Deltacron is not a New Strain or Variant

Deltacron is not a new strain or variant but a case of co-infection with two variants of SARS-CoV-2. Over the past two years, different variants have emerged of the SARS CoV-2 strain with varying degree of infectivity and disease severity. Variants such as delta and omicron are beginning to cause coinfection, leading to media reports labelling them as different strains of the virus. However, this is misleading as it is simply infection caused by a combination of two variants, says Rajeev Soni, a leading Molecular Biologist and Biotechnologist. 

The COVID-19 pandemic caused by the SARS CoV-2 strain of corona virus has crippled the entire world for the past two years, slowing down economies and bringing normal life to a grinding halt. As the virus infects more individuals, new variants arise1 due to mutations in the genetic code. New variants in case of the SARS-CoV-2 virus strain are emerging due to mutations, primarily in the receptor binding domain (RBD) of the spike protein. In addition, deletions of regions within the spike proteins have also been reported. The worst of the variants has been the delta variant that has caused an increase in COVID infections all over the globe, along with increased mortality. Recently, in November 2021, South Africa reported another variant called Omicron, which is 4 to 6 times more infectious than the delta variant, albeit causing less severe disease. Another variant called the IHU variant2 has been identified in France in the past two weeks.  

In addition, there has been report of co-infection of people with the different variants, e.g. delta and omicron. Whether we call the infection Delmicron or Deltacron, an important thing to keep in mind is that these terms refer to the infection caused by a combination of “two variants of the same strain of virus, SARS CoV-2″, and not to be confused as different “strains”, says Dr. Rajeev Soni, an accomplished Molecular Biologist and Biotechnologist, and an alumnus of the University of Cambridge, UK. 

To call the coinfection with different variants, a different strain of virus is misleading. A strain is usually referred to as differing substantially in terms of its biological properties and behaviour, which is certainly not the case with the variants seen so far3. Another coinfection that has been reported is the one with flu virus strain and corona virus strain naming the infection as Flurona. That doesn’t make Flurona a different strain at all. 

In the coming days, more variants will emerge which might lead to more coinfections. However, these should not be termed as different strains of the virus. The nomenclature should only be confined to the disease caused by infection of the involved variants. 



  1. Bessière P, Volmer R (2021) From one to many: The within-host rise of viral variants. PLoS Pathog 17(9): e1009811.  
  1. New ‘IHU’ Variant (B.1.640.2) detected in France. Scientific European Posted 04 January 2022. Available at  
  1. COVID-19 Genomics UK Consortium (COG-UK). Explainer – What do virologists mean by ‘mutation’, ‘variant’ and ‘strain’? 3 Mar 2021. Available at 


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