Effective and safe transfer of maternal antibodies persisting two months postpartum following maternal immunization with different doses of recombinant pertussis-containing vaccines.

INTRODUCTION: Recombinant acellular pertussis (ap) vaccines containing genetically inactivated pertussis toxin (PTgen) and filamentous hemagglutinin (FHA) with or without tetanus (TT) and diphtheria (DT) vaccines (Td) were found safe and immunogenic in non-pregnant and pregnant women. We report here maternal antibody transfer and safety data in mothers and neonates. METHODS: This is the follow up of a phase 2 trial in 2019 among 400 pregnant women who randomly received one dose of recombinant pertussis-only vaccine containing 1 µg PTgen and 1 µg FHA (ap1gen), or Td combined with ap1gen (Tdap1gen), or with 2 µg PTgen and 5 µg FHA (Tdap2gen), or with 5 µg PTgen and 5 µg FHA (TdaP5gen, Boostagen®, BioNet, Thailand) or chemically-inactivated acellular pertussis comparator (Tdap8chem, Boostrix™, GSK, Belgium), either in the second or third trimester of gestation. IgG against PT, FHA, TT and DT were assessed by ELISA, PT-neutralizing antibodies (PTNA) by Chinese Hamster Ovary cell assay and safety outcomes at delivery in mothers and at birth. RESULTS: Anti-PT and anti-FHA geometric mean concentration (GMC) ratio between infants at birth and mothers at delivery was above 1 in all groups. PT GMC in infants at birth were ≥30 IU/mL in all groups with the highest titers in infants found in TdaP5gen group at birth (118.8 [95% CI 93.9-150.4]). At 2 months, PT GMC ratio to Tdap8chem (98.75% CI) was significantly higher for TdaP5gen (2.6 [1.7-4.0]) and comparable for other recombinant vaccines. No difference in PTNA titers at birth was observed between all groups nor between time of vaccination. Adverse events were comparable in all vaccine groups. CONCLUSIONS: BioNet licensed (TdaP5gen and Tdap2gen) and candidate vaccines (Tdap1gen and ap1gen) when given to pregnant women in the second or third trimester of gestation are safe and have induced passive pertussis immunity to infants.

Immunogenicity of BNT162b2 in children 6 months to under 5 years of age with previous SARS-CoV-2 infection, in the era of Omicron predominance.

Background: Children 6 months to < 5 years old are recommended to receive 3-dose regimen of BNT162b2. Children previously infected with Omicron variant of SARS-CoV-2 develop immunity from natural infection, therefore may require fewer doses of vaccine. Objective: To compare immunogenicity of 1- or 2-dose BNT162b2 in healthy children post COVID-19 with 3-dose BNT162b2 in COVID-naïve children. Methods: Children aged 6 months to < 5 years who developed COVID-19 during the Omicron-predominant period were enrolled; Group A 3-6 months(N = 40) and Group B > 6 months(N = 40) prior to vaccination. Participants in Group A and B received 2-dose BNT162b2 intramuscularly 1 month apart. COVID-naïve children were enrolled as a control group (N = 40) and received 3-dose BNT162b2 at month 0,1,3. Neutralizing antibody against Omicron variant(BA.2.75 and BA.4/5) was determined by pseudovirus assays(pVNT) as reported by neutralization dilution for 50%inhibition (ID50) at 28 days after the 1st and 2nd dose. Results: From October-November 2022, 120 children with a median age of 2.8 years (IQR 1.6-4.0) were enrolled. The median duration since COVID-19 to vaccination was 4.4 months(IQR 3.8-5.4) in Group A and 7.9 months(7.0-8.5) in Group B. In Group A, the geometric means(GMs) of pVNT-BA.2.75 ID50 were 553 (95%CI 338-906) and 753(516-1098) after 1 and 2 doses, respectively, and the GMs of pVNT-BA.4/5 ID50 were 1936(1402-2673) and 1885(1414-2512), respectively. In Group B, the GMs of pVNT-BA.2.75 ID50 were 1383(1100-1742) and 1419 (1104-1823), and the GMs of pVNT-BA.4/5 ID50 were 2627(2048-3367) and 2056(1546-2735), respectively. Meanwhile in COVID-naïve group, the GMs of pVNT-BA.2.75 and pVNT-BA.4/5 ID50 were 158(98-255) and 59(31-114) after the 3rd dose, respectively. The geometric mean ratio(GMR) of pVNT-BA.2.75 ID50 after 1 dose in Group A and B compared with after 3 doses in COVID-naïve group were 3.50 (1.93-6.34) and 8.74 (4.79-15.95), respectively. The GMR of pVNT-BA.2.75 ID50 after 1 dose in Group B compared with Group A was 2.50 (1.45-4.31). Conclusions: Children previously infected with SARS-CoV-2 Omicron variant, developed robust neutralizing antibody response against Omicron variant after single-dose BNT162b2. Children with an interval of > 6 months since COVID-19 infection developed higher neutralizing antibody response compared to those with a 3-to-6-month interval.

