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What you should know about Covid-19 variants

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These variants are of concern because they have increased reproductive (replication) and adaptability success (fitness) and are able to be transmitted very fast.

Mutations such as the South African variant have shown that the rate of neutralisation by the antibodies of the previous virus is low or close to nil. This may also mean low vaccine efficacy by the current vaccines.

If these variants outweigh the existing virus strains, it means we may have a trigger of new infections, even in the populations already infected, altogether.

What about Covid variants present in Kenya and East Africa and their implications on already developed vaccines?

So far, Kenya and most East African countries have no recorded data to suggest which of the four variants of concern are becoming dominant, their prevalence or their role in the nations’ surge, with the exception of A.23.1, a variant that originally emerged from Uganda and Rwanda last year and is now dominant in the two countries.

This particular variant is not of concern but of interest as it has a mutation in a particular position of the spike gene that might make it more transmissible than the original virus variant.

Even with the presence of the Delta variant in Kenya, there exists no data that indicates the percentage of infections each variant is responsible for as Kenya, like many other African countries, is only sequencing viral genomes at a rate of less than 1 per cent of administered Covid testing.

The lack of data on the four variants of concern must be taken with caution since the countries have not invested in molecular surveillance to determine the true picture of the variants in these countries.

All the vaccines currently in use — Pfizer, Moderna and AstraZeneca — were generated targeting the wild type strain (Wuhan/China strain) and the US D614G strain, with the exception of the Johnson & Johnson vaccine (which was developed to deal with the B.1.1.7, B1351 and P1 variants).

What it means is that for instance, in Kenya, AstraZeneca would be effective against the two mentioned strains, and studies have shown that it has reduced efficacy against the emerging strains: B.1.617.2.

However, some of the vaccine manufacturing companies are targeting variants in the development of booster vaccines.

Moderna has developed a vaccine against the South African variant, which is now ready for clinical trials. Johnson & Johnson is also working on a particular version of its one-shot vaccine that targets the spike protein of the South African variant. Pfizer-BioNTech is also working on a third dose for those who have already received the two required doses as an additional approach to dealing with the emerging variants.

Novavax has already crafted strain-specific versions of its original vaccine and is testing them on monkeys.

With human clinical trials expected to begin in the middle of this year, which will not only include variant-specific vaccines but also a multivalent one designed to protect against all known strains of the virus that causes Covid-19.

Can the mutations in the Sars-Cov-2 result in a completely different disease?

No, mutations may not lead to entirely new diseases. It may, however, change the severity, rate of transmission or presentation symptoms of the disease.

For instance, the B.1.1.7 variant is estimated to be up to 70 per cent more transmissible.

So far, the mutations in the three strains of concern have not shown an increased rate in disease severity, with the exception of B.1.617.2 (first identified in India).

However, some studies have shown that mutations (deletion specifically) in a variant known as the Δ382 variant has reported reduced severity in infection and the inflammatory response.



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