[55] B. Lorbetskie et al., “Optimization and qualification of a quantitative reversed-phase

HPLC method for hemagglutinin in influenza preparations and its comparative

evaluation with biochemical assays,” Vaccine, vol. 29, no. 18, pp. 3377–3389, Apr.

2011.

[56] J. Transfiguracion, A. P. Manceur, E. Petiot, C. M. Thompson, and A. A. Kamen,

“Particle quantification of influenza viruses by high performance liquid chromato-

graphy,” Vaccine, vol. 33, no. 1, pp. 78–84, Jan. 2015.

[57] B. Kalbfuss, A. Knochlein, T. Krober, and U. Reichl, “Monitoring influenza virus

content in vaccine production: precise assays for the quantitation of hemaggluti-

nation and neuraminidase activity,” Biologicals, vol. 36, no. 3, pp. 145–161, May

2008.

[58] D. D. LaBarre and R. J. Lowy, “Improvements in methods for calculating virus titer

estimates from TCID50 and plaque assays,” J. Virol. Methods, vol. 96, no. 2,

pp. 107–126, 2001.

[59] S. L. Schwartz and A. C. Lowen, “Droplet digital PCR: A novel method for de-

tection of influenza virus defective interfering particles,” J. Virol. Methods, vol.

237, pp. 159–165, Nov. 2016.

[60] A. J. Veach, C. Beard, F. Porter, M. Wilson, and F. B. Scorza, “Digital droplet PCR

for influenza vaccine development,” Procedia Vaccinol., vol. 9, pp. 96–103, 2015.

[61] C. F. Mandenius et al., “Monitoring of influenza virus hemagglutinin in process

samples using weak affinity ligands and surface plasmon resonance,” Anal. Chim.

Acta, vol. 623, no. 1, pp. 66–75, Aug. 2008.

[62] C. E. Nilsson, S. Abbas, M. Bennemo, A. Larsson, M. D. Hamalainen, and

A. Frostell-Karlsson, “A novel assay for influenza virus quantification using surface

plasmon resonance,” Vaccine, vol. 28, no. 3, pp. 759–766, Jan. 2010.

[63] S. Khurana, L. R. King, J. Manischewitz, E. M. Coyle, and H. Golding, “Novel

antibody-independent receptor-binding SPR-based assay for rapid measurement of

influenza vaccine potency,” Vaccine, vol. 32, no. 19, pp. 2188–2197, Apr. 2014.

[64] L. Durous et al., “SPRi-based hemagglutinin quantitative assay for influenza vac-

cine production monitoring,” Vaccine, vol. 37, no. 12, pp. 1614–1621, Mar. 2019.

[65] S. B. Carvalho, C. Peixoto, M. J. T. Carrondo, and R. J. S. Silva, “Downstream

processing for influenza vaccines and candidates: An update,” Biotechnol Bioeng,

vol. 118, no. 8, pp. 2845–2869, Aug. 2021.

[66] I. Manini et al., “Flucelvax (Optaflu) for seasonal influenza,” Expert Rev. Vacc., vol.

14, no. 6, pp. 789–804, Jun. 2015.

[67] European Medicines Agency, “Flucelvax Tetra: EPAR – Public assessment report,”

2018, Available: https://www.ema.europa.eu/en/medicines/human/EPAR/flucelvax-

tetra

[68] K. Wang, K. M. Holtz, K. Anderson, R. Chubet, W. Mahmoud, and M. M. Cox,

“Expression and purification of an influenza hemagglutinin--one step closer to a re-

combinant protein-based influenza vaccine,” Vaccine, vol. 24, no. 12, pp. 2176–2185,

Mar. 2006.

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