Outcomes among Thai children with risk conditions hospitalized for pneumococcal disease (invasive or non-bacteraemic pneumonia): A multi-centre, observational study.

Objective: To describe the risk condition status and clinical outcomes among Thai children hospitalized with pneumococcal disease. Methods: In this retrospective analysis, children with invasive pneumococcal disease (IPD) or x-ray-confirmed non-bacteraemic pneumococcal pneumonia (NBPP) were identified from nine hospitals in Thailand between 2010 and 2019. Data on risk factors and outcomes were extracted from medical records. Results: In total, 413 cases were identified: 319 IPD and 94 NBPP. Overall, 133 (32.2%) patients were admitted to intensive care units and 11/406 (2.7%) died. Twenty-seven percent of IPD cases had at-risk conditions and 15% had high-risk conditions. Most IPD cases (32.9%) occurred in children aged 2-4 years, and most NBPP cases (28.7%) occurred in infants aged 0-11 months. Of 51 Streptococcus pneumoniae isolates collected, 41 (80%) were pneumococcal 13-valent conjugate vaccine serotypes. Only 5.1% of children had received a pneumococcal vaccine. Conclusions: Most children with IPD and NBPP did not have high-risk or at-risk conditions, while 42% had at-risk or high-risk conditions for pneumococcal disease. Very few children in the cohort had received any type of pneumococcal vaccine. Increasing the availability of pneumococcal conjugate vaccines should be considered to reduce the burden of pneumococcal disease among children in Thailand.

A phase 2 randomized controlled dose-ranging trial of recombinant pertussis booster vaccines containing genetically inactivated pertussis toxin in pregnant women.

INTRODUCTION: Despite a decrease in infections caused by Bordetella pertussis due to COVID-19 pandemic, booster vaccination of pregnant women is still recommended to protect newborns. Highly immunogenic vaccines containing genetically inactivated pertussis toxin (PTgen) and filamentous hemagglutinin (FHA) may generate comparable anti-PT antibody concentrations, even at lower doses, to chemically inactivated acellular pertussis vaccines (Tdapchem) shown effective for maternal immunization. METHODS: This phase 2 randomized, observer-blind, active-controlled non-inferiority trial was conducted in healthy Thai pregnant women randomly assigned to receive one dose of low-dose recombinant pertussis-only vaccine containing 1 µg PTgen and 1 µg FHA (ap1gen), or tetanus, reduced-dose diphtheria combined with ap1gen (Tdap1gen), or combined with 2 µg PTgen and 5 µg FHA (Tdap2gen), or with 5 µg PTgen and 5 µg FHA (TdaP5gen, Boostagen®) or comparator containing 8 µg of chemically inactivated pertussis toxoid, 8 µg FHA, and 2.5 µg pertactin (Boostrix™, Tdap8chem). Blood was collected at Day 0 and Day 28 post-vaccination. The non-inferiority of the study vaccines was assessed based on anti-PT IgG antibody levels on Day 28 pooled with results from a similarly structured previous trial in non-pregnant women. RESULTS: 400 healthy pregnant women received one dose of vaccine. Combined with data from 250 non-pregnant women, all study vaccines containing PTgen were non-inferior to comparator vaccine (Tdap8chem). Both ap1gen and TdaP5gen vaccines could be considered to have superior immunogenicity to Tdap8chem. Local and systemic solicited reactions were similar among all vaccine groups. CONCLUSIONS: Vaccine formulations containing PTgen were safe and immunogenic in pregnant women. The ap1gen vaccine, with the lowest cost and reactogenicity, may be suitable for use in pregnant women when diphtheria and tetanus toxoids are not needed. This study is registered in the Thai Clinical Trial Registry (www. CLINICALTRIALS: in.th), number TCTR20180725004.

