A new virus causing respiratory illness was reported in Wuhan, China in early December 2019. On January 30, 2020 WHO designated SARS-CoV-2 was designated a Public Health Emergency of International Concern and on March 11, 2020 it declared it a pandemic.
The virus subsequently spread to all provinces of China and to more than 150 countries around the world and in the year that followed saw over 110 million cases and 2.5 million deaths worldwide along with unprecedented lockdowns, quarantines and economic devastation. In early 2021 several vaccine candidates have been approved by regulatory authorities which provide a light at the end of the tunnel, but what do the emergence of new SARS-CoV-2 variants mean for vaccination and the end of the global pandemic?
The SARS-CoV-2 variants
The following are the most notable variants as of Feb 2021:
- The UK variant (201/501Y.V1, VOC202012/01, B.1.1.7)
- The South African variant (20H/501Y.V2, B.1.351)
- Brazilian variant (P.1)
Both the UK variant and the South African variant have a mutation (N501Y) in the receptor binding domain of the spike protein that is reported to contribute to increased transmission with estimates ranging between 40% and 70% for increased transmission. There is no evidence that the UK strain has any increased clinical severity of illness.1 The South African variant has two additional mutations in the spike protein that confer a potential immune escape to antibodies.2 On February 18, 2021 Pfizer and Moderna confirmed that their vaccines appear to be highly effective against the UK variant but have a decreased ability to neutralize the South African strain.3
Additionally, a recombination event between the UK variant and a California variant (B.1.429), which is also reportedly able to resist some antibodies, has been detected.4 With the emergence of more variants of SARS-CoV-2, recombination may pose a bigger threat since it results in the genetic material of the strains being spliced together combining multiple mutations at once. This could result in a more lethal, antibody-resistant hybrid but the reverse is also possible with recombination events occurring at a cost to the virus.
With many unknowns surrounding new strains, escape mutants, and recombination events, the simple acts of mask wearing, quarantining and social distancing are still our best defense as the foot race between the virus and the science continues.