Three quality control (QC) serum pools were prepared by mixing equal volumes of serum from four healthy young adults (12 total donors, aged 22–34 years) 1 month after vaccination with PPV23 (Pneumovax; Merck & Co., Inc., Whitehouse Station, NJ, USA). The serum pools were expected to have variable opsonic indices (OIs) for each serotype.
A total of 42 serum samples were collected from healthy adults aged 20–50 years. Of these samples, 35 samples were obtained 14 to 27 days after immunization with PPV23 (Prodiax23®; Merck & Co., Inc.) by intramuscular injection (group 1). Seven samples were obtained from subjects immunized previously (46 to 123 months prior) with PPV23 (Prodiax23®) (group 2). OIs for 11 additional non-PCV13 serotypes were studied for 42 serum samples. The accuracy of MOPA was studied using 20 selected sera because of the limited volume for analysis.
Collected samples were stored frozen at −70°C until testing. All serum samples were heat-inactivated at 56°C for 30 minutes to inactivate endogenous complement activity and confirmed as antibiotic-free in test cultures with a rough pneumococcal strain (R36A).
A total of 42 serum samples were collected from healthy adults aged 20–50 years. Of these samples, 35 samples were obtained 14 to 27 days after immunization with PPV23 (Prodiax23®; Merck & Co., Inc.) by intramuscular injection (group 1). Seven samples were obtained from subjects immunized previously (46 to 123 months prior) with PPV23 (Prodiax23®) (group 2). OIs for 11 additional non-PCV13 serotypes were studied for 42 serum samples. The accuracy of MOPA was studied using 20 selected sera because of the limited volume for analysis.
Collected samples were stored frozen at −70°C until testing. All serum samples were heat-inactivated at 56°C for 30 minutes to inactivate endogenous complement activity and confirmed as antibiotic-free in test cultures with a rough pneumococcal strain (R36A).