Indirect Test Method Research Articles

Indirect Tensile Strength Test on Heterogeneous Rock Using Square Plate Sample with a Circular Hole

Abstract An indirect testing method for determining the tensile strength of rock-like heterogeneous materials is proposed. The realistic failure process analysis method, which can consider material inhomogeneity, is applied to model the failure process of the square plate containing a circular hole under uniaxial compression. The influence of plate thickness and applied loads on the maximum tensile stress is investigated, and the tensile strength equation is deduced. Meanwhile, the initial cracking loads are obtained by the corresponding physical tests, and the tensile strengths are determined by substituting the initial cracking loads into the developed tensile strength equation. The values predicted by the newly proposed method are almost identical to those of the direct tensile tests. Furthermore, the proposed method can give the relatively small tensile strength error with the direct tensile test in comparison to the other test methods, which indicates that the proposed method is effective and valid for determining the tensile strength of rock-like heterogeneous materials.

Assessment of select direct and indirect pozzolanic reactivity test outcomes with robust regression and ranking analysis

The use of pozzolanic materials as a sustainable partial replacement option for portland cement in concrete has been extensively studied over the last few decades. This study aimed to assess the pozzolanic reactivity of seven different powdered materials: pottery cull, brick powder, lightweight aggregate fines, class C fly ash, silica fume, glass powder, and dolostone. Pozzolanic reactivity was evaluated using seven different direct and indirect methods, including the Frattini test, strength activity index (SAI), ultrasound pulse velocity index (UPVI), thermogravimetric and differential thermal analyses (TG/DTA), calorimetry, electrical conductivity, and pH. Robust correlations and a ranking analysis were performed to evaluate the relationship and efficiency between various direct and indirect test methods. Results of the robust regression analyses showed that Frattini and TGA, SAI and electrical conductivity, SAI and calorimetry, and UPVI and calorimetry were well correlated, suggesting that these methods may be suitable alternatives to each other. According to the ranking method, electrical conductivity and calorimetry are the most rapid and efficient methods for the assessment of different pozzolans in comparison to other longer-duration test methods examined in this study.

Comparative deep learning studies for indirect tunnel monitoring with and without Fourier pre-processing

In the last decades, the majority of the existing infrastructure heritage is approaching the end of its nominal design life mainly due to aging, deterioration, and degradation phenomena, threatening the safety levels of these strategic routes of communications. For civil engineers and researchers devoted to assessing and monitoring the structural health (SHM) of existing structures, the demand for innovative indirect non-destructive testing (NDT) methods aided with artificial intelligence (AI) is progressively spreading. In the present study, the authors analyzed the exertion of various deep learning models in order to increase the productivity of classifying ground penetrating radar (GPR) images for SHM purposes, especially focusing on road tunnel linings evaluations. Specifically, the authors presented a comparative study employing two convolutional models, i.e. the ResNet-50 and the EfficientNet-B0, and a recent transformer model, i.e. the Vision Transformer (ViT). Precisely, the authors evaluated the effects of training the models with or without pre-processed data through the bi-dimensional Fourier transform. Despite the theoretical advantages envisaged by adopting this kind of pre-processing technique on GPR images, the best classification performances have been still manifested by the classifiers trained without the Fourier pre-processing.

Seroepidemiological investigation of Getah virus in the China-Myanmar border area from 2022-2023.

Getah Virus (GETV) is an RNA virus that is transmitted by mosquitoes and can cause disease or death in a variety of vertebrates. Its prevalence is increasingly severe in Asia. This study conducted a GETV epidemiological investigation on 1,300 bovine sera collected in the Honghe Prefecture of Yunnan Province on the China-Myanmar border from 2022 to 2023. The positive rate of GETV antibodies in bovine serum in Honghe Prefecture was determined to be 20.25% through indirect Enzyme-linked immunosorbent test (ELISA) methods. Using Real-time PCR methods to detect GETV RNA in bovine serum, the positive rate was 0.23% (3/1300), and viral nucleic acids were only detected in three bovine sera in Jianshui area in 2022. The YN2305 strain was successfully isolated from mouse neuroblastoma (N2a) cells and the complete gene sequence was obtained. All the above results indicate the existence of GETV infection in cattle in Honghe Prefecture, Yunnan Province. Homology and genetic evolution analysis found that the isolated strain has a high homology with the JL1808 strain isolated from cattle in 2018, with a nucleotide identity of 100%, and a nucleotide identity of 99.8% with the SD17-09 strain isolated from foxes in 2017. Compared with the nucleotides of 44 virus strains published in Genbank, YN2305 has multiple nucleotide site mutations in the structural gene E2 and non-structural gene NS. The nucleotide and amino acid identity of the E2 gene are 94.2-100% and 96.4-100%, respectively. Genetic evolution analysis found that this virus strain is most closely related to the bovine origin JL1808, and it is in gene group III with HuN1, Kochi-01, SD17-09, MI-110-C1, and MI-110-C2 strains that causes significant clinical symptoms in Chinese pig, fox and horse populations, belonging to the same evolutionary branch. This study determined the infection rate, genotype, and main prevalence areas of GETV in bovine sera in the China-Myanmar border area. Therefore, the epidemiological investigation of GETV infection in multiple animal hosts should be further expanded, and research on its pathogenicity and vectors should be carried out.

