage, such as making it easier to quickly spread or increasing the infection severity.

For each of the COVID-19 variant strains, it’s likely the mutations took place within a single patient who was infected with the virus for a long period of time.

Most relevant COVID-19 mutations affect the spike protein, which is a protein located on the outside of the virus that can bind to the host cell, helping the virus enter the cell.

The genetic code for the spike protein is within the “conserved” region, meaning the spike protein tends to be consistent across each new generation of the virus.

Most of the developing vaccines have been targeting proteins on the viruses, one of which is the spike protein, so alterations in the spike protein may make vaccines somewhat less effective.

As of early March 2021, there are three clinically important strains of COVID-19: B.1.1.7, also called the UK strain, B.1.351, also called the South African strain, and P.1, also called the Brazilian strain.

While there are a number of other strains that exist, these three strains are clinically important because they potentially may be more contagious and more virulent than the original COVID-19 strain.

B.1.1.7 was first discovered in the United Kingdom in late 2020 and contains multiple mutations, including those within the spike protein.

By December of 2020, it was reported to be present in numerous countries including the US.

This strain is considered to be one of the most transmissible, and it spreads between people 25 to 40% faster than the other COVID-19 strains.

It’s still unclear why this higher transmission rate occurs, however, continued compliance of social distancing and personal protective equipment need to be taken to reduce the spread of B.1.1.7.

There is some concern that the B.1.1.7 may also have a higher rate of severe COVID-19 symptoms, as well as an increased fatality rate.

However, research supporting these concerns is very new, and more evidence needs to be collected to confirm these concerns are true.

There is also no current evidence that shows B.1.1.7 increases rates of reinfection with COVID-19 due to this strain.

Studies have shown that the current COVID-19 vaccines are still effective against this strain, even with the mutation in the spike protein.

So even though B.1.1.7 is able to spread faster than the original COVID-19 virus, the vaccines currently being distributed should help to slow the spread of this variant strain.

B.1.351 was first identified in South Africa in samples dating back to October 2020.

It’s also been found in samples from other countries, including the US, as of January 2021.

B.1.351 has several of the same mutations that the B.1.1.7 has, however, it has enough unique mutations to be considered its own strain.

Some early research suggests convalescent plasma and the current COVID-19 vaccines may be less effective against this strain.

However, just like the vaccine studies with the B.1.1.7 strain, these are preliminary studies, and more research is needed to confirm these concerns.

That said, the current COVID-19 vaccines still show prevention of severe COVID-19 symptoms and hospitalizations.

P.1. was first found in Brazilian travelers in Japan in late 2020 and continues to be a major strain within Brazil.

In the spring of 2020, the original COVID-19 strain infected 75% of the Brazilian city Manaus.

It was thought by some epidemiologists that the city reached herd immunity given the high-percentage of infections in the spring.

However by December 2020, another wave of COVID-19 infections began, and the new wave was being caused by the P.1 variant strain.