Good performance of syphilis rapid diagnostic test kits among young key populations in Thailand.

BACKGROUND: The prevalence of syphilis is increasing among adolescents and young adults (AYAs) globally. Use of syphilis rapid diagnostic treponemal tests (RDTs) may improve test coverage and same-day treatment. This study aims to determine sensitivity and specificity of two syphilis RDTs. METHODS: A cross-sectional study was conducted in men who have sex with men and transgender women aged 15-24 years attending a sexual health clinic in Bangkok. Syphilis RDTs used were Determine Syphilis TP and Bioline Syphilis 3.0, using whole blood from finger pricks and venipuncture. Treponemal pallidum electrochemiluminescence assay was used as standard reference. RESULTS: From February to July 2022, 200 AYAs with a mean age 21.1 (SD2.1) years were enrolled, including 50 (25.0%) living with HIV. Prevalence of syphilis was 10.5% (95%CI 6.6-15.6), which was higher among AYAs living with HIV (22.0%) compared with AYAs unaffected by HIV (6.7%). Sensitivities of Determine Syphilis TP and Bioline Syphilis 3.0 were 85.7% (95%CI 63.7-97.0) and 66.7% (95%CI 43.0-85.4), respectively. Specificity of both RDTs was 100% (95%CI 98.0-100.0). Performance of RDTs was similar for both specimens. CONCLUSIONS: Syphilis RDTs have high sensitivity and specificity in diagnosing syphilis. It should be considered for use in sexual health clinics with high syphilis prevalence to initiate treatment promptly.

Long COVID and Hybrid Immunity among Children and Adolescents Post-Delta Variant Infection in Thailand.

This study aimed to assess long COVID, and describe immunogenicity against Omicron variants following BNT162b2 vaccination. A prospective cohort study was conducted among children (aged 5-11) and adolescents (aged 12-17) who had SARS-CoV-2 infection from July to December 2021 (Delta predominant period). Long COVID symptoms were assessed by questionnaires at 3 months after infection. Immunogenicity was evaluated by using a surrogate virus-neutralizing antibody test (sVNT) against the Omicron variant. We enrolled 97 children and 57 adolescents. At 3 months, 30 children (31%) and 34 adolescents (60%) reported at least one long COVID symptom, with respiratory symptoms prevailing (25% children and 32% adolescents). The median time from infection to vaccination was 3 months in adolescents and 7 months in children. At 1 month following vaccination, in children who received one-dose and two-dose BNT162b2 vaccines, the median (IQR) sVNT against Omicron was 86.2% inhibition (71.1-91.8) and 79.2% inhibition (61.5-88.9), respectively (p = 0.26). Among adolescents who received one-dose and two-dose BNT162b2 vaccines, the median (IQR) sVNT against Omicron was 64.4% inhibition (46.8-88.8) and 68.8% inhibition (65.0-91.2) (p = 0.64). Adolescents had a higher prevalence of long COVID than children. Immunogenicity against the Omicron variant after vaccination was high and did not vary between one or two doses of the vaccine in either children or adolescents.

Point prevalence survey of antibiotic use among hospitalized patients across 41 hospitals in Thailand.

