Delta variant: What Dr Anthony Fauci and WHO said, global incidence of strain and vaccines' effectiveness

The Delta variant of COVID-19 found in India is the “greatest threat” to the United States’ efforts to fight the pandemic, top scientist and infectious disease expert Dr Anthony Fauci said.

His statement comes at a time that India has reported around 40 cases of the Delta Plus variant, classified as a variant of concern (VOC), in Maharashtra, Kerala and Madhya Pradesh.

What have experts said about Delta variant

Fauci said the Delta variant is more easily transmitted than the original COVID-19 variant, adding that it is associated with increased disease severity.

The highly contagious delta variant is the fastest and fittest coronavirus strain yet, and it will “pick off” the most vulnerable people, especially in places with low COVID-19 vaccination rates, World Health Organisation officials warned Monday.

"As of a couple of days ago, 20.6 percent of the isolates are Delta," Fauci said, referring to the two weeks leading up to 19 June. This number has roughly doubled every two weeks, he added.

Delta, first identified in India, has the potential “to be more lethal because it’s more efficient in the way it transmits between humans and it will eventually find those vulnerable individuals who will become severely ill, have to be hospitaliSed and potentially die,” Dr Mike Ryan, executive director of the WHO’s health emergencies program, said during a news conference.

The agency declared delta a “variant of concern” last month. Studies suggest it is around 60 percent more transmissible than the Alpha strain.

Delta variant in India

The Delta variant was first found in India, known as lineage B.1.617.2, is a variant of lineage B.1.617 of SARS-CoV-2. The World Health Organisation (WHO) named it the Delta variant on 31 May. The second wave it is believed to have driven in April and May saw daily cases crossing the 4 lakh-mark, with crematoriums running out of space, and hospitals facing severe shortage of beds, oxygen and drugs.

Delta variant is found in 80 countries around the world, including India, and it is a variant of concern,” Union health secretary Rajesh Bhushan said at the briefing.

Global incidence of Delta variant

WHO chief scientist Soumya Swaminathan said last week that the variant is becoming the dominant variant globally because of its significantly increased transmissibility. It now makes up at least 10 percent of all new cases in the United States, according to the Centers for Disease Control and Prevention, and is on its way to becoming the dominant variant in the nation.

The United Kingdom recently saw delta become the dominant strain there, surpassing its native Alpha variant, which was first detected in the country last fall. The delta variant now makes up more than 60 percent of new cases in the UK, pushing Prime Minister Boris Johnson to warn the people of a “rough winter ahead”.

According to the Gavi Vaccine Alliance, the Delta variant is making patients become sicker and their condition deteriorate faster than in cases of infections caused by previous variants.

In France and Italy, the prevalence of the variant is still below 5 percent, according to official figures, but has at least doubled in recent weeks.

Vaccines against Delta variant

Fauci said vaccines authorised in the US, including the Pfizer/BioNTech jab, are effective against the Delta variant, even as the White House announced it may not be able to meet its 4 July target of inoculating 70 percent adults.

The Indian government has said Covishield and Covaxin are effective against the Delta variant but data on how effective they are against the Delta Plus will be shared later. Dr Scott Gottlieb, the former commissioner of the Food and Drug Administration (FDA) was quoted saying by News18 that the mRNA vaccine, including Moderna and Pfizer/BioNTech, seems to be about 88 percent effective against the Delta variant. Vaccines from Johnson & Johnson and AstraZeneca also appear to be about 60 percent effective, he added.

According to research, the Pfizer and AstraZeneca vaccines were found to be only 33 percent effective three weeks after the first dose against symptomatic cases of the Delta variant, compared to 50 percent effective for the Alpha variant.

The World Health Organisation had recently expressed concerns that the Delta variant of COVID-19, the variant first detected in India, is reducing the efficacy of the existing COVID-19 vaccines in the world. India’s top virologist Shahid Jameel also voiced fears that the Delta Plus mutation might be able to evade both immunity from vaccination as well as immunity from earlier infections.

What is the Delta Plus variant?

Around 40 cases of the Delta Plus variant, classified as a variant of concern (VOC), have been detected sporadically in Maharashtra, Kerala and Madhya Pradesh, the Union health ministry said. A ministry statement clarified that no significant in increase of the AY.1 variant has been witnessed. Mysuru has reported the first case of Delta Plus variant of COVID-19 in Karnataka.

The Maharashtra health department warned that the variant may trigger a third COVID-19 wave in the state. “The number of active patients could reach up to eight lakh, while 10 percent out of them could be children,” said the presentation made by the department.

After the report of the Delta plus or AY.1 variant by the Public Health England (PHE) on 11 June, retrospective analysis of samples revealed the first occurrence of this lineage from a sample collected from Maharashtra. The sample was collected on 5 April.

As of 18 June, 205 sequences of AY.1 lineage were detected worldwide, with the USA and the UK having over half of the known cases, the statement said. "Delta Plus variant has been detected in nine countries besides India," Bhushan said. These countries include US, UK, Portugal, Switzerland, Japan, Poland, Russia and China.

The Delta Plus variant is characterised by the K417N mutation in spike protein, the statement said. The spike protein aids the virus to gain receptor-mediated entry into human cells. K417N corresponds to the change of amino acid lysine (K) to asparagine (N) at the 417th position of spike protein.

A statement issued by the Union Health Ministry stated Indian SARS-CoV-2 Genomic Consortia (INSACOG) had informed that the Delta Plus variant, "currently a variant of concern (VOC)", has these characteristics: increased transmissibility, stronger binding to receptors of lung cells and potential reduction in monoclonal antibody response.

According to a Lancet study published on 14 June, the Delta variant posed almost twice the risk of hospitalisation compared to the Alpha variant.

Experts question ‘variant of concern’ tag for Delta Plus

Leading virologists have questioned the labelling of Delta Plus as a variant of concern, saying there was no data yet to prove that the variant was more infectious or led to more severe disease compared to other variants.

"There is no data yet to support the variant of concern claim," Dr Gagandeep Kang, a virologist and the first Indian woman to be elected Fellow of the Royal Society of London, told BBC. "You need biological and clinical information in order to consider whether it is truly a variant of concern."

Even with 166 examples of Delta Plus shared on GISAID, a global open sharing database "we don't have much reason to believe this is any more dangerous than the original Delta," according to Dr Jeremy Kamil, a virologist at Louisiana State University Health Sciences Center in Shreveport.

With inputs from agencies