Polio and Pertussis Immunity Testing

Introduction to Immunity Testing

The Centers for Disease Control and Prevention (CDC) recommends testing for neutralizing antibodies against the three poliovirus serotypes (types 1, 2, and 3) as the gold standard for assessing polio immunity 1
Neutralizing antibody tests are the only CDC-endorsed method for determining immunity to poliovirus, with a protective level of antibody indicating immunity against poliomyelitis 1, 2

Serum specimens are collected and tested for neutralizing antibody to each of the three poliovirus serotypes, using the standard protocol for poliovirus serology as recommended by the CDC 1, 2
A fourfold rise in antibody titer between acute-phase and convalescent-phase serum specimens is diagnostic for poliovirus infection, not immunity 1, 2
For immunity assessment, a single serum sample showing protective antibody levels is sufficient, and the CDC Enterovirus Laboratory is available for consultation and testing of specimens 1

Pertussis immunity is typically assessed through serologic testing for antibodies against pertussis antigens, with diagnosis of pertussis infection by serology generally requiring demonstration of a substantial change in titer (usually fourfold) when comparing results from acute and convalescent sera 3
Single sample serologic assays for pertussis immunity lack standardization in most settings, and none of these serologic assays is licensed by FDA for routine diagnostic use in the United States 3
After receiving the 5-dose DTaP series, protection against pertussis reaches its peak at 98.1% effectiveness within the first year, with protection waning over time to approximately 71.2% by ≥5 years after the fifth dose 5

In the United States, IPV (inactivated poliovirus vaccine) is the only recommended vaccine for prevention of poliomyelitis, with most individuals developing protective levels of antibodies against all three poliovirus serotypes after a complete vaccination series 1, 2
Pertussis immunity wanes more rapidly than tetanus or diphtheria immunity, with booster doses required to maintain immunity against pertussis 5
The complete 5-dose DTaP series has an estimated overall effectiveness of 88.7% against culture-confirmed pertussis disease, with vaccine efficacy estimates ranging from 79% to 89% after 3 doses of DTaP 5

For pertussis, the CDC does not endorse serologic testing for routine diagnostic use due to lack of standardization, and for polio, assays other than neutralization tests should be interpreted with caution due to inadequate standardization 1, 3
When assessing immunity in individuals vaccinated outside the United States, different vaccination schedules may need to be considered, as recommended by the CDC and other guideline societies 6