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TGA Laboratories testing report: Seasonal influenza vaccines - Batch release 2020

28 August 2020


The TGA monitors the potency and consistency of production of influenza vaccines entering the Australian market. This is a routine activity and is not conducted in response to any specific safety concern. This report provides information on the2020 season.

There are three major types of influenza viruses: Influenza A virus, Influenza B virus and Influenza C virus, with viruses in the first two of these types being the major causes of influenza in humans.

Seasonal influenza vaccines registered in Australia usually contain four strains of virus: two type A strains (H1N1 and H3N2) and two type B strains (B/Victoria and B/Yamagata lineage viruses). The most common way that flu vaccines are made is using an egg-based manufacturing process although the cell-based production process is an alternative platform that has been developed. Seasonal vaccine composition changes on an annual basis to account for the rapid antigenic changes to the influenza virus.

For the 2020 Southern Hemisphere influenza season, a total of 17.6 million doses of influenza vaccines were supplied to the Australian market, with six products available on the Australia market and a further 1.8 million doses for export (See 2020 seasonal influenza vaccines). The 2020 season saw an unprecedented demand for influenza vaccines, with an additional 5 million doses released in Australia compared to in 2019. This is the largest number of vaccine doses ever to be released by TGA in a single season (See Figure 1).

Figure 1: Total number of Influenza doses released by TGA between 2012 and 2020
Figure 1: Total number of Influenza doses released by TGA between 2012 and 2020


The TGA monitors influenza vaccines by testing using a method called Single Radial Immunodiffusion (SRID). This method measures the amount of haemagglutinin (HA) in the samples. The amount measured in each vaccine needs to be within the required range, and consistent over time. When used in conjunction with the vaccine manufacturer's data, TGA's testing results provide insights into the quality and consistency of influenza vaccine production.

The Influenza Vaccine Batch Release Program for the 2020 season tested a total of 47 samples for haemagglutinin content using SRID. These vaccines were supplied to TGA during the course of the Southern Hemisphere 2020 season and represented batches across all products supplied. All samples tested met the relevant approved release specifications for the product and the internationally recognised standard of the European Pharmacopoeia.


The vaccines tested under the current project were representative of the Final Bulk Vaccines (FBVs) used in the manufacture of the 19.4 million doses of influenza vaccines processed by TGA for batch release for both domestic and export markets. The doses released were from seven products (six for the Australian market, and one for export) and all samples tested from these products met the relevant specifications for haemagglutinin (HA) content i.e. Lower Confidence Limit of the estimate HA content is > 80% of the label claim.

The data collected through the testing program identified no quality/consistency issues with the potency of the vaccines. All samples were found to be of acceptable quality for the test applied, complying with the approved specifications for HA content. TGA testing data were also comparable to the manufacturer's data and showed that, across the manufacturing season, production was consistent.

In addition to the described laboratory testing, the TGA Laboratories program has assessed the manufacturing and/or cold chain records for all batches of influenza vaccine supplied in Australia through the batch release program, which assessed the quality of individual batches before distribution.