Comprehensive Review of Direct and Indirect Pozzolanic Reactivity Testing Methods

The production of portland cement is among the major contributors to greenhouse gas emissions that adversely affect the environment. Identifying sustainable materials to partially replace portland cement in concrete, such as pozzolanic materials, is crucial in addressing this issue. These materials mainly consist of silica and alumina that react with the available calcium hydroxide to form strength-bearing phases such as calcium silicate hydrates. Understanding the degree of pozzolanic reactivity of materials using efficient reactivity test methods is an important consideration. The paper thoroughly reviews the available literature related to direct and indirect pozzolanic reactivity test methods that have been utilized over the years. Direct methods quantify the amount of consumed calcium hydroxide, whereas indirect methods assess changes in the physical properties of the specimen due to pozzolanic reactions. The aim of this paper is to identify affordable, time-saving, and effective direct and indirect methods. Based on this study, the Frattini, electrical conductivity, and pH tests are considered the most time-efficient methods to assess pozzolanic materials. Electrical conductivity and pH tests are also easy to perform. In contrast, other methods are more time-consuming.

The needle penetration index for estimating the physico-mechanical properties of pyroclastic rocks

Preparation of suitable core specimens for physico-mechanical testing s not always possible, particularly for soft and clay-bearing rocks. Although several indirect test methods have been proposed to predict the properties of rocks, specimen preparation from soft rocks for some indirect tests is still difficult. For such cases, the needle penetration test has been developed. In this paper we present a study on the predictability of the physico-mechanical properties of pyroclastic rocks from the needle penetration index (NPI). The NPI, uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), density, and porosity tests were performed in the laboratory on specimens from ten different locations in Turkey. Correlations were established between the NPI values and the physico-mechanical properties. Strong correlations were observed between NPI and both UCS and BTS. General correlations were found between NPI and both density and porosity.

An Accurate Method for Measuring the Low-Temperature Coefficient of Resistors

The temperature coefficient of resistors is one of the key parameters to characterize the reliability of resistors. In precision circuit design, it is necessary to test and screen the key resistors and use the resistors with matching temperature coefficient values to ensure the accuracy and stability of circuit output. In this paper, aiming at how to accurately test the temperature coefficient value of low-temperature coefficient resistors, an indirect test method is proposed. The study adds a reference resistor into the test loop and tests the voltage values at both ends of the reference resistor. The tested resistor when the forward and reverse voltage sources are applied. The accurate resistance values of the tested resistor at different temperatures are obtained by calculation to calculate the temperature coefficient value of the resistor. The method can effectively reduce the measurement uncertainty of the test instrument and the potential thermoelectric influence generated in the test circuit. The measured results show that the measurement method proposed in this paper can obtain a more accurate and reliable resistor temperature coefficient.

Tensile and tear-type fracture toughness of gypsum material: Direct and indirect testing methods

In this context, four specimens, i.e. (i) circumferentially notched cylindrical torsion (CNCT), (ii) circumferentially notched cylindrical direct tension (CNCDT), (iii) edge notch disc bend (ENDB) and (iv) three-point bend beam (3PBB), were utilized to measure the modes I and III fracture toughness values of gypsum. While the CNCT specimen provides pure mode III loading in a direct manner, this pure mode condition is indirectly produced by the ENDB specimen. The ENDB specimen provided lower KIIIc and a non-coplanar (i.e. twisted) fracture surface compared with the CNCT specimen, which showed a planar mode III fracture surface. The ENDB specimen is also employed for conducting pure mode I (with different crack depths) and mixed mode I/III tests. KIc value was independent of the notch depth, and it was consistent with the RILEM and ASTM standard methods. But the mode III fracture results were highly sensitive to the notch depth. While the fracture resistance against mode III was significantly lower than that of mode I, the greater work of fracture under mode III was noticeable. ©2022 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Mechanical characterization and durability of earth blocks

