Our findings support further rational design of PCV2 vaccines to increase the current threshold of protection.
Nevertheless, a high percentage of subjects achieved post-vaccination titers ≥ 1 128 (98.1%), a level considered a conservative threshold of protection.
Hence, natural products with the ability to induce the over-expression of Hsp70 may provide higher threshold of protection against gastric lesions [ 50].
This reference antibody concentration of 0.35 µg/mL was defined by the World Health Organization [ 28] to estimate efficacy of PCVs against IPD for infants and is not a defined threshold of protection for other age groups or for this immunocompromised population.
Figure 1 shows the reverse cumulative distribution of rSBA titers stratified by age group and sex; nearly all participants had rSBA titers well beyond the putative threshold of protection across all strata.
In the study in Africa, we found that 4 years after vaccination with PsA-TT, an overall 90% of subjects are still potentially protected, with the youngest age group, 2 10 years, showing the lowest level above the putative threshold of protection, with 76% of subjects having group A specific IgG concentrations ≥2 µg/mL.
However, it should be noted that there is on-going debate about the validity of current HI immune response thresholds as correlates of protection, and furthermore, HI surrogates are based on studies in adults and there are no accepted correlates specific for children.
Moreover, the percentages of children with rSBA titers ≥ 1 128, which is the more conservative threshold for protection, were also evaluated.
That figure is far below the threshold of minimum protection required by most airlines, and it could have grounded planes worldwide on Tuesday.
OPKA threshold for protection is identified as OI ≥ 8.
The former is a marker of short-term immunity [ 9, 21], and individuals with concentrations above this threshold have evidence of protection against tetanus that is likely to wane within a year.
