An interesting preprint by Kim and others looked at this subject. 

Recent mutations in SARS-CoV-2 have raised concerns about diminishing vaccine effectiveness against COVID-19 caused by particular variants.  

Even with a high initial efficacy, if a vaccine’s efficacy drops significantly against variants, or if it cannot be distributed quickly, it is uncertain whether the vaccine can provide better health outcomes than other vaccines.  

This preprint tried to evaluate the trade-off between speed of distribution versus efficacy of multiple vaccines where variants emerge.  

They found that a vaccine with low efficacy both before and after variants may outperform a vaccine with high efficacy if the former can be distributed quickly. 

Particularly, a vaccine with 65% and 60% efficacy before and after variants, respectively, can outperform a vaccine with 95% and 90% efficacy if its distribution is 46% to 48% faster. 

Overall, their results suggested that the administration of a vaccine with high efficacy against both the original strain and the variants may not always lead to a low number of cumulative infections if it cannot be distributed as quickly as other vaccine types with lower efficacies.  

Despite the vast efforts for worldwide vaccination, vaccine distribution has been an ongoing challenge due to production shortages, economic constraints and the lack of ultra-cold chain infrastructure.  

Due to these challenges, especially many low and middle income countries have not received a single dose of vaccine as of February 2021. 

They suggested it is critical to distribute available vaccines as quickly as possible and vaccinate more people to reach herd immunity before new variants spread.  

Their study demonstrated that a vaccine with a relatively lower efficacy can achieve at least as good health outcomes as their higher efficacy counterparts, as long as it is distributed more quickly. 

The London General Practice commends the government on its vaccination programme and encourages all to be vaccinated when eligible.

Dr Paul Ettlinger

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