Updated 6pm

Pfizer expects lower coronavirus vaccine deliveries for a stretch beginning in late January in order to lift output later this winter and throughout 2021, the drugmaker said Friday.

The pharmaceutical giant aims to boost its overall production levels of the Covid-19 vaccine to two billion doses in 2021, necessitating regulatory approvals over its manufacturing processes.  

"There may be fluctuations in orders and shipping schedules at our Puurs (Belgium) facility in the immediate future to quickly enable the increased production volumes," the company said.

The US market, which is supplied by Pfizer's Kalamazoo, Michigan manufacturing site, will not be affected by the fluctuation in deliveries, a company spokesperson said.

"Although this will temporarily impact shipments in late January to early February, it will provide a significant increase in doses available for patients in late February and March," the company said.

Six EU health ministers signed a letter to the European Commission on Friday to express "severe concern" over the delivery delays for the coronavirus vaccine developed by BioNTech and Pfizer.

EU chief Ursula von der Leyen said Pfizer's CEO had guaranteed the delivery of all doses of the coronavirus ordered by the bloc for the first quarter of 2021. 

Norway, which is not part of the EU, said that it had been told by Pfizer that it would receive 36,075 vaccine doses next week, down from the 43,875 previously expected, or a 17.8 per cent drop.

n order to compensate for the reduction, Norway will use some of the vaccine doses it had put aside as a precaution when it received its first allotments.

"We ... have the possibility to compensate for the reduction in deliveries thanks to the emergency stocks we have in Norway," the director of infectious disease prevention at Norway's public health institute, Geir Bukholm said in the statement.

"These stocks will enable us to cover the reduction for the next couple of weeks, if necessary," he said.