The Delta variant detected in 148 countries: when it emerged, why it is dangerous and whether vaccines work

Widespread transmission of Delta is expected in Ukraine in the autumn.

The Delta coronavirus variant has been registered in at least 148 countries and territories. We explain when this variant of the disease emerged, why it is dangerous and whether vaccines are effective against it.

It is worth noting that the British Alpha variant has been recorded in 190 countries, the Beta variant from South Africa in 138, and the Gamma variant from Brazil in 82.

When and where Delta was discovered

The variant was first detected in India in the autumn of 2020, which is why it was long referred to as the "Indian" variant, until the World Health Organization decided to stop using geographic references in virus names.

The coronavirus variant initially spread across India, and then began to appear in other countries. Delta led to new waves of infections in many countries. The variant is now considered dominant worldwide.

In Ukraine, the incidence of Delta is also rising: as of August 12, 300 cases of infection with the variant had been registered in the country. Widespread transmission of Delta is expected in Ukraine in the autumn, since it now dominates in more than 20 European countries.

How dangerous is the Delta variant

The Indian variant has not yet been studied sufficiently, but according to preliminary estimates, it is 1.6 times more contagious than the Alpha variant, leads to hospitalization 2.26 times more often, and the risk of intensive care upon infection increases 1.45 times.

Symptoms of Delta infection may be classic for coronavirus: cough, high temperature, loss of smell or taste. However, with the new variant such symptoms are becoming less common. For example, loss of smell no longer even makes it into the top 10 most common symptoms.

In some cases, Delta may present as a gastrointestinal disorder. Abdominal pain, vomiting and diarrhea are gradually being added to the known symptoms.

This coronavirus variant progresses more aggressively and quickly than previous variants: on the second or third day after hospitalization, patients' oxygen saturation drops sharply, so they cannot breathe on their own and need intensive care. The age of severely ill patients is 30 to 40 years. The WHO has also recognized Delta as more contagious than other variants.

Are vaccines effective

The effectiveness of vaccines against the Delta coronavirus variant remains a subject of research. There is currently no precise data showing that existing vaccines are ineffective against the variant.

Some studies have shown that two doses of the Pfizer or AstraZeneca vaccine provide high protection against Delta: 88% with full vaccination with Pfizer and 67% with AstraZeneca.

In addition, Pfizer stated that a third booster dose of its coronavirus vaccine increases the number of antibodies in the human body by 11 times, and also strongly protects against the Delta variant.

According to Ukraine's Chief State Sanitary Doctor, high mortality from infection with the Delta coronavirus variant is observed among the unvaccinated.

Igor Kuzin
Chief State Sanitary Doctor of Ukraine

Indeed, a person infected with the Delta variant is much more contagious and has a larger number of viral particles in the upper respiratory tract. At the same time, it (the disease — ed.) does indeed more often lead to hospitalization, that is, it progresses more severely in a person infected with the Delta variant. However, countries provide different information on fatality. The highest mortality rates from Delta infection were mostly observed among the unvaccinated population. In countries where the vast majority of the population was vaccinated, mortality figures did not differ from, for example, those of the Alpha variant.

He noted that the effectiveness of the vaccine against infection with the Delta variant decreases by 10%: "But protection still exists. And now the countries where a Delta outbreak is registered show that the predominant percentages of mortality and predominant percentages of severe course (this is almost 98-99%) are among the unvaccinated population."