Prevalence and clinical manifestations of cutaneous findings in patients with adult-onset immunodeficiency due to anti-interferon gamma autoantibodies: an eight-year retrospective study.

BACKGROUND: Cutaneous findings in adult-onset immunodeficiency due to anti-interferon gamma autoantibodies (anti-IFN-γ autoAbs) are common. Currently, data on this topic are scarce. METHODS: We retrospectively reviewed medical records of 202 skin episodes from 77 patients diagnosed with adult-onset immunodeficiency due to anti-IFN-γ autoAbs. The exclusion of drug eruptions left 180 episodes from 74 patients for further analysis. RESULTS: Reactive dermatosis was diagnosed in 66.1%, followed by disseminated skin infection (18.3%) and local skin infection (15.6%). Neutrophilic dermatosis (ND) tended to appear on the upper part of bodies, while leg lesions were common in the non-ND. Disseminated infection occurred more frequently with ND. Mycobacterium abscessus was the most common pathