In the Chinese province of Guangdong, authorities are rushing to quash an outbreak of a worrying Covid-19 variant before it can spread. Officials are instituting lockdowns, compulsory testing campaigns, flight cancellations, and other serious measures.
What has the Chinese officials so concerned is that the outbreak appears to be tied to a Covid-19 variant known as the Delta variant, formerly referred to as the Indian variant. That’s the variety that is thought to have played a key part in the explosive outbreak in India in April and May, and it has the world on edge.
Scientific understanding continues to develop, but early information suggests that while fully vaccinated people are well protected, it poses a serious threat to unvaccinated and partially vaccinated people and populations.
“The most vulnerable individuals to variant B. 1.617.2 are those that have not been fully vaccinated, which accounts for a significant proportion of the global population, especially in Latin America, Asia and Africa,”
analyst David Mackie wrote in a Monday research note.
First identified in India in October, the variant became a pressing worry in recent months. The World Health Organization designated it a variant of interest in April, and named it a variant of concern on May 11.
According to a risk assessment published June 3 by Public Health England, a U.K. agency, the variant appears to be more transmissible than the original version of the virus that causes Covid-19. It is now the dominant variant in the U.K.
The risk assessment also suggests that there may be a higher risk of hospitalization in cases caused by the Delta variant, though that conclusion is less robust.
Public Health England says that a single dose of a two-dose vaccine offers significantly less protection against the Delta variant than it does against other versions of the virus. Two vaccine doses offers far more protection.
A paper published by Public Health England, which hasn’t yet been peer reviewed, found that vaccine effectiveness against the Delta variant after a single dose of the
(ticker: AZN) or the
(PFE) vaccines was 33.5%, compared with 51.1% for the so-called U.K. variant. After two doses, the difference was far less dramatic. The
vaccine was 87.9% effective against the Delta variant after two doses, compared with 93.4% effective against the U.K. variant, according to the Public Health England paper.
A paper published in The Lancet on June 3, based on a laboratory study, found that the Delta variant elicited lower antibody levels in people vaccinated with the Pfizer vaccine than other variants did.
The CDC has named the Delta variant a variant of interest, though it hasn’t upgraded it to the category of variant of concern. The WHO, however, calls Delta one of four variants of concern globally.
In his Monday note, J.P. Morgan’s Mackie says that the variant has potential to spread quickly through unvaccinated populations. “Our reading of the evidence suggests that variant B. 1.617.2 is much more transmissible than either the original SARS-CoV-2 strain or variant B.1.1.7, but fully vaccinated individuals are well protected,” he wrote. “This means that infections will spread very rapidly through a susceptible population, as has happened in India in recent months.”
Developed countries, Mackie says, seem largely safe. In emerging markets, however, the picture is far more worrying. “India’s experience in recent months illustrates what can happen when SARS-CoV-2 variant B. 1.617.2 runs through a susceptible population,” he writes. “This argues strongly not only for faster vaccine production but also a more equal distribution. Of the 2.1 billion doses of vaccine administered thus far, 30% has gone to [developed market] countries, even though they account for only 12% of the world’s population.”
Write to Josh Nathan-Kazis at [email protected]