Delta strain: What is known about the covid-19 variant that concerns vaccine manufacturers?

The variant of the coronavirus dubbed the ‘Delta’ strain and first registered in India in October last year, is spreading rapidly in several countries and is already dominant in some regions.

On May 11, the WHO classified the Delta strain as a «variant of concern» and announced this Wednesday that it has already been detected in more than 80 countries, details a study by RT.

England’s Public Health authorities announced last week that Delta is 64% more contagious than the Alpha strain, initially detected in the UK.

From the WHO they pointed out that the variant can cause more serious symptoms than other strains, highlighting that additional studies are necessary to confirm the data in this regard.

Tim Spector, professor of Genetic Epidemiology at King’s College London and leader of a study in which data on covid-19 symptoms was collected through an application, said last week that the Delta feels like «a bad cold». 

Symptoms of the Delta strain

Among the symptoms associated with the strain are:

– headache

– throat pain

– runny nose

– fever

– stomach ache

– loss of appetite

– vomit

– nausea

– joint pain

– hearing loss

The deputy director for clinical-analytical work of the Central Scientific and Research Institute of Epidemiology of Rospotrebnadzor [Russian health agency], Natalia Pshenichnaya, pointed out, (referring to Indian doctors), that diarrhea and microthrombosis are also detected in the lower extremities that can cause gangrene and amputation of fingers.

A study, published this Monday in The Lancet magazine, indicated that the risk of hospitalization increases almost twice in patients with the Delta variant, compared to the Alpha variant.

Dominant in various regions

The Delta is already the majority variant in the UK, according to the executive director of the British Health Security Agency, Jenny Harries. Official data released this Friday indicate that the strain now accounts for 99% of all infections in the country.

In Germany, Lothar Wieler, director of the Robert Koch Institute said on Friday that the variant now accounts for about 6% of all infections, but this number is growing. «It is not a question of whether Delta will become [the variant] dominant, but the question is when», said Wieler, predicting that the strain will dominate Germany in the autumn.

Portugal is currently suffering an increase in daily cases of coronavirus that has not been registered since February, and in these conditions the country’s authorities announced this Thursday that entry or exit from the Lisbon metropolitan area will be prohibited in the coming weekends. AP cites experts who pointed to local transmission of the Delta variant.

Meanwhile, the mayor of Moscow, Sergei Sobianin, announced this Thursday that the city is close to «temporary, but strict» restrictions due to the rapid growth of new cases of coronavirus and the next day detailed that the Delta variant was registered at 89 % of people currently infected with coronavirus in the capital. He stressed that the strain is «more aggressive» and spreads more quickly, adding that a person needs a number of antibodies almost twice as high to be able to cope with it, compared to the usual variant detected since the beginning of the pandemic in the country.

Are vaccines effective against this strain?

Data from British health authorities suggest that current vaccines are less effective against the Delta strain compared to Alpha. According to Scotland’s Public Health authorities, the Pfizer / BioNTech vaccine is more effective than the Oxford / AstraZeneca vaccine.

And England’s Public Health authorities indicated that the Pfizer / BioNTech vaccine is 96% effective against hospitalization in case of infection with the Delta strain, while the effectiveness of the Oxford / AstraZeneca drug is 92%.

At the same time, several experts emphasize that the level of protection against the strain after a dose of the vaccine is low.

Alexander Guíntsburg, director of the Gamaleya National Research Center for Epidemiology and Microbiology in Moscow, responsible for the creation of the Sputnik V vaccine, stated that the drug is effective against the strain.