Divulging Incipient SARS-CoV-2 Delta (B.1.617.2) Variant: Possible Interference with Global Scenario

Area of Science:

• Virology
• Epidemiology
• Infectious Diseases

Background:

• The SARS-CoV-2 Delta variant (B.1.617.2) emerged in India in late 2020.
• It rapidly became the dominant variant globally by mid-2021.
• Designated by the WHO, Delta exhibits increased transmissibility and potential for more severe disease.

Purpose of the Study:

• To summarize the characteristics of the SARS-CoV-2 Delta variant.
• To assess its transmissibility, pathogenicity, and global spread.
• To review emerging evidence on its impact on immunity and treatments.

Main Methods:

• Literature review and data synthesis on variant surveillance.
• Analysis of epidemiological data on transmission rates and disease severity.
• Review of laboratory studies on immune escape and therapeutic resistance.

Main Results:

• Delta is 40-60% more transmissible than Alpha and twice as transmissible as the original strain.
• Evidence suggests Delta may cause more severe illness in unvaccinated individuals.
• Increased transmissibility, secondary attack rate, hospitalization risk, and immune escape are associated with Delta.
• Neutralization efficiency in vaccinated individuals and resistance to monoclonal antibodies have been observed.

Conclusions:

• The Delta variant represents a significant public health concern due to its enhanced transmissibility and potential for increased severity.
• Further research is needed to fully understand its impact on vaccine effectiveness and therapeutic interventions.
• Global surveillance and rapid response are crucial to manage the spread of concerning variants like Delta.