Vaccine giant Merck pulls plug on Covid trials

Two vaccine candidates fail to deliver strong enough results to challenge rivals

US vaccine giant Merck is discontinuing development of its two experimental Covid-19 vaccines after early trial data showed they failed to generate immune responses comparable to a natural infection or existing vaccines.

The US drug giant, known in Ireland as MSD, has a history of successfully developing vaccines, and had adopted a different strategy from rivals Pfizer, Moderna and Johnson & Johnson, using a more traditional approach of focusing on shots based on weakened viruses.

Merck received interim results from its early-stage trials this month.

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The results were "disappointing, and a bit of a surprise", said Nick Kartsonis, senior vice-president of clinical research for infectious diseases and vaccines at Merck Research Laboratories.

Both shots generated fewer neutralising antibodies to halt infection than other Covid-19 vaccines, and produced inferior immune responses compared with people who had naturally contracted the coronavirus.

“We didn’t have what we needed to be able to move forward,” Mr Kartsonis said in an interview Sunday.

After evaluating the data, Merck’s senior leadership decided to discontinue the programmes and divert resources to the company’s efforts to develop Covid-19 treatments. – Bloomberg