With the growing awareness of environmental issues, raw earth construction in its various forms is experiencing a renewed interest. In fact, earth is a natural material that limits energy consumption and plays an important role in terms of humidity and temperature regulation. The demand for bio-based building materials and the addition of plant aggregates on earth building bricks is also increasing. This study focuses on the characterization of three unfired commercialized earth adobe bricks with different percentage of plant aggregates. The characterization of the constituents of the different adobe bricks has been first realized by conducting wet sieving tests, sedimentation, Atterberg limit and density tests. The performances of adobe bricks were then investigated and compared in terms of mechanical properties and durability considering freezing-thawing cycles and dry abrasion. The compressive strength is an important property but presents significant variations due to several influencing factors like source, proportion of constituent materials, curing condition, workmanship, in addition to testing procedure. Several specimens have been tested to quantify the compressive strength variability. In addition, as no consensus on the test design and limited data exists on the influence of specimen’s geometry and correlation between testing procedures and mechanical properties, a campaign of unconfined compressive tests has been conducted where several parameters have been varied such as specimen orientation and use of mortar or not. The tensile strength has been also measured with the indirect tensile test method. The effect of freezing thawing cycles was evaluated by subjecting the bricks to unconfined compressive tests after 3, 6, 9 and 12 freezing-thawing cycles. The results show a significant effect of the testing procedure on the compressive strength values. In addition, a decrease in the mechanical properties has been observed for adobe bricks exposed to freezing-thawing cycles.

The Effect of Salinity on the Chlorophyll Content of Wheat

Abiotic stress caused by salinity soil affects the development and plant growth, seed production and quality in a negative way. Salinity is an important factor influencing the quality of water. Saline stress causes negative reactions in plants both morphologically, biochemically and physiologically. The chlorophyll content is an important indicator of photosynthetic capacity of plants. Amount of chlorophyll is very influenced by nutrients reserve and by environment stress. Salinity in soil occurs as a result of the factors such as improper irrigation, lack of drainage, excessive accumulation of soluble salts. The research aims to study the behavior of an assortement of wheat varieties in terms of variability in salinity tolerance. To this end, an indirect test method for salinity tolerance, based on the determination of the influence of saline stress on chlorophyll accumulation, was pursued. Determination of chlorophyll content was performed at 7, 14, 21 days after saline stress induction. The duration of stress had the highest contribution (41.72%) to the variability of the chlorophyll content, followed by the saline (10.88%) and the varieties 7.63% respectively. At the level of the whole experiment it is observed that the chlorophyll content decreased progressively as saline stress prolongation. The change in the concentration from 200 to 240 Mm showed the highest influence on this property, materialized by a significant decrease in photosynthetic capacity. A good way to understand the plant photosynthetic regime is to determine the chlorophyll content as an indirect method. A selection criterion in screening for salt tolerance can be considered the physiological features that are positively associated with production under conditions of saline stress.

Evaluating the Radioactive Waste Produced per Patient by Radiopharmaceutical Sources and Measuring the Radioactive Contamination of Surfaces and Staff at the Bushehr Nuclear Medicine Department.

Nuclear medicine is an integral and developing field in diagnosing and treating diseases. Monitoring individuals' protection and radiation contamination in the workplace is vital for preserving working environments. This study aimed to monitor the nuclear medicine department's personnel, environment, and wastes to determine the level of occupational radiation and environmental pollution in Bushehr's nuclear medicine department. In this cross-sectional study, the initial activity of each radioisotope, radiopharmaceutical, and radioactive waste was measured using a "well counter" daily for three months. Three irradiators' absorbed doses were measured using a direct reading dosimeter. The contamination was determined using an indirect wipe test method on various surfaces. A Geiger Müller dosimeter was employed to examine personnel's hands, clothing, and footwear. The highest activity was observed in technetium waste (1118.31 mCi). Every irradiator received a lower absorption dose than the International Commission on Radiological Protection (ICRP) standard threshold. The majority of contamination was associated with the exercise test room (0.04 Bq/cm2) and its work surface (0.013 Bq/cm2), which were both below the threshold (0.5 Bq/cm2). Staff monitoring indicated that two nurses (10 and 11 individuals) had the highest contamination rate (23.7%). Daily assessment of the type, activity, and method of radiopharmaceutical administration to the patient is advantageous for waste management. Surface contamination monitoring can significantly contribute to the estimation of the level of radiation pollution in the environment.