Objectives: To describe the antibiotic use among hospitalized patients in Thailand. Methods: A standardized cross-sectional point prevalence survey (PPS) modified from the WHO PPS protocol was conducted in 41 selected hospitals in Thailand. All inpatients who received an antibiotic at 9 a.m. on the survey date were enrolled. The total number of inpatients on that day was the denominator. Results: Between March and May 2021, a total of 8958 inpatients were enumerated; 4745 inpatients received antibiotics on the day of the survey and there were 6619 prescriptions of antibiotics. The prevalence of antibiotic use was 53.0% (95% CI 51.1%-54.0%), ranging from 14.3% to 73.4%. The antibiotic use was highest among adults aged >65 years (57.1%; 95% CI 55.3%-58.9%). From 6619 antibiotics prescribed, 68.6% were used to treat infection, 26.7% for prophylaxis and 4.7% for other or unknown indications. Overall, the top three commonly used antibiotics were third-generation cephalosporins (1993; 30.1%), followed by first-generation cephalosporins (737; 11.1%) and carbapenems (703; 10.6%). The most frequently used antibiotics for community-acquired infections were third-generation cephalosporins (36.8%), followed by ß-lactam/ß-lactamase inhibitors (11.8%) and carbapenems (11.3%) whereas for the patients with hospital-acquired infections, the most common antibiotics used were carbapenems (32.7%), followed by ß-lactam/ß-lactamase inhibitors (15.7%), third-generation cephalosporins (11.7%) and colistin (11.7%). The first-generation cephalosporins were the most commonly used antibiotics (37.7%) for surgical prophylaxis. Seventy percent of the patients received surgical prophylaxis for more than 1 day post surgery. Conclusions: The prevalence of antibiotic use among hospitalized patients in Thailand is high and one-quarter of these antibiotics were used for prophylaxis. The majority of surgical prophylaxis was inappropriately used for a long duration post operation. Therefore, it is recommended that local guidelines should be developed and implemented.

Neurological complications associated with influenza in hospitalized children.

BACKGROUND: Influenza is a known respiratory and potential neurotropic virus. This study aimed to determine the prevalence and outcomes of influenza-related neurological complications among hospitalized children. METHODS: All medical records of hospitalized children aged <18 years old diagnosed with influenza at a tertiary care hospital in Bangkok were retrospectively reviewed. Influenza infection was confirmed by rapid antigen or reverse transcription polymerase chain reaction tests. Neurological characteristics and clinical outcomes were analyzed using the Pediatric Cerebral Performance Category Scale. RESULTS: From 2013 to 2018, 397 hospitalized children with a median age of 3.7 years (interquartile range [IQR]: 1.6-6.9) were included. The prevalence of neurological complications, including seizure or acute encephalopathy, was 16.9% (95% confidence interval [CI]: 13.3-20.9). Influenza A and B were identified in 73.1% and 26.9% of the patients, respectively. Among 39 (58.2%) acute symptomatic seizure cases, 25 (37.3%) children had simple febrile seizures, 7 (10.4%) had repetitive seizures, and 7 (10.4%) had provoked seizures with pre-existing epilepsy. For 28 (41.8%) encephalopathy cases, the clinical courses were benign in 20 (29.9%) cases and severe in 8 (11.9%) cases. Ten (14.9%) children needed intensive care monitoring, and 62 (93.5%) fully recovered to their baselines at hospital discharge. Predisposing factors to the neurological complications included a history of febrile seizure (adjusted odds ratio [aOR]: 20.3; 95% CI: 6.6-63.0), pre-existing epilepsy (aOR: 3.6; 95% CI: 1.3-10.2), and a history of other neurological disorders (aOR: 3.5; 95% CI: 1.2-10.2). CONCLUSIONS: One fifth of hospitalized children with influenza had neurological complications with a favorable outcome. Children with pre-existing neurological conditions were at higher risk for developing neurological complications.

Case Report: Simple Nodular Cutaneous Leishmaniasis Caused by Autochthonous Leishmania (Mundinia) orientalis in an 18-Month-Old Girl: The First Pediatric Case in Thailand and Literature Review.

We report an autochthonous case of simple, localized cutaneous leishmaniasis in a healthy 18-month-old girl from southern Thailand. The patient presented with a solitary chronic cutaneous nodular lesion on her left cheek for approximately 1 year. Histopathological dissection of the cheek skin biopsy demonstrated remarkably nodular and interstitial infiltrates of lymphocytes and histiocytes full of intracellular oval-shaped amastigotes, consistent with cutaneous leishmaniasis. The Leishmania promastigotes were also cultured successfully from the lesion biopsy and were designated with the WHO code MHOM/TH/2021/CULE5. Using internal transcribed spacer 1-specific polymerase chain reaction, the parasite DNA was demonstrated in both saliva and lesion biopsy. Based on the BLASTn and phylogenetic analysis, the parasite was identified as Leishmania orientalis, clustered in the Mundinia subgenus. The patient responded well to a 6-week course of oral itraconazole, without recurrence. To our knowledge, this is the fourth case of autochthonous leishmaniasis resulting from L. orientalis and the youngest patient of leishmaniasis ever reported in Thailand. More importantly, we also demonstrate the clinical course of the lesion according to the timeline before and after treatment, which can help physicians better understand and provide an accurate diagnosis with appropriate treatment of this emerging parasitic disease.

