Effectiveness of heterologous third and fourth dose COVID-19 vaccine schedules for SARS-CoV-2 infection during delta and omicron predominance in Thailand: a test-negative, case-control study.

Background: The Coronavirus disease 2019 (COVID-19) pandemic has evolved quickly, with numerous waves of different variants of concern resulting in the need for countries to offer continued protection through booster vaccination. To ensure adequate vaccination coverage, Thailand has proactively adopted heterologous vaccination schedules. While randomised controlled trials have assessed homologous schedules in detail, limited data has been reported for heterologous vaccine effectiveness (VE). Methods: Utilising a unique active surveillance network established in Chiang Mai, Northern Thailand, we conducted a test-negative case control study to assess the VE of heterologous third and fourth dose schedules against SARS-CoV-2 infection among suspect-cases during Oct 1-Dec 31, 2021 (delta-predominant) and Feb 1-Apr 10, 2022 (omicron-predominant) periods. Findings: After a third dose, effectiveness against delta infection was high (adjusted VE 97%, 95% CI 94-99%) in comparison to moderate protection against omicron (adjusted VE 31%, 95% CI 26-36%). Good protection was observed after a fourth dose (adjusted VE 75%, 95% CI 71-80%). VE was consistent across age groups for both delta and omicron infection. The VE of third or fourth doses against omicron infection were equivalent for the three main vaccines used for boosting in Thailand, suggesting coverage, rather than vaccine type is a much stronger predictor of protection. Interpretation: Appropriately timed booster doses have a high probability of preventing COVID-19 infection with both delta and omicron variants. Our evidence supports the need for ongoing national efforts to increase population coverage of booster doses. Funding: This research was supported by the National Research Council of Thailand (NRCT) under The Smart Emergency Care Services Integration (SECSI) project to Faculty of Public Health Chiang Mai University.

Structural-based designed modular capsomere comprising HA1 for low-cost poultry influenza vaccination.

Highly pathogenic avian influenza (HPAI) viruses cause a severe and lethal infection in domestic birds. The increasing number of HPAI outbreaks has demonstrated the lack of capabilities to control the rapid spread of avian influenza. Poultry vaccination has been shown to not only reduce the virus spread in animals but also reduce the virus transmission to humans, preventing potential pandemic development. However, existing vaccine technologies cannot respond to a new virus outbreak rapidly and at a cost and scale that is commercially viable for poultry vaccination. Here, we developed modular capsomere, subunits of virus-like particle, as a low-cost poultry influenza vaccine. Modified murine polyomavirus (MuPyV) VP1 capsomere was used to present structural-based influenza Hemagglutinin (HA1) antigen. Six constructs of modular capsomeres presenting three truncated versions of HA1 and two constructs of modular capsomeres presenting non-modified HA1 have been generated. These modular capsomeres were successfully produced in stable forms using Escherichia coli, without the need for protein refolding. Based on ELISA, this adjuvanted modular capsomere (CaptHA1-3C) induced strong antibody response (almost 105endpoint titre) when administered into chickens, similar to titres obtained in the group administered with insect cell-based HA1 proteins. Chickens that received adjuvanted CaptHA1-3C followed by challenge with HPAI virus were fully protected. The results presented here indicate that this platform for bacterially-produced modular capsomere could potentially translate into a rapid-response and low-cost vaccine manufacturing technology suitable for poultry vaccination.

Detection of beta-thalassemia/hemoglobin E disease in samples which initially were diagnosed as homozygous hemoglobin E.

BACKGROUND: Differentiation of beta-thalassemia/HbE disease from homozygous HbE in samples containing HbA2/E > 75% and HbF < 15% is difficult. The aim of this study is to observe the possibility of using Hb typing and hematological parameters to identify both disorders. METHODS: Multiplex amplification refractory mutation system (MARMS)-PCR for beta-thalassemia codons 17 (A > T), 41/42 (-TCTT), 71/72 (+A), and IVSI-ntl (G > T) mutations and ARMS-PCR for HbE were performed in 67 samples that contained HbA2/E > 75% and HbF < 15%. RESULTS: Beta-thalassemia/HbE disease was identified in 10 of 67 (14.93%) samples. Levels of hemoglobin, hematocrit, and mean corpuscular volume (MCV) of beta-thalassemia/HbE disease were significantly lower than those of homozygous HbE whereas, levels of HbF were significantly higher. CONCLUSIONS: In places where the molecular analysis is not available, HbF > 5% in combination with MCV < 55 fL, hemoglobin < 100 g/L, and hematocrit < 0.30 L/L could be used for screening of beta-thalassemia/HbE disease.

