In a message sent to practices last week, manufacturer Sanofi Pasteur said it had 'experienced a small unexpected delay in the final stages of vaccine manufacturing'.
The company said that 'the phasing of 40% of the first deliveries of Sanofi Pasteur’s quadrivalent influenza vaccine will be one to two weeks behind that previously communicated'.
It warned that 2019 had been 'a particularly unique year in influenza vaccine supply' after the World Health Organisation (WHO) include two new virus strains in the four covered by quadrivalent influenza vaccines, and 'delayed the selection of one of the strains by one month'.
A late start to the vaccine manufacturing process and high demand had increased pressure, the company said.
A spokesperson said: 'We have informed all customers who have ordered our quadrivalent influenza vaccine directly from us, along with all large pharmacy chains, and as always we are working closely with all our stakeholders across Public Health England (PHE), the DHSC and the NHS to ensure that any operational challenges are minimised.'
GPonline reported last month that deliveries of the flu vaccine for patients aged over 65 had begun. Seqirus, the manufacturer of the adjuvanted trivalent inactivated vaccine (aTIV) recommended for patients in this age group, has said deliveries will be complete before 31 October - the date on which the UK is scheduled to leave the EU.
In 2018, some GPs struggled to secure supplies of the vaccine for over-65s and were ordered to share supplies between practices in some areas.