Pregnancy and birth outcomes among young women living with perinatally acquired HIV in Thailand and Vietnam.

We conducted a retrospective cohort study of pregnancy and infant outcomes in 670 adolescents and young adult women with perinatally acquired HIV (AYAPHIV), aged 15-24 years, in Thailand and Vietnam. Between January 2013 and December 2018, there were 52 pregnancies, for an incidence of 2.49 (95% CI 1.90-3.27) per 100 person-years. The median age at pregnancy was 17.7 years (IQR 16.8-18.9). Pregnant AYAPHIV had been on cART for a lifetime median of 9.8 years (IQR 7.3-12.4). At the time of conception, the median CD4 was 521 cells/mm3 (IQR 213-760), and 76% had HIV RNA ≤400 copies/ml. Of the 51 pregnancies with available outcomes, 90% resulted in live singleton births at a median gestational age of 38 weeks (IQR 37-39); 77% of mothers (n = 27/35) had HIV RNA ≤400 copies/ml at delivery. Among infants with available data, 50% (n = 21/42) were male and 29% (n = 12/42) were reported to be low birthweight (<2,500gm); none (n = 0/41) were breastfed. One infant was diagnosed with HIV. Our findings emphasize that efforts to strengthen reproductive health education, including contraception, pregnancy-related psychosocial support services, and prevention of vertical HIV transmission interventions, in our region are needed for adolescents with perinatally acquired HIV as they transition to young adults.

Incidence of healthcare-associated urinary tract infections in Thai children.

BACKGROUND: Urinary tract infection is one of the commonest types of healthcare-associated infections. There are currently limited data regarding the incidence and characteristics of healthcare-associated urinary tract infections (HA-UTIs) in children. This study was conducted to determine the incidence of HA-UTIs and their characteristics and associated risk factors. METHODS: A case-control study was performed from 2016 to 2020 on children under 15 years old who were diagnosed with HA-UTI. Patients who had HA-UTI were compared with non-UTI patients. The incidence rate of HA-UTIs was calculated and reported as events per 1000 patient days. Potential associated risk factors were analyzed using multivariate logistic regression. RESULTS: Eighty cases and 80 controls were included in the study. The incidence of HA-UTIs was 0.32 events per 1000 patient days. The median time to UTI was 18 days. The most common causative organism was Escherichia coli (43.2%) and the rates of third-generation cephalosporin resistance and carbapenem resistance were 75.6% and 4.9%, respectively. Admission longer than 7 days (OR = 21.61, 95% CI: 6.30-74.11; p < 0.001), neurogenic bladder (OR = 26.24, 95% CI: 3.77-182.87; p < 0.001), mechanical ventilation (OR = 3.60, 95% CI: 1.23-10.54; p = 0.019), and immunosuppressants (OR = 2.59; 95% CI: 1.01-6.60; p = 0.047) were the risk factors significantly associated with HA-UTIs. CONCLUSIONS: The incidence of HA-UTIs was low in this single-center experience. Identifying patients with the risk factor is imperative for preventing the development of HA-UTIs.

Social Network Strategy to Promote HIV Testing and Linkage to HIV Services among Young men who Have sex with men and Transgender Women in Thailand.

