In fi­nal analy­sis, J&J's un­der­dog vac­cine of­fers on­ly 52.9% pro­tec­tion against Covid-19

It’s long been es­tab­lished that the sin­gle-shot vac­cine pro­duced by J&J is nowhere near as ef­fec­tive as two dos­es of the mR­NA vac­cine — ini­tial­ly viewed as a trade­off be­tween ac­ces­si­bil­i­ty and ef­fi­ca­cy.

But as sci­en­tists re­vealed in their fi­nal analy­sis of J&J’s Phase III study, the vac­cine may be even less ef­fec­tive in the longer term.

Af­ter track­ing about 39,000 par­tic­i­pants for a me­di­an of four months (8,940 of whom had at least six months of fol­low-up), re­searchers con­clud­ed in a pa­per pub­lished on the New Eng­land Jour­nal of Med­i­cine:

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