The Interference of Monoclonal Anti-Cluster of Differentiation 47 on Transfusion Compatibility Testing

Hu5F9-G4 and AK117, novel cluster of differentiation 47 blockers, are used to treat solid tumors and hematoma. Because cluster of differentiation 47 is expressed on erythrocytes, treatment with monoclonal anti-cluster of differentiation 47 may interfere with the results of transfusion compatibility testing. This study analyzed the interference and treatment of Hu5F9-G4 and AK117 on transfusion compatibility testing. Saline and microcolumn gel methods were used to identify the blood types of the patients. To screen irregular antibodies, salt water, indirect antiglobulin test and polyamine methods were used. Various methods were used to identify antibodies, including saline, indirect antiglobulin test, polyamine and acid diffusion. This paper explores current methods for removing interference caused by monoclonal anti-cluster of differentiation 47. Hu5F9-G4 interferes with reverse typing of ABO blood groups, resulting in agglutination of all reagents used in antibody screening and identification. Patients’ erythrocyte acid dispersive fluid reacted positively with spectrum cells and erythrocytes treated with papain reacted positively with serum. In saline and coagulant amine media, AK117 did not agglutinate with screening cells, but it did with antihuman globulin media. Pre-transfusion testing can be interfered with by anti-cluster of differentiation 47 antibodies. To ensure safe blood transfusions, patients should have their blood type tested and antibodies screened before treatment.

A simple apparatus for tensile testing of rock

Measuring tensile strength of a quasi-brittle material such as rock is a challenging task. Indirect tensile testing methods such as the Brazilian and flexural tests rely on the assumption of linear elastic behavior, which is not valid close to the peak stress. The direct tensile testing method is independent of the constitutive response of the material and should provide more realistic data. Nevertheless, the test set up in direct tensile testing is time consuming and the results can depend on the applied boundary conditions. In this work, a new apparatus is introduced that can measure tensile strength of quasi-brittle materials and provide information regarding the crack opening behavior. The apparatus, which is an aluminum or steel beam with a cut-out and central notch, acts as both the loading fixture and load cell. The specimen is attached to the central part of the apparatus using an epoxy adhesive . Strain gages mounted on the two sides of the apparatus provide the necessary information about the tensile behavior of the specimen. The device is also capable of detecting and quantifying the intensity of asymmetric failure (crack growth) in the specimen, as identified by digital image correlation . The apparatus, its calibration, and some tests results are presented and discussed. • A new apparatus for tensile testing of rock is introduced. • Uniaxial tensile strength and critical crack opening of Charcoal granite are measured. • Comparison is made between the data collected using the new and conventional uniaxial tensile testing devices. • Digital image correlation is used to study the failure process.

Methods for evaluating the technical performance of reclaimed bricks

Reusing deconstructed materials and components can help to decrease the environmental burden of buildings. To safely reuse reclaimed items in new construction, methods are needed to reliably identify the essential technical properties of the deconstructed products. This paper looks at salvaged bricks and examines different indirect test methods to assess their properties. The explored test methods include visual observation, pitch of a sound, ultrasonic pulse velocity (UPV), and thin section. Reclaimed clay bricks and calcium silicate bricks were used in the research. They originated from four different buildings and from different kinds of structures. New bricks of the same kinds were also tested for reference and the properties were compared to the reclaimed ones. The assessed properties entail initial rate of water absorption, water absorption capacity, compressive strength, and freeze-thaw durability. The results show that it is possible to assess the deviation of properties and sort out exceptional bricks from a series with visual observation and pitch of a sound. The deviation of different properties can also be assessed with the help of UPV. A correlation was found between UPV and water absorption, compressive strength and freeze-thaw durability. Lower UPV values mean higher water absorption capacity and vice versa. Compressive strength of bricks is clearly lower when the UPV value is low and higher when the UPV is high. Bricks with lower UPV values (< 1.5 km/s) were also found to be freeze-thaw durable while those with higher UPV values (> 3.0 km/s) were found to be non-durable. Between the mentioned two values, the freeze-thaw durability varied. Thin section was only used to assess freeze-thaw durability and it was found to be unreliable as a method.

