The continued persistence of SARS-CoV-2 infections in predominantly unvaccinated individuals has meant a continued need for therapeutics to treat those hospitalized with COVID-19. Convalescent plasma containing SARS-CoV-2 neutralizing antibodies from recovered individuals is one therapy option but has been controversial. A new publication in Transfusion by CITF-funded researchers Drs. Steven Drews and Sheila O’Brien of Canadian Blood Services assesses why plasma collected from the first wave of COVID-19 in Canada may have a limited ability to neutralize SARS-CoV-2 variants of concern (VOCs).       

Key points:

Researchers utilized a randomized cross-sectional approach to select 113 specimens from 3000 random plasma samples collected by Canadian Blood Services clinics across Canada between April and May 2020. Nine selected specimens from this group identified with a range of neutralizing antibodies (low to high) against wild-type SARS-CoV-2 were chosen for further analysis to evaluate their abilities at neutralizing SARS-CoV-2 variants such as Alpha, Beta or Gamma. Four of six specimens with high neutralizing titers demonstrated reduced neutralizing capacity against the Beta variant, whereas three of six specimens with high neutralizing titers demonstrated reduced neutralizing capacity against the Gamma variant.

An evaluation of blood samples containing a range of neutralizing antibodies against the original wild-type Wuhan SARS-CoV-2 virus were shown to have reduced capacity to neutralize emerging variants of concern (VOCs) such as Alpha, Beta, or Gamma. It would therefore appear that convalescent plasma (with low or high neutralizing antibodies) from the first wave of the pandemic may serve limited value as a therapy for patients suffering from severe COVID-19 disease in the current scope of the pandemic, which has been transformed by several VOCs.

Overall, this research provides further evidence on the limited utility on convalescent plasma therapy in the evolving COVID-19 pandemic


Drews SJ, Abe KT, Hu Q, Samson R, Gingras AC, Colwill K, Rathod B, Wang J, Fazel‐Zarandi M, Yi QL, Robinson A. Resistance of SARS‐CoV‐2 Beta and Gamma variants to plasma collected from Canadian blood donors during the Spring of 2020. Transfusion. 2021 Oct 18. doi: 10.1111/trf.16713