The development of the long-lasting insecticidal net (LLIN) technology was crucial in making insecticide-treated mosquito nets (ITN) the primary tool for malaria prevention in Africa it is today. Initially, only two brands were available, the polyethylene-based Olyset™ Net which obtained an interim recommendation for public health use from the World Health Organization (WHO) Pesticide Evaluation Scheme (WHOPES) in 2001 [
1] and the polyester-based PermaNet
® 2.0 which obtained interim WHOPES recommendation in 2003 [
2]. However, as the implementation of LLIN mass distribution campaigns picked up after this approach had been shown to provide high and equitable coverage [
3], more LLIN brands came on the market. By 2007 two polyethylene-based LLIN products, DuraNet© and Netprotect
® [
4] and one polyester-based brand, Interceptor
® [
5] had received interim WHOPES recommendations and by end of 2015 there were 13 pyrethroid LLIN brands with at least interim WHOPES recommendation (excluding LLINs with the synergist piperonyl butoxide (PBO) to counter increasing insecticide resistance against pyrethroids), six polyester-based and seven polyethylene-based [
6‐
8]. Some of these LLIN products never made it to the market such as the polypropylene-based Lifenet
®, which combined the softer textile structure of polyester, often preferred by consumers, with the strength of a monofilament yarn similar to polyethylene. But the product could not compete with other LLIN brands due to the higher price of the material. Others are products that share the same specifications and received WHOPES recommendation by extension of recommendations previously given to the “original” product. This applies to MAGNet
® and Royal Sentry
® [
7] which are based on the DuraNet© specification, Yorkool
® [
6] and Yahe
® [
8] based on PermaNet
® 2.0, and SafeNet
® [
8] based on the Interceptor
® LLIN. Since 2017, evaluation of vector control products is centralized with WHO’s Prequalification Team and as of August 2020 the list of prequalified LLIN products includes 13 conventional pyrethroid LLINs and eight “next generation” LLIN products with either the synergist PBO added or a second active ingredient [
9].
With increasing demand for public health use of LLIN and increasing competition among manufacturers, prices not only significantly decreased over time (in part due to reduced prices of oil-based raw materials), but also varied significantly between products [
10]. This then raised the question whether any specific LLIN brand might have a better “value for money” or “cost per year of useful life” than another brand, i.e. considering not only the absolute price per unit, but also the insecticidal and physical durability of the product in the field. While this notion was widely accepted in general and included in the procurement guidelines for pesticide products by the WHO [
11], its implementation was hindered by the fact that the initial methodology for field testing LLINs focused on the insecticidal effectiveness and aspects of physical decay were poorly understood [
12]. This changed in 2013 with the approval of a revised methodology for monitoring physical LLIN durability in the field by the Malaria Policy Advisory Committee (MPAC) that combined attrition (loss) of nets due to discarding or destruction with a robust and standardized measure of integrity of surviving nets [
13].
Available data on the physical survival of LLIN in the field show a wide variation in “useful life” between locations or in different use environments ranging from less than 2 years [
14,
15] to four or more [
16‐
19]. Some limited data exists comparing performance of two or more LLIN brands in the same or similar use environments and the results are mixed. Some found differences [
15,
20‐
23] while others did not [
24,
25]. A recent multi-country and multi-brand secondary analysis of data from the VectorWorks project funded by the U.S. President’s Malaria Initiative suggests that a simple categorization by material (polyethylene vs. polyester) and weight of yarn (denier) is not sufficient to describe performance differences between LLIN brands and a more nuanced metric is needed which better reflects the mechanisms of mosquito net damage under “normal” or reasonable day-to-day use [
26]. Such a composite textile performance metric has now been proposed as the resistance to damage (RD) score [
27]. This study uses the previously mentioned VectorWorks-generated data to explore whether the RD score obtained from pre-distribution textile testing can be used as a predictor for LLIN field performance adjusting for other elements of net use environment.