COMPARATIVE SERO-EVALUATION OF INFECTIOUS BURSAL DISEASE VIRUS VACCINE IN COMMERCIAL CHICKEN

The level of antibody titer against infectious bursal disease (IBD) in commercial chickens was determined using comparative sero evaluation through indirect ELISA test method. One hundred chickens of 1 day old were collected from a commercial hatchery and they were divided into two treatment groups named as ‘treatment group’ (flock 1) and ‘control group’ (flock 2). Serum samples of the flocks were collected randomly four times on day 1, 8, 16 and day 28. Serum samples were examined to quantify antibody titer using indirect ELISA method. A variation in the antibody titer was observed among chickens of two different flocks. Mean antibody titers were found at of 8686.4 and 9304.07 in day old chickens of flock 1 and flock 2 respectively. The mean antibody titers 7732 and 6375.15 were found in 8 day chickens of flock 1 and flock 2 respectively. The mean antibody titers 726.25 and 727.5835 were found in 16 days old chickens of flock 1 and flock 2 respectively. These chickens of treatment group (flock 1) were vaccinated with Gumboro live vaccine on days 16 and 21 while chickens of flock 2 were kept without vaccination. Blood samples collected on day 28 from both vaccinated and nonvaccination flocks were subjected to ELISA. The average antibody titers 2520.75 was found in 28 days old chickens of flock 1 after vaccination but the average antibody titers 110 was found in nonvaccinated flock 2. The day old samples contained high level of antibody titer on average and the level gradually declined and persisted up to 15-20 days. On day 28, the level of antibody reached much above minimum protection level in vaccinated chickens but the level was much below the protection level in nonvaccinated chickens. The results suggest that chicks should be vaccinated at around day 14, when the antibody level reaches to nearly minimum protection level.

Оценка технического состояния оснований, фундаментов и железобетонных колонн каркасного здания

The paper presents the results of assessing the technical condition of foundations, foundations and reinforced concrete columns, which are elements of building structures of a multi-storey frame public building. The results of the survey of foundation structures and the characteristics of the soil base are given. The physical and mechanical characteristics of soils were determined using samples taken from the pits during the survey. The results of visual examination and field measurements of foundations in control pits are given. The results of calculating the strength of concrete foundations and columns are given. The construction and correction of the calibration dependence of the indirect non-destructive testing method was carried out on the object using the method of separation with shearing. The results of verification calculations of foundations are considered. Defects and damages of foundations were revealed. The category of technical condition of bases and foundations is substantiated. Recommendations for the repair of foundations have been developed. The design and reinforcement of columns are considered. Identified defects and damage to the columns. the results of verification calculations of columns are given. The category of the technical condition of the columns is determined. Recommendations for the repair of columns have been developed. Defects and damages of reinforced concrete columns recorded in the list of defects and damages are investigated. The main conclusions are made based on the results of a survey of foundations and reinforced concrete columns of a multi-storey frame building.

A review on current direct and indirect testing methods as high-effective techniques in the evaluation of self-healing ability in concrete

As it has been using more than 100 years, concrete is a high compressive strength construction material and relatively easy to maintain and manage for buildings and infrastructures. However, with the increasing technical requirements of society for new constructions, various technologies have been developed to improve the strength, performance, and durability of concrete and overcome weaknesses, including the cracking phenomenon. The crack handling of concrete structures is a research hotspot and has caused long-term problems for the development of the engineering community. Currently, research on the world's self-healing concrete technology has been conducted in various ways. Also, promising progress has been made in different research approaches, but most are still in theoretical feasibility and laboratory-scale. Although there have been many reviews or mini-review papers published, aggregation, refinement, and criticism have never been redundant in light of the continued increase in the number of new publications. This paper has summarized the experimental research methods and results of different types of self-healing concrete in recent years and expounded the mechanism of its action, especially in the trend of using microorganisms for sustainable development. We also point out the outstanding issues and limitations in the studies and propose solutions.

Experimental Study on the Characterization of Orientation of Polyester Short Fibers in Rubber Composites by an X-ray Three-Dimensional Microscope.

