The highly transmissible Covid-19 variant, which first emerged in India, is spreading rapidly around the world, health authorities say, intensifying the race to increase global vaccinations.
The B.1.617.2 variant, now dubbed the Delta variant, is in at least 60 countries, including the United States and the United Kingdom, and British researchers recently estimated that it was possibly 40-50% more transmissible than B.1.1. 7-variant or Alpha, which in turn is more transmissible than the original virus and quickly spread across the globe.
“Given this level of transferability, I would expect it to actually spread worldwide,” Sharon Peacock, CEO and chairman of the Covid-19 Genomics UK Consortium, told The Wall Street Journal̵
In the UK, the Delta variant is rapidly displacing the Alpha variant, and health officials believe it is contributing to an increase in Covid-19 cases and hospitalizations in the country, even if it starts from a low baseline. Previously, approx. 98% of cases in the UK are the Alpha variant, but the Delta variant has started to take over after being introduced in the country in March and now accounts for approx. 75% of cases, said Dr. Peacock. Covid-19 Genomics UK is a consortium of public health and academic organizations that collects, sequences and analyzes genomes from Covid-19 tests in the UK to manage pandemic response efforts.
“We are seeing a big shift in the cause of infection in the UK and this change has happened relatively quickly over a period of a few weeks and it does not look like it will really stop,” said Dr. Peacock, who is also Professor of Public Health and Microbiology at the University of Cambridge.
The variant will also become dominant in the Democratic Republic of Congo, said John Nkengasong, director of the Africa Centers for Disease Control and Prevention, at the WSJ conference. Dr. Nkengasong said the risk from the variant is significant and that the continued emergence of new variants speaks to the need to strengthen genomic sequencing across the globe.
Anthony Fauci, the United States’ leading infectious disease doctor, said on Tuesday that the Delta variant currently accounts for more than 6% of sequenced Covid-19 cases in the United States. The Alpha variant is still dominant in the country.
“We can not let that happen in the United States,” he said. Fauci on the situation in the UK during a media briefing in the White House. He urged people to get vaccinated if they have not already been, and make sure they get their second dose.
The variant may also be associated with an increased risk of serious illness and hospitalization, say health authorities, but that connection is less certain.
The currently available vaccines work against the Delta variant, early data suggest, but they appear to be somewhat less effective, especially after just one dose. According to data from Public Health England, both the AstraZeneca and Pfizer BioNTech vaccines were approx. 33% effective against symptomatic Covid-19 caused by the Delta variant after a dose compared to being approx. 50% effective against the Alpha variant.
However, after two doses, the Pfizer vaccine efficacy against the Delta variant increased to 88% and the AstraZeneca vaccine was approx. 60% effective.
Both Dr. Peacock and Nkengasong expressed concern that if the virus is allowed to continue to spread, new variants could emerge in the next few months, against which current vaccines may be even less effective.
“I think it’s a step in a series of step-by-step steps, or potentially there could be a big step towards a variant that is more resistant to vaccination,” said Dr. Peacock. “The way we get on top of the emergence of variants is to stop transmission and vaccinate the world.”
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