Background: Social network strategies (SNS) assumes that people in the same social share similar HIV risk. Methods: This study evaluated SNS to promote HIV testing of young men who have sex with men (YMSM) and transgender women (YTGW) aged 15-24 years. "Recruiters" referred their 'network members' (NMs) to clinic. NMs were provided HIV testing. Proportions of first-time HIV testers and number of NMs were analyzed. Results: Between April 2021 to March 2022, 83 recruiters referred 202 NMs. Median age of NMs was 19 years (IQR 17-20), 62% were YMSM. One-hundred-and-twenty-four NMs (61%) were first-time HIV testers. YTGW recruited more NMs per recruiter (5.4 vs 1.4, p = 0.002). HIV prevalence was 3.0% (95% CI 1.1-6.4). Thirty-one-point-three percent of NMs at HIV risk initiated oral HIV preexposure prophylaxis. Conclusions: SNS is a good strategy to reach adolescents at risk of HIV infection. More than half of NMs were first-time HIV testers.

Immunogenicity to SARS-CoV-2 Omicron variant among school-aged children with 2-dose of inactivated SARS-CoV-2 vaccines followed by BNT162b2 booster.

Background: A primary series of 2-dose SARS-CoV-2 vaccines based on an ancestral strain generate inadequate neutralizing antibodies against the SARS-CoV-2 Omicron variant. This study aimed to describe the immune response from giving healthy school-aged children who previously received 2 inactivated vaccines an mRNA BNT162b2 booster. Methods: Healthy children aged 5-11 years who received 2 doses of CoronaVac or Covilo were enrolled and received 10 µg BNT162b2 intramuscularly. Neutralizing antibody against Omicron variant was measured at pre-booster and 14-21 days post-booster by surrogate virus neutralization test (sVNT, %inhibition) and pseudovirus neutralization test (pVNT, ID50). Antibody responses were compared with a parallel cohort of children who received 2 doses of BNT162b2 3 weeks apart. Results: From April to May 2022, 59 children with a mean age (SD) of 8.5 years (1.7) were enrolled: 20 CoronaVac and 39 Covilo recipients. The median interval from the primary series was 49 days (IQR 33-51). After booster, the geometric means (GMs) of sVNT and pVNT were 72.2 %inhibition (95 %CI 67.2-77.6) and 499 (95 %CI 399-624), respectively. The proportion of children with sVNT against Omicron strain ≥68 %inhibition increased from none to 70.2 %. The geometric mean ratio (GMR) of sVNT and pVNT compared with a parallel cohort were 4.3 and 12.2, respectively. The GMR of sVNT and pVNT between children who received booster dose at >6-week interval were 1.2 (95 %CI 1.1-1.3). and 1.8 (95 %CI 1.2-2.7) compared with 4-6 weeks interval. Conclusion: A regimen of 2-dose of inactivated vaccine followed by BNT162b2 booster dose elicited high neutralizing antibody against the Omicron variants in healthy school-aged children.

Heterologous Prime-boost of SARS-CoV-2 inactivated vaccine and mRNA BNT162b2 among Healthy Thai Adolescents.

Background: Heterologous prime-boost SARS-CoV-2 vaccination is a widely accepted strategy during the COVID-19 pandemic, which generated a superior immune response than homologous vaccination strategy. Objective: To describe immunogenicity of heterologous prime-boost vaccination with inactivated vaccine, CoronaVac, followed by BNT162b2 and 5-month booster dose with BNT162b2 in healthy Thai adolescents. Methods: Adolescents aged 12-18 years were randomized 1:1:1:1 to receive CoronaVac (SV) followed by BNT162b2 (PZ) 30 or 20 µg at either 3- or 6-week interval (SV3w/PZ30µg, SV3w/PZ20µg, SV6w/PZ30µg or SV6w/PZ20µg). During the Omicron-predominant period, participants were offered a BNT162b2 booster dose 30, 15, or 10 µg. Immunogenicity was determined using IgG antibody against spike-receptor-binding domain of wild type(anti-S-RBD IgG) and surrogate virus neutralization test(sVNT) against Delta variant at 14 days and 5 months after the 2nd dose. Neutralization tests(sVNT and pseudovirus neutralization test; pVNT) against Omicron strain were tested pre- and 14 days post-booster dose. Results: In October 2021, 76 adolescents with a median age of 14.3 years (IQR 12.7-16.0) were enrolled: 20 in SV3w/PZ30µg; 17 in SV3w/PZ20µg; 20 in SV6w/PZ30µg; 19 in SV6w/PZ20µg. At day 14, the geometric mean(GM) of anti-S-RBD IgG in SV3w/PZ30µg was 4713 (95 %CI 4127-5382) binding-antibody unit (BAU)/ml, while geometric mean ratio(GMR) was 1.28 (1.09-1.51) in SV6w/PZ30µg. The GMs of sVNT against Delta variants at day 14 among participants in SV3w/PZ30µg and SV6wk/PZ30µg arm were 95.3 % and 99.7 %inhibition, respectively. At 5 months, GMs of sVNT against Delta variants in SV3w/PZ30µg were significantly declined to 47.8 % but remained at 89.0 % inhibition among SV6w/PZ30µg arm. In April 2022, 52 adolescents received a BNT162b2 booster dose. Proportion of participants with sVNT against Omicron strain > 80 %inhibition was significantly increased from 3.8 % pre-booster to 67 % post-booster. Proportion of participants with pVNT ID50 > 185 was 42 % at 14 days post 2nd dose and 88 % post booster, respectively. Conclusions: Heterologous prime-boost vaccination with CoronaVac followed by BNT162b2 induced high neutralizing titer against SARS-CoV-2 Delta strain. After 5-month interval, booster with BNT162b2 induced high neutralizing titer against Omicron strain.Thai Clinical Trials Registry (thaiclinicaltrials.org): TCTR20210923012.

