WHO logoWhen confronting an onslaught of new SARS-CoV-2 variants, COVID-19 vaccine makers such as Pfizer (NYSE:PFE) and Moderna (NSDQ:MRNA) have tested tweaked versions of their vaccines but ultimately decided that they were unnecessary.

Signs are growing that vaccines developed based on the original strain of the novel coronavirus will struggle to offer durable protection against the omicron variant.

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