Estimating seroprevalence of vaccine-preventable infections: is it worth standardizing the serological outcomes to adjust for different assays and laboratories?

Abstract

The aim of the European Sero-Epidemiology Network 2 (ESEN2) project was to estimate age-specific seroprevalence for a number of vaccine-preventable diseases in Europe. To achieve this serosurveys were collected by 22 national laboratories. To adjust for a variety of laboratory methods and assays, all quantitative results were transformed to a reference laboratory's units and were then classified as positive or negative to obtain age-specific seroprevalence. The aim of this study was to assess the value of standardization by comparing the crude and standardized seroprevalence estimates. Seroprevalence was estimated for measles, mumps, rubella, diphtheria, varicella zoster and hepatitis A virus (HAV) and compared before and after serological results had been standardized. The results showed that if no such adjustment had taken place, seroprevalence would have differed by an average of 3·2% (95% bootstrap interval 2·9-3·6) although this percentage varied substantially by antigen. These differences were as high as 16% for some serosurveys (HAV) which means that standardization could have a considerable impact on seroprevalence estimates and should be considered when comparing serosurveys performed in different laboratories using different assay methods.

Identifying geographic areas at risk of rubella epidemics in Japan using seroepidemiological data

“…For instance, our study revealed that region 5, which contains Aichi, had the highest effective reproduction number at 2.48, and region 8 (Shikoku island, which is considerably aged compared with the five urbanized regions) yielded the lowest value at 1.01. Similar seroepidemiological evaluations have also been conducted elsewhere ( Pebody et al, 2000 , Kafatos et al, 2015 , Abrams et al, 2016 ). Additionally, accounting for the number of travelers, the highest probability of a major epidemic in our hypothetical scenario was estimated to be 1.00 in region 3, which includes Tokyo, and the lowest probability was estimated to be 0.01 in region 8.…”

Seroepidemiology: an underused tool for designing and monitoring vaccination programmes in low‐ and middle‐income countries

“…Estimates of the spatiotemporal dynamics of individual and population immunity to a variety of pathogens would be a powerful tool for public health programmes and will be facilitated by further improvements in laboratory assays to make them more user‐friendly in low‐income settings , standardising laboratory assays to make it easier to compare studies in different locations , continuing development of statistical approaches to analysing serological data including accounting for waning antibody levels over time , and studies to clarify the relationship between antibody levels, the number of doses of multidose vaccines received and the duration since the last dose.…”

Single-Dose Hepatitis A Immunization: 7.5-Year Observational Pilot Study in Nicaraguan Children to Assess Protective Effectiveness and Humoral Immune Memory Response

“…The early loss of measurable antibody within a few years after a single priming dose in 8 noninfected children (8.3%) has been described for up to a third of adult travelers [14,15,21] and is somewhat higher than the results found in a large Argentinian study [22], in which antibody levels became unmeasurable within 5 years after a single priming dose in only 2.5% of children [22]. The somewhat variable course of the antibody levels in the vaccinated, noninfected children-falling slightly from 2005 to 2006 and then rising again to a maximum in 2007, before finally declining toward the trough level of 2012-may be ascribed to the fact that not all serum samples could be measured in parallel (see Methods), amplified by the assay variability inherent in immune assay testing [23].…”

“…Seronegativity was not retested before vaccination, leaving space to scrutinize whether all 25 HAV infections between 2003 and 2005 had occurred before vaccination; the anti-HAV IgM testing performed 3 months after vaccination showed, however, that the HAV infections detected serologically had most likely occurred before the first vaccination, because the infectioninduced, short-lived (3-6 months) anti-HAV IgM antibodies were either not measurable (n = 23) or borderline (n = 2) at this time point [4]. Although not all sequential serum samples obtained from each child could be tested in parallel, all anti-HAV measurements were done by the same expert (G. F.), using the same immune assay test system in the same laboratory, thus minimizing the variability inherent to anti-HAV antibody measurement with enzyme immune assays [23].…”