As the highly infectious Delta variant challenges pandemic control efforts around the world, it raises a huge question: Whether the virus behind the worst pandemic in a century will evolve to become more or less threatening in terms of its harmfulness to humans health, and resistance to vaccines.
Scientists widely agree that new mutations of Sars-CoV-2 are likely to emerge as time goes on, and will continue to circulate in some form or another for years to come, but there is no way of knowing exactly how it will evolve, and not all mutations are necessarily more dangerous or concerning
While there is evidence that the Delta variant is more easily transmitted among vaccinated people than the original Wuhan strain, none of the variants has been proven to render vaccines ineffective at preventing serious illness and death.
- Early research from the U.K. suggests that, after full vaccination, the Pfizer-BioNTech COVID-19 vaccine is 88% effective at preventing symptomatic COVID-19 virus caused by the delta variant. The vaccine is 96% effective at preventing severe disease with the COVID-19 virus caused by the delta variant. The research also showed that the vaccine is 93% effective at preventing symptomatic COVID-19 virus caused by the alpha variant.
- Early research from Canada suggests that, after one dose, the Moderna COVID-19 vaccine is 72% effective at preventing the symptomatic COVID-19 virus caused by the delta variant. One dose of the vaccine is also 96% effective at preventing severe disease with the COVID-19 virus caused by the delta variant.
- The Janssen/Johnson & Johnson COVID-19 vaccine is 85% effective at preventing severe disease with the COVID-19 virus caused by the delta variant, according to data released by Johnson & Johnson.
Polly Roy, a professor of virology at The London School of Hygiene and Tropical Medicine, said “A timeline is impossible to predict but most pandemics in the past have run out of steam after a couple of years so that sort of timescale may be realistic. Most variants will not have too much impact on the current vaccines and will still be controlled by vaccination… So, we have no reason to panic”
However, other experts have sounded more alarming warnings about the threat of mutant strains, particularly the risk of a variant emerging that is resistant to current vaccines.
Nikolaus Osterrieder, dean of the Jockey Club College of Veterinary Medicine and Life Sciences at City University in Hong Kong, said past experience suggested new variants would be more transmissible and resistant to vaccines. “Simply speaking, viruses don’t have any benefit from becoming more virulent, they are only ‘interested in’ survival and spread,” said Osterrieder. But Osterrieder said the emergence of new variants did not change the need for societies to learn to live with the virus and its mutations.
Su, the Duke-NUS Medical School professor, said there was little evidence to assume viruses become less virulent over time and that the reduced impact of certain diseases could be the result of increased immunity due to infection or vaccination.
High vaccination rates would be crucial to getting back to normality, Su said. “The rate of vaccination needs to increase if we want to live with the virus,” she said
Mayoclinic, Do COVID-19 vaccines protect against the variants?
South China Morning Post, Delta variant’s global spread raises the question: will Covid-19 become more infectious?