Virus mutation concerns grow for Covid-19 vaccines

NEW DELHI: A particular mutation of the Sars-Cov-2 virus is established to lower the efficacy for vaccines, the results announced by Novavax on Thursday and Johnson & Johnson on Friday showed, reinforcing concerns that the inoculations may need to be updated to fight these new variants.

The results also appear to reinforce the notion that vaccines that elicit higher immunogenicity – measured as antibody titers -- could be leading to higher efficacy. These insights are crucial as countries strike deals and prioritise different vaccines, particularly as they race to stay ahead of the coronavirus’s evolution.

The mutation particularly worrying experts is known as E484 and occurs in the spike protein, the component of the virus used to enter target cells. It has been found in two widely spreading variants – the B.1.351 in South Africa and P.1 in Brazil.

Novavax, which said its dose was 96% effective in preventing disease with the older variant, said the efficacy dropped to 60% in a small trial in South Africa where B.1.351 accounted for most infections. In the case of the J&J-Janssen dose too, the efficacy rate was 57% (for the SA strain) compared to 72% in the US, where infections were with the older variant.

“Novavax initiated development of new constructs against the emerging strains in early January and expects to select ideal candidates for a booster and/or combination bivalent vaccine for the new strains in the coming days.

The company plans to initiate clinical testing of these new vaccines in the second quarter of this year,” the company said in a statement, confirming that it had started work on updating the dose.

On January 25, Moderna became the first to begin work to account for the new mutation, after reporting that it had seen a drop in immunogenicity in lab tests when the South African variant was used.