About new variants of COVID-19

RNA viruses can infect and replicate in its host cells. During the copying process, small errors may occur occasionally and virus mutation may arise as a result. Mutations are mixed blessing for a virus because not all mutations have a significant impact on its characteristics. Some virus strains (variants) contain mutations that help the virus copy itself or get into human cells easily. SARS-CoV-2 has been evolving and certain mutant variants are concerning due to its potential effect on current drugs and vaccine, diagnostic tools and public health measures.

Variant of concern are those with evidence of increase transmissibility, increase hospitalizations or deaths, reduced effectiveness of treatment or vaccine or diagnostic detection failures.

*On 26 November 2021, WHO has designated B.1.1.529 as a VOC, named Omicron.

Coronavirus’ spike proteins (S protein) engage with human cell receptor, thereby enable an infection. Hence, S protein often serve as the molecular target for developing diagnostic tool and a vaccine candidate. If a variant contains mutations that change the protein structure, it may increase COVID-19 pandemic severity. ii Nature revealed that the Delta variant is around 60% more transmissible than the already highly infectious Alpha variant. A UK study found that a single dose BioNTech's vaccine reduced a person’s risk of developing COVID-19 symptoms caused by the Delta variant by 33%, compared to 50% for the Alpha variant. A second dose of BioNTech were 88% effective (compared to 93% against Alpha). Another study found that people who have had one vaccine dose are 75% less likely to be hospitalized, compared with unvaccinated individuals, and those who are fully protected are 94% less likely to be hospitalized.

According to the Department of Health (Hong Kong), both Comirnaty(BioNTech) and Sinovac COVID-19 vaccines are highly effective in protecting against severe diseases and death from COVID-19 infection, which is generally related to T-cell response. The antibody response is related to prevention of infection and symptomatic disease. It is also more susceptible to Variants of Concern. Therefore, it may differ among different vaccines.