Low Measles Seropositivity Rate among Thai Adolescents in the Thai National Immunization Program.

To achieve the goal of measles elimination, herd immunity with 95% seroprotection in the community is required. This study aimed to describe the measles seropositivity rate among Thai children and adolescents. A cross-sectional study was conducted among children aged 3−18 years in Bangkok and its suburbs. Measles IgG antibodies were measured using a EUROIMMUN enzyme-linked immunosorbent assay kit. Seropositivity is defined as a measles IgG titer of ≥200 IU/L, due to a correlation with a >85% positive rate with a plaque reduction neutralizing titer of >120. Factors associated with seropositivity were analyzed using logistic regression analysis. From May to July 2020, 570 children with a median (IQR) age of 11.7 (9.4−14.8) years were enrolled. The geometric mean titer (GMT) of anti-measles IgG was 281 IU/L (95% CI; 257−306). The proportion of children with seropositivity was inversely correlated with age; 3−5 years 85.3%, 6−9 years 72.5%, 10−14 years 50.7%, and 15−18 years 56.3%. Adolescents aged 10−18 years had a lower measles seropositivity rate compared with young children; aOR 0.29 (95% CI 0.17−0.48). Only half of the adolescents who received two doses of measles-containing vaccine maintained measles IgG above the seropositive level. A measles booster dose for young adults may be needed to achieve the measles elimination goal.

Immunogenicity of BNT162b2 Vaccination against SARS-CoV-2 Omicron Variant and Attitudes toward a COVID-19 Booster Dose among Healthy Thai Adolescents.

Despite the BNT162b2 vaccination coverage, rapid transmission of Omicron SARS-CoV-2 has occurred, which is suspected to be due to the immune escape of the variant or waning vaccine efficacy of multiple BNT162b2 vaccination doses. Our study aims to compare immunogenicity against Omicron prior to and post a booster dose of BNT162b2 in healthy adolescents, and to evaluate their attitudes toward booster dose vaccination. A cross sectional study was conducted among healthy adolescents aged 12-17 who received two doses of BNT162b2 more than 5 months ago. Participants and their guardians performed self-reported questionnaires regarding reasons for receiving the booster. A 30 ug booster dose of BNT162b2 was offered. Immunogenicity was evaluated by a surrogate virus neutralization test (sVNT) against the Omicron variant, and anti-spike-receptor-binding-domain IgG (anti-S-RBD IgG) taken pre-booster and 14-days post-booster. From March to April 2022, 120 healthy Thai adolescents with a median age of 15 years (IQR 14-16) were enrolled. sVNT against Omicron pre- and post-booster had 11.9 (95%CI 0-23.9) and 94.3 (90.6-97.4) % inhibition. Geometric means (GMs) of anti-S-RBD IgG increased from 837 (728, 953) to 3041 (2893, 3229) BAU/mL. Major reasons to receive the booster vaccination were perceived as vaccine efficacy, reduced risk of spreading infection to family, and safe resumption of social activities. A booster dose of BNT162b2 elicits high immunogenicity against the Omicron variant. Motivation for receiving booster doses is to reduce risk of infection.

