Moderna says vaccine 93% effective but seeks 3rd-shot in fall

Moderna Inc said its Covid-19 vaccine remained 93% effective through six months after the second shot but pointed to the likelihood of the need for a third-dose booster in the fall.

The company attributed the need for a booster shot to what it calls "increased force of infection" resulting from the highly contagious Delta variant that is expected to push up the number of breakthrough infections in vaccinated individuals.

"We are pleased that our Covid-19 vaccine is showing durable efficacy of 93% through six months, but recognise that the Delta variant is a significant new threat," Moderna CEO Stephane Bancel said Thursday as the company reported its second-quarter earnings and revenue. 

Antibody levels are expected to "continue to wane and eventually impact vaccine efficacy," which leads to the view that a third booster shot will likely be necessary before the winter season," the Massachusetts-based firm said.

Moderna's vaccine, which uses a new technology known as messenger RNA, was the second type of two-dose vaccines that were granted emergency use authorisation by the US drug regulator in December last year.

The company's latest analysis of a clinical trial showed the vaccine had a 93.2% efficacy against Covid-19, the respiratory illness caused by the virus, and 98.2% efficacy against severe symptoms, with no deaths reported.

But the data does not include the vaccine's performance against the Delta variant, first detected in India.

So far, Bangladesh has administered at least 14,733,314 doses of Covid vaccines – including 110,1897 Moderna shots.

There are many variants of SARS-CoV-2 that can cause Covid. Each variant is the result of a random mutation of the original virus.

The main variant of concern now in Bangladesh, and indeed worldwide, is the Delta variant. This variant spreads more quickly than the original virus, increasing the number of hospitalisations or deaths.