Remind me about the Delta variant...

The Delta variant was previously called the ‘double mutant’ or ‘Indian’ variant, and is dubbed a ‘variant of concern’—which means there is evidence it is more infectious and/or causes more severe disease and/or renders certain Covid treatments ineffective. This B.1.617.2 variant has key mutations on the virus’ spike protein (explained in detail here). And here’s why everyone is worried about it:

One: It is far more infectious than any other variant. It is at least 40% more transmissible than the Alpha (UK) variant—which itself is 50% more transmissible than the original version of the virus. This news report on a Delta variant scare is perhaps the best illustration of how scarily fast-spreading this virus is:

 Two: Another key mutation makes it easier for the virus to invade body cells and spread. More importantly, it can also make certain Covid treatments like monoclonal (artificial) antibody cocktails ineffective.

Three: It is somewhat resistant to vaccines—and a single dose offers very little protection against this variant. A UK study found that one dose of either the Pfizer or AstraZeneca (Covishield) vaccine offered only 33% protection against Delta compared to 50% against Alpha. Two doses, however, boosted AstraZeneca’s efficacy to 60% and Pfizer’s to 88%. The good news: Even those who have received just one dose of a vaccine are 75% less likely to be hospitalised. So vaccines at least protect against severe disease.

Four: And that’s important because a Scottish study showed that people infected by the Delta variant were roughly twice as likely to be hospitalized than were those infected with Alpha.

And Delta is the most common variant now?

It has been reported thus far in 80 countries and is the most common variant in India and the UK.

Europe: In the UK, 99% of sequenced and genotyped confirmed coronavirus cases across the country are the Delta variant. In just one week, the number of Delta variant cases jumped by 33,630. And that’s despite the fact that 59.5% of the adult population has been fully vaccinated—and 81.6% have received at least one dose. So it has all of Europe very worried—even though the numbers are still low on the continent. 

The United States: In the US, leading Covid expert Dr Fauci has called it “the greatest threat”—and it is spreading quickly. In early April, Delta represented just 0.1% of cases, but that number jumped to 9.5% by June. As of a few days ago, the estimate hit 20.6%. But Alpha was responsible for anywhere from 38 to 86% of all new U.S. cases last month. Experts agree, however, that Delta will likely become the most dominant strain soon, and spread like wildfire in parts of the country where vaccine hesitancy is the highest—creating “two Covid nations.”

Africa: is at the highest risk since most nations have vaccinated less than 5% of their populations:

“Surveillance in African countries is extremely limited, but there are hints that the variant is already causing cases there to surge. Several sequences of the variant have been reported in the Democratic Republic of the Congo, where an outbreak in the capital city of Kinshasa has filled hospitals. The variant has also been detected in Malawi, Uganda and South Africa. Countries that have close economic links to India, such as those in East Africa, are probably at the greatest risk of seeing a surge in cases caused by Delta.”

South America: has remained mostly untouched, including Covid-ravaged countries like Brazil—due to travel restrictions. 

Point to note: Epidemiologists warn that Delta may irrevocably alter the future of the pandemic—triggering new waves across the world:

“This combination of high transmissibility, high severity, and escape from vaccines makes Delta a very, very dangerous variant… It's going to be quite hard to contain, and very likely will become the dominant variant in a matter of weeks. It could change the trajectory of the global pandemic.”

And what’s this new horror called Delta plus?

The scientific term for it is AY.1 or B.1.617.2.1—and is a result of a change in the Delta variant. It contains an added mutation called K417N—which is also found in the Beta (South Africa) variant and the Gamma (Brazil) variant:

“[The mutation] is believed to help the virus dodge neutralising antibodies—a vital part of our immune system’s defences. This means it can make vaccines and antibody drugs less effective, and increase the risk of reinfection, as happened on a large scale in Manaus, Brazil, with the gamma variant.”

According to Indian experts, the three most worrying characteristics are its increased transmissibility, ability to more strongly bind to receptors of lung cells, and reduce the effectiveness of monoclonal antibody treatments.

Point to note: Yesterday, authorities went back-and-forth on whether to classify Delta plus as a ‘variant of concern’—and finally did so on the recommendation of INSACOG, a consortium of 28 laboratories of the Health Ministry that is involved in genome sequencing.

The spread in India: The Delta plus variant has been detected in 22 samples across six districts in the country. Sixteen of them were found in Maharashtra, while the remaining were found in Kerala and Madhya Pradesh. The union government has directed all three states to ramp up surveillance and containment efforts. 

The global spread: The variant has also popped up in 12 other countries—including Nepal, Portugal, Japan, United Kingdom, and the United States. The greatest number of cases were reported in the UK (45), followed by Switzerland (23), and Portugal (21). But this doesn't mean they have the most cases. As The Hindu notes:

“The number of cases reported from a country is not always indicative of the prevalence of the variant and has to do with the extent of genome sequencing of virus samples. The U.K. has sequenced nearly 466,437 samples and reported 45 cases, the U.S. has sequenced 549,164 samples and reported 12 cases, whereas the number of samples India has sequenced is only about 5% (28,065) of these figures.”

Point to note: Delta plus has not been associated with any major outbreak so far. And we will have to wait for analysis and data to figure out whether it is a more worrying iteration of the virus.

The bottomline: The virus and the vaccine are locked in an arms race—and the winner will determine the trajectory of this pandemic. The longer it takes to vaccinate the world, the more likely it is that we will incubate new and more dangerous variants.

Reading list

The Hindu and The Conversation have the best explainers on the Delta plus variant. National Geographic and New York magazine have solid overviews of the original Delta variant. NPR reports on the spread of the Delta variant in Europe, while this Bloomberg News report tracks the rising worries in the US. The Atlantic explains why the impact of the Delta variant will be unpredictable.