Detection of coinherited Hb H-Constant Spring/Paksé disease and Hb E by capillary electrophoresis and high performance liquid chromatography.

A capillary electrophoresis (CE) method has been proven to be superior to a high performance liquid chromatography (HPLC) method in the detection of Hb H-Constant Spring/Paksé [Hb H (ß4) Hb CS or α142, Term→Gln, TAA>CAA (α2)]/Paksé [α142, Term→Tyr, TAA>TAT (α2)]. It also has the ability to quantify Hb Bart's (γ4). The aim of this study is to analyze the efficacy of the CE and HPLC in the detection of Hb H (ß4)-CS/Paksé-E [ß26(B8)Glu→Lys, GAG>AAG] disease. The laboratory results from July 2009 to July 2012 were reviewed at the Thalassemia Laboratory of the Associated Medical Sciences Clinical Service Center, Chiang-Mai University, Chiang-Mai, Thailand. The HPLC or CE method was used for the diagnosis of ß-thalassemia (ß-thal) and hemoglobinopathies, and molecular analysis was used for the diagnosis of α-thalassemia-1 (α-thal-1) Southeast Asian (SEA) and Thai type deletions, Hb CS and Hb Paksé. Hb H-CS-E was found in six samples and Hb H-Paksé-E was found in one sample, respectively. On the capillary electrophoregram, peaks of Hb Bart's and Hb CS/Paksé were observed in all samples with the mean levels at 2.4 and 1.0%, respectively. These peaks were also presented on the HPLC chromatogram. However, the Hb CS/Paksé level could be quantified in only three of these seven (43.0%) samples. Therefore, CE was proven to be superior to HPLC in the detection of Hb H-CS/Paksé-E disease, which will assist in diagnostic, counseling and prevention programs for these diseases.

Rapid identification of heterozygous and homozygous hemoglobin constant spring by SYTO9 with a high resolution melting analysis.

BACKGROUND: Gel-electrophoresis and ethidium bromide are not ideally suited to large scale analysis in clinical laboratories. METHODS: Amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) specific for Hb CS was performed in 10 blood samples from normal individuals and 61 samples containing a peak of Hb CS when analyzed by capillary electrophoresis. Heterozygosity of Hb CS was identified using SYTO9 and high resolution melting (HRM) analysis method. RESULTS: Specific peak heights of amplified fragments of wild type and Hb CS alleles were observed in the heterozygote. Only one peak height of amplified fragments of the wild type allele was observed in the normal individual while only one peak height of amplified fragments of Hb CS allele was observed in the homozygote. HRM analysis interpretation results were completely consistent with the interpretation results from gel-electrophoresis. CONCLUSIONS: SYTO9 HRM analysis may be used as an alternative for rapid diagnosis of heterozygosity of Hb CS.

Development of control material for hemoglobin analysis.

Background: There is no certified control material for hemoglobin analysis which has the hemoglobin (Hb)A(2)/E level as high as found in ?-thalassemia trait, HbE trait, ?-thalassemia/HbE disease and homozygote of HbE, the thalassemia types found frequently in the Southeast Asian population. The aim of this study was to prepare the lyophilized hemoglobin control materials for hemoglobin analysis. Methods: Washed and dialysed erythrocytes of normal individuals and patients with ?-thalassemia trait, HbE trait, ?-thalassemia/HbE disease, homozygous HbE were lysed in 5% sucrose solution. The lyophilized hemoglobin control materials were prepared by using a freeze-drying (lyophilization) method. The high performance liquid chromatography (HPLC) analysis of lyophilized hemoglobin was performed after storing at ?20?C for 1, 15 and 30?days and for 3?months. Results: The chromatograms of lyophilized hemoglobin control materials showed similar patterns and similar levels of HbA, HbA(2)/E and HbF when compared with equivalent fresh whole blood. Moreover, the lyophilized hemoglobin presented a good correlation coefficient (r>0.990) of relationships between HPLC, low pressure liquid chromatography (LPLC) and capillary electrophoresis (CE) methods. Conclusions: The lyophilized hemoglobin could be developed and used as control materials for hemoglobin analysis.

