Some deliveries of quadrivalent flu vaccines will be between one and two weeks late because of an 'unexpected delay' in manufacturing, according to the supplier Sanofi Pasteur.

It follows the supplier’s decision earlier this year to stagger the delivery of its quadrivalent flu vaccines, which are made for 18 to 64-year-olds, after a delay to the World Health Organisation (WHO) strain information. Some vaccines were not due to be delivered until the end of November.

Our sister publication Pulse reported that flu vaccines for over-65s, adjuvanted trivalent vaccine (aTIV), were on time earlier this month, according to supplier Seqirus.

A spokesperson for Sanofi Pasteur said the supplier 'has experienced a small unexpected delay in the final stages of vaccine manufacturing at our main manufacturing plant in France.

‘This has meant 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 to customers ahead of the season.’

They added that the supplier had contacted all customers and were working closely with Public Health England, the Department of Health and Social Care and the NHS to minimise the 'operational challenges'.


Multiple factors


The supplier also said this was a ‘unique’ year in flu vaccine supply.

The spokesperson said: ‘In 2019, multiple factors have contributed to a particularly unique year in influenza vaccine supply. The World Health Organization (WHO) took the decision to select two new influenza virus strains out of the four contained in quadrivalent influenza vaccines.

‘In addition to this, the WHO delayed the selection of one of the strains by one month. While we fully appreciate the WHO decision, this meant Sanofi Pasteur’s vaccine distribution commenced a few weeks later than last season.’

WHO said in March it had delayed it’s decision ‘to better understand the distribution and proportions of recently circulating antigenically and genetically diverse A(H3N2) viruses and to develop and fully characterize appropriate candidate vaccine viruses’.