Therapeutic drug monitoring of meropenem and pharmacokinetic-pharmacodynamic target assessment in critically ill pediatric patients from a prospective observational study.

OBJECTIVES: To compare the unbound plasma meropenem concentrations at mid-dosing intervals (Cmid, 50%fT), end-dosing intervals (Ctrough, 100%fT), and proportions of patients achieving 50%fT and 100%fT above minimum inhibitory concentration (MIC) (50%fT>MIC and 100%fT>MIC) between extended infusion (EI) and intermittent bolus (IB) administration in a therapeutic drug monitoring (TDM) program in children. METHODS: A prospective observational study was conducted in children aged 1 month to 18 years receiving meropenem every 8 hours by either EI or IB. Meropenem Cmid, Ctrough, and proportions of patients achieving 50%fT>MIC and 100%fT>MIC were compared. RESULTS: TDM data from 72 patients with a median age (interquartile range [IQR]) of 12 months (3-37) were used. Meropenem dose was 120 and 60 mg/kg/day in EI and IB groups, respectively. Geometric mean (95% confidence interval [CI]) Cmid of EI versus IB was 17.3 mg/L (13.7-21.8) versus 3.4 mg/L (1.7-6.7) (P <0.001). Geometric mean (95% CI) Ctrough of EI versus IB was 2.3 mg/L (1.6-3.4) versus 0.8 mg/L (0.4-1.5) (P=0.005). Greater proportions of patients achieving 50%fT>MIC and 100%fT>MIC were observed in the EI group. CONCLUSIONS: A meropenem dose of 20 mg/kg/dose given by IB should not be used in critically ill children, even if they are not suspected of having a central nervous system infection. A dose of 40 mg/kg/dose given by EI resulted in higher Cmid, Ctrough, and proportions of patients achieving 50%fT>MIC and 100%fT>MIC.

Keeping It Real: Antibiotic Use Problems and Stewardship Solutions in Low- and Middle-income Countries.

Antimicrobial resistance is a global health threat and there is an urgent need to manage antibiotic use to slow its development. However, antimicrobial stewardship interventions in low- and middle-income countries (LMIC) have been limited in terms of their resourcing, feasibility and effectiveness in the face of greater challenges in child mortality. We sought to gather together examples of antibiotic use problems faced by clinicians in LMIC, many of which are unique to these settings, and real-world antimicrobial stewardship solutions identified, with the goal of learning broader lessons that might be applicable across LMIC.

Keeping It Real: Infection Prevention and Control Problems and Solutions in Low- and Middle-income Countries.

Infection prevention challenges are ubiquitous in healthcare, but some are unique to or more prevalent in low-and middle-income country settings. Despite limited resources, innovative and committed paediatric healthcare providers and infection preventionists have found creative solutions to address the very real and pressing risks their patients face every day. We gathered examples of infection prevention and control challenges faced by clinicians in resource-limited healthcare facilities, and the real-world infection prevention and control solutions they implemented, with the goal of learning broader lessons applicable to low-and middle-income countrie.

Seroprevalence of mumps among children and adolescents in Thailand, 2020.

Thailand has implemented single-dose mumps-containing vaccines since 1997 and two doses since 2010. This study aimed to describe the seroprevalence of mumps among children who received one- or two-dose mumps vaccines. A cross-sectional study of 145 children (aged 3-9 years) and 422 adolescents (10-18 years) was conducted. Mumps IgG seropositivity was defined as ≥ 22 RU/mL by EUROIMMUN ELISA method. The mumps seroprevalence was higher in children (82.1%, 95% CI 74.8-87.9) compared to adolescents (41.7%, 95% CI 37.0-46.6) who had received at least one dose of the mumps vaccine. Among those receiving 2 doses of mumps vaccine at ≥ 5 years after their last mumps vaccination, only 51.3% had maintained IgG ≥ 22 RU/ml. There was a reverse correlation between mumps IgG titer and the time interval from the second dose of mumps vaccine (R = -0.44, p < 0.001). A booster dose of MMR vaccine in young adults may be needed.