NEW YORK (REUTERS) - Moderna said on Thursday (Aug 5) that its Covid-19 shot was about 93 per cent effective four to six months after the second dose, showing hardly any change from the 94 per cent efficacy reported in its original clinical trial.
However, it said it still expects booster shots to be necessary ahead of the winter season as antibody levels are expected to wane. It and rivals Pfizer and BioNTech have been advocating a third shot to maintain a high level of protection against Covid-19.
During a second-quarter earnings call, Moderna CEO Stephane Bancel said that the company would not produce more than the 800 million to 1 billion doses of the vaccine that it has targeted this year.
"We are now capacity constrained for 2021, and we are not taking any more orders for 2021 delivery," he said.
Moderna shares fell 3.6 per cent to around US$403.87 (S$545) in pre-market trading after closing at US$419.05 on Wednesday.
That compares favourably with data released by rivals Pfizer and BioNTech last week in which they suggested their vaccine's efficacy waned around 6 per cent every two months, declining to around 84 per cent six months after the second shot.
Both the Moderna and Pfizer-BioNTech vaccines are based on messenger RNA (mRNA) technology.
"Our Covid-19 vaccine is showing durable efficacy of 93 per cent through six months, but recognize that the Delta variant is a significant new threat so we must remain vigilant," Moderna chief executive Bancel said.
The comment comes as public health officials across the world debate over whether additional doses are safe, effective and necessary even as they grapple with the fast-spreading Delta variant of the coronavirus.
Meanwhile, Pfizer is planning to seek authorisation for a third shot later this month, and some countries like Israel have begun or plan to start administering shots to older or vulnerable people.
Separately, Moderna said its studies of three different booster candidates induced robust antibody responses against variants, including the Gamma, Beta and Delta variants.
It said neutralising antibody levels following the boost approached those observed after the second shot.
For this year, Moderna has signed vaccine contracts worth US$20 billion (S$27 billion) in sales and aims to produce between 800 million and one billion doses.
It has agreements for US$12 billion in 2022, with options for another roughly US$8 billion in sales and expects to produce between two billion and three billion doses next year.
The company, however, has not been able to keep pace with the production of much larger rival Pfizer, which expects to manufacture as many as three billion doses this year, and expects 2021 sales to top US$33.5 billion.
Moderna's vaccine was authorised for emergency use in adults in the US in December and has since been cleared for emergency or conditional use in adults in more than 50 countries.
The company started the process of filing for full approval with the US Food and Drug Administration in June and expects to finish its submission in August.
It posted second-quarter sales of US$4.4 billion, slightly above expectation of US$4.2 billion drawn from 10 analysts polled by Refinitiv. Its Covid-19 shot is the firm's first authorised product and sales were just US$67 million a year earlier.
Moderna earned US$2.78 billion, or US$6.46 a share, beating quarterly expectations of US$5.96 a share.