Comparison between capillary electrophoresis and high performance liquid chromatography for detection and quantification of Hb constant spring [Hb CS; α142, Term→Gln (TAA>CAA IN α2)].

Hb Constant Spring [Hb CS; α142, Term→Gln (TAA>CAA in α2)] is often missed by routine laboratory testing since its mRNA as well as gene product are unstable and presented at a low level in peripheral blood. This study aimed to analyze the efficacy of capillary electrophoresis (CE) and high performance liquid chromatography (HPLC) for detecting and quantifying Hb CS in 19 heterozygotes and 14 homozygotes with Hb CS as well as 10 Hb H-CS disease subjects who were detected by molecular analysis. In the CE electrophoregram, Hb CS was seen at zone 2 and was observed in all samples, while the chromatogram of Hb CS peaks was found in 26.32% heterozygotes, 42.86% homozygotes and 90% Hb H-CS disease subjects, respectively. In addition, the Hb CS levels in each group of subjects quantified by CE were significantly higher than those quantified by HPLC. Based on the CE method, the lowest Hb CS level was found in the heterozygotes, whereas the highest level was found in the Hb H-CS disease patients. Therefore, the CE method was superior to the HPLC method for detecting Hb CS. Furthermore, the level of Hb CS quantified by CE proved useful in screening heterozygotes and homozygotes with Hb CS as well as Hb H-CS disease.

Comparative diagnosis of malaria infections by microscopy, nested PCR, and LAMP in northern Thailand.

Three methods, microscopy, nested polymerase chain reaction (nPCR), and loop-mediated isothermal amplification (LAMP) have been applied for malaria diagnosis in 105 human blood samples collected in Northern Thailand. Only Plasmodium falciparum and Plasmodium vivax infections were detected. A total number of 57 positives (54%) could be detected for P. falciparum and 25 (24%) for P. vivax when all samples that were positive in any of the three methods are counted together. The nPCR was used as a reference standard for comparison with the other methods, microscopy and LAMP. The sensitivity of LAMP for P. falciparum was 100%. All nPCR-negative samples for P. falciparum were also negative by both microscopy and LAMP (specificity, 100%). For diagnosis of P. vivax, microscopy detected 15 of 23 nPCR-positive samples (sensitivity, 65%). LAMP detected 22 of 23 nPCR-positives (sensitivity, 96%). Among the 82 nPCR-negative samples microscopy detected two samples (specificity, 98%). All 82 nPCR-negative were also negative by the LAMP method (specificity, 100%). Both Plasmodium genus- and species-specific LAMP primer sets yielded the same results in all samples. There were no significant differences in the prevalence detected by each method. We assume that LAMP was as reliable as nPCR and more reliable than microscopy in the detection of Plasmodium DNA tested in the examined Thai field blood samples. This study further validates LAMP as an alternative molecular diagnostic tool, which can be used in the diagnosis of early infections of malaria cases and together with nPCR can also be used as supplementary methods for clinical and epidemiological use.

Circulation of dengue serotypes in five provinces of northern Thailand during 2002-2006.

disease prevalent in all provinces of Thailand. This study was to determine the circulating dengue serotypes by reverse transcription polymerase chain reaction (RT-PCR). A total of 1116 seropositive acute samples were analysed from DF/DHF patients in five provinces of northern Thailand (Chiangmai, Lampang, Lamphun, Mae Hong Son and Phrae) during the period January 2002 to December 2006. Five hundred and fifty-nine samples were found positive, of which 47.2%, 30.6%, 18.4% and 3.8% were affected with DENV-2, DENV-1, DENV-4 and DENV-3 respectively. From 2002 to 2005, the predominant dengue serotype was DENV-2, whereas DENV-1 was predominant in 2006. There was an apparent increase in the percentage of DENV-4 from 2005 to 2006. Our results indicated that all four dengue serotypes were circulating in this region and the annual change of predominant serotypes was the cause of the severity of the disease.