What Is the Coronavirus Delta Variant? Everything You Want to Know

What is the Delta variant? Where did it originate?

B1617.2, also known as the highly transmissible SARS-CoV-2 Delta variant, was first identified in December 2020 in India. It is now dominant in both India and the United Kingdom.

SARS- CoV-2 is an RNA virus. Mutation is a natural process as the virus multiplies. Since the outbreak began, thousands of mutations have been seen in SARS-CoV-2. The vast majority of these mutations have no effect. For example, more than 4000 mutations have been identified in the SARS-CoV-2 spike protein to date.

Mutation is a change in a DNA or RNA sequence that can have mild or severe consequences. Mutations in DNA are permanent, whereas mutations in RNA may be temporary because of its fragile structure.

NOTE: Variant means mutations that do not change the overall identity of the virus. Strain means mutations that give the virus another identity. In other words, if this happens, everything starts over. Not every nucleotide change in a virus means it becomes different. Although the form resulting from genetic changes in SARS-CoV-2, called B1617.2, is described by some as both a variant and a strain, we use variant throughout the rest of this article.

Is the Delta variant more transmissible?

By June 2021, the Delta variant had reached 74 countries. The fact that 6 months have passed since its discovery and it has spread to so many countries indicates that the virus is spreading rapidly.

The UK Alpha variant (B.1.1.7 – the variant that caused an increase in case numbers last autumn) had already been left behind. This variant was thought to be 43-90% more transmissible than other variants. Experts believe the Delta variant is 30-100% more transmissible than the Alpha variant. While some researchers suggest it is 60% more transmissible than Alpha, UK Health Secretary Matt Honcock said this rate could be 40%. Honcock also stated that the new variant was thought to be responsible for 91% of cases in England. However, this figure is also thought potentially to reach 96%.

Since 2 June, the number of confirmed Delta variant cases in the United Kingdom has risen from 29,892 to 42,323. Depending on the region, the Delta variant shows a daily increase of 4.5 to 11.5 times.

The Covid-19 Delta variant in other countries and in Turkey

German public health officials said they believed the Delta variant could take hold in Germany by autumn at the latest. Lothar Wieler, president of the Robert Koch Institute for Infectious Diseases, said, “The question is not whether the Delta variant will become dominant in Germany, but when.”

Although Israel had left the decision about vaccinating children to parents, on 21 June it recommended that children aged 12 – 15 also be vaccinated against the Delta virus.

In the United States, the Delta variant is increasing particularly in the Midwest and Southeast. This has been declared a concern by the US Centers for Disease Control and Prevention. Genotyping studies showed that Alpha accounted for 70% in the United States at the end of April and that this fell to 42% in mid-June, while the Delta variant increased. Jeremy Kamil, a virologist at Louisiana State University Health, said that Delta would eventually become dominant in the United States, but vaccination could blunt this somewhat.

Scientists also say Delta poses a major risk in countries with limited access to vaccines or where effective vaccination has not yet been achieved, particularly African countries where less than 5% of the population has been vaccinated. Tom Wenseleers, a biologist and biostatistician at the Catholic University of Leuven in Belgium, said, “Vaccines will never arrive in time, and that will make new variants like these very devastating.”

The Delta variant has been reported in the Democratic Republic of the Congo, and the new coronavirus variant has also been detected in Malawi, Uganda and South Africa.

According to a statement by the Republic of Turkey’s Minister of Health, Dr. Fahrettin Koca, the Delta variant has so far been seen in 134 people in Turkey. 

Why does the Delta variant spread faster?

Changes in the Delta variant’s protein are thought to make it easier to enter human cells. Another study suggested that the mutation in Delta leads the virus to adapt better after binding to human cells. It can thus interact easily with our cells, reach more cells and overcome our immune system.

The Covid-19 Delta variant affects young people more

Research in the United Kingdom shows that young people and adults under the age of 50 are 2.5 times more likely to become infected. Interestingly, a doctor from China says that people with the Delta variant are patients who were treated at the beginning of the pandemic.

The Delta variant causes more severe symptoms

People diagnosed with coronavirus who carry the Delta variant may have a greater likelihood of hospitalization. Studies show that, compared with the Alpha variant, the hospitalization risk for people carrying this variant is nearly twice as high.

An application tracking symptoms in the United Kingdom reported the following as the most important symptoms associated with the new variant:

Delta variant symptoms

• Headache
• Sore throat
• Nosebleed
• Fever

While cough has become a less common symptom, loss of smell is not among the top 10 symptoms.

Researchers are therefore seriously concerned that people will mistake the Delta variant for a bad cold and be unwilling to quarantine, potentially spreading the variant.

Does the BioNTech vaccine protect against the Delta variant?

Experts continue to emphasize the importance of receiving two doses of a coronavirus vaccine against Delta, which is thought to be highly transmissible.

• Related topic: Frequently asked questions and answers about COVID-19 vaccines

BioNTech vaccine reports suggest that two doses protect against the Delta variant by 79% and, in the event of infection, are 88% effective against symptoms.

Another study conducted in the United Kingdom found that one vaccine dose provided approximately 33% protection. The same study showed that this protection was 88% for two doses.

AstraZeneca vaccine reports indicate that two doses were 92% effective against hospitalization with Delta and that there were no deaths among vaccinated people.

Connor Bamfor, a virologist at Queen’s University Belfast, said that this variant could overcome the first vaccine dose, so as many people as possible should receive two doses, and shortening the interval between the first and second doses should even be considered.

Emma Wall, an infectious diseases specialist at the Francis Crick Institute in London, said, “This virus will probably remain active for some time, so we need to stay proactive and vigilant. The most important thing is to ensure that vaccine protection remains high enough to keep as many people as possible out of hospital, and our results show that the best way to do this is to give second doses quickly.” Wall’s research team analyzed antibodies within 3 months of vaccination in people aged 33-52 who had received their first dose of the BioNTech Covid-19 vaccine. The study compared concentrations of neutralizing antibodies against five variants. The results were as follows: people who received two doses of BioNTech had 2.6 times lower antibodies against Alpha and 6 times lower antibodies against Delta. Antibody numbers were much lower in people who had received only one dose. The team plans to continue the same study with AstraZeneca.

BioNTech’s Chairman of the Board Uğur Şahin said that current data on new coronavirus variants, including Delta, were being monitored and vaccine efficacy continuously analyzed in order to be prepared to update vaccines or provide a third dose if needed. Şahin said, “I assume that a third vaccine dose could have high value in renewing immunity. However, we do not yet know when or how often booster vaccination will be necessary.” 

BioNTech, which plans to produce 3 billion vaccine doses together with Pfizer this year, said it plans to produce half of the vaccines itself. 

In his statement about BioNTech’s efficacy against Delta, Şahin emphasized that the variant emerged during a period of waning immunity after vaccination.

The studies did not include two doses of Moderna or a single dose of Johnson&Johnson vaccine.

In conclusion, as countries try to protect themselves against Delta or get through this variant, researchers say that even greater threats need attention. Mads Albertsen, a bioinformatician at Aalborg University in Denmark, says, "What most people worry about is the variants that come next – will we see variants that can truly challenge the vaccines?"

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