COVID-19 Delta Strain Could Affect the Mass Immunity Threshold

The SARS-CoV-2 virus behaves like any other virus in the sense that with each host infected, it seeks to mutate and develop stronger strains. Stronger strains can infect new hosts faster, become more contagious, and trick the immune system into creating fewer antibodies to fight off the infection. Some of the SARS-CoV-2 variants have been given Greek names and categorized by the World Health Organization as variants of concern (VOC) and variants of Interest (VOI). 

The Delta variant has been classified as VOC

Along with the Alpha, Beta and Gamma, the Delta strain (B.1.617.2), which originated in India in October 2020, has been classified as a variant of concern. This means that WHO’s research indicated that this SARS-CoV-2 variant had suffered genetic changes that makes it more contagious. With a higher transmissibility rate, more severe symptoms, and more therapeutic help, even hospitalization, it is clear the Delta strain is the most potent mutation yet. The Delta strain is the dominant variant in the U.S, and it is a major risk to our health. 

Herd immunity threshold might need to be changed

Until now, experts believed that in order to reach herd immunity and control the Covid-19 pandemic, it would be necessary for 80% of the world’s population to be fully vaccinated with the available Covid-19 vaccines. However, to stop the spread of the highly contagious Delta strain, it might be necessary for more than 80% of the world’s population to get the vaccine, experts believe. In many countries, children under 12 years old are not eligible for Covid-19 vaccines yet, which might make the mission even more difficult. The original SARS-CoV-2 virus from Wuhan required 67% of the world’s population to be fully vaccinated. The Delta strain required around 90% of the population to be vaccinated to reach the mass immunity goal.