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As new coronavirus strains emerge and infect more people, questions loom over vaccine effectiveness.
SARS-CoV-2, the virus that causes COVID-19, keeps changing, generating new and more transmissible versions as the world scrambles to stay ahead of a pandemic that has killed more than 2.3 million people so far.
First, a variant was detected in the United Kingdom, causing an explosion of new cases, then two more emerged in South Africa and Brazil, raising questions over whether vaccines would be effective against these mutations.
Here is what you need to know:
UK variant
The first variant was first detected with 23 mutations in September last year in the UK. The B.1.1.7 is believed to be about 50 percent more contagious than SARS-CoV-2, according to the British government, and it accounts for more than 60 percent of positive tests in the UK.
While the variant is believed to spread faster, scientists say there is a “realistic possibility” that new infections are also “associated with an increased risk of death” compared with infections from SARS-CoV-2.
Since then the UK mutation has spread to at least 75 countries.
Brazil variant
This variant was first detected in early January in Japanese travellers who passed through the Brazilian Amazon region. It is widely believed this strain caused an explosion of cases in Manaus, the province’s capital, causing a dire oxygen shortage.
Relatives of patients hospitalised or receiving care at home buy oxygen and fill cylinders at a private company in Manaus, Brazil [File: Bruno Kelly/Reuters]
Infections surged by 125 percent in Manaus between January 7 and 22, according to the National Council of Health Secretaries. The new variant is now spreading across the country.
South Africa variant
The B.1.351 variant first emerged in December 2020 in South Africa’s Eastern Cape Province. It has now been found in 32 countries, including Mozambique, Kenya and Botswana.
Like the strain detected in the UK, it is believed to be more contagious. The variant – also known as 501.V2 – includes the E484K mutation, which could explain why some vaccines have so far been found less effective against it.
South Africa suspended the use of the Oxford/AstraZeneca coronavirus vaccine for now and is speeding up the roll-out of other vaccines.
Do vaccines work on the variants?
The more a virus mutates, the less effective a vaccine becomes. In the worst-case scenario, the virus replicates to such an extent the vaccine is not adequate to help the body produce the right protection.
The Moderna and Pfizer/BioNTech drug companies, whose jabs received emergency approval in the US, said on January 25 their vaccines, while still effective, offer less protection against the B.1.351 variant than they did against other strains in the UK.
On Saturday, a non-peer-reviewed study reportedly showed that AstraZeneca/Oxford jab appeared to offer only limited protection against mild disease caused by the South African variant.
Last week, results showed that the Johnson & Johnson one-shot vaccine’s level of protection dropped from about 66 percent to 57 percent for mild and moderate cases when tested in South Africa. Meanwhile, the Novavax jab, which is 89-percent effective in trials in the UK, showed 60 percent efficacy in the African country.
The good news is that some vaccines, such as those by Pfizer/BioNTech and Moderna, use mRNA technology, which allows for reconfiguring a vaccine to transmit different genetic instructions more easily.
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