Polyester-short-fiber-reinforced rubber composites have been detected by an X-ray three-dimensional microscope, and then the three-dimensional reconstruction of the image has been carried out to characterize the orientation of polyester short fibers in the composites for the first time. Based on the summary of three traditional methods and mechanisms of characterizing the orientation of polyester short fibers by the numerical parameter method, the direct test method, and the indirect test method, the method and mechanism of the X-ray three-dimensional microscope applied to the orientation characterization of polyester short fibers have been studied. The combination of the center point and threshold segmentation methods has been used to distinguish which fiber section belongs to the same fiber, and the identification of the whole short fiber in different slice images has been realized for the first time. Moreover, Avizo software has been used to realize the three-dimensional reconstruction of a polyester short fiber scanning image. The obtained data have been integrated and the orientation angle and orientation degree have been quantitatively characterized for the first time. This has filled the key technical problem of quantitative characterization of the orientation angle and orientation degree of polyester fibers. The image has been verified by 3Dmed software, and furthermore, the accuracy of the three-dimensional reconstruction results has been verified.

Retrospective Determination of the Prevelense of Anti-&lt;i&gt;Echinococcus granulosus&lt;/i&gt; Antibodies in Cystic Echinococcosis Pre-diagnosed Patients at Erciyes University Faculty of Medicine

Cystic echinococcosis (CE) is a parasitic disease that has been known for years in helminth diseases and it is important as human and animal health problem in many parts of the world and in our country due to economic losses. In this study, it was aimed to retrospectively evaluate the distribution of anti-E. granulosus-IgG antibodies in patients with pre-diagnosis of CE that referred to parasitology laboratory between January 2013-December 2018. Commercial kit was used for indirect hemaglutination (IHA), indirect fluorescent antibody test (IFAT) and Western blot (WB) methods using sera from patient samples was applied according to the kit proposal. In addition, patient materials for CAM, CSF and blood for which polymerase chain reaction (PCR)/QPCR tests were requested were examined. Sera of the patients who were tested with at least one of the IHA, IFAT and WB methods or a combination of these methods, and 443 cases out of 2.283 cases were found to be E. granulosus seropositive. It was determined that 369 (62.03%) of 443 positive patients were female and 330 (37.97%) were male patients. Among these patients, 87 patients whose IFAT and/or IHA tests were negative were found to have positive results with the WB method. IFAT or IHA test results of 13 patients with negative WB tests were found to be positive. Four patients were identified with both tests positive but WB test results negative. In addition, 36 of 72 patients who underwent PCR/QPCR tests were found to be positive. As a result of a six-year retrospective screening, 22% of the cases were found to be positive, and it was concluded that the prevalence of CE is high and the use of a single test may be insufficient in the diagnosis of CE, therefore, test combinations will increase the sensitivity and reliability in reaching the correct diagnosis.

Mycoplasma pneumoniae detections before and during the COVID-19 pandemic: results of a global survey, 2017 to 2021.

Background Mycoplasma pneumoniae respiratory infections are transmitted by aerosol and droplets in close contact.AimWe investigated global M. pneumoniae incidence after implementation of non-pharmaceutical interventions (NPIs) against COVID-19 in March 2020.MethodsWe surveyed M. pneumoniae detections from laboratories and surveillance systems (national or regional) across the world from 1 April 2020 to 31 March 2021 and compared them with cases from corresponding months between 2017 and 2020. Macrolide-resistant M. pneumoniae (MRMp) data were collected from 1 April 2017 to 31 March 2021.ResultsThirty-seven sites from 21 countries in Europe, Asia, America and Oceania submitted valid datasets (631,104 tests). Among the 30,617 M. pneumoniae detections, 62.39% were based on direct test methods (predominantly PCR), 34.24% on a combination of PCR and serology (no distinction between methods) and 3.37% on serology alone (only IgM considered). In all countries, M. pneumoniae incidence by direct test methods declined significantly after implementation of NPIs with a mean of 1.69% (SD ± 3.30) compared with 8.61% (SD ± 10.62) in previous years (p < 0.01). Detection rates decreased with direct but not with indirect test methods (serology) (–93.51% vs + 18.08%; p < 0.01). Direct detections remained low worldwide throughout April 2020 to March 2021 despite widely differing lockdown or school closure periods. Seven sites (Europe, Asia and America) reported MRMp detections in one of 22 investigated cases in April 2020 to March 2021 and 176 of 762 (23.10%) in previous years (p = 0.04).ConclusionsThis comprehensive collection of M. pneumoniae detections worldwide shows correlation between COVID-19 NPIs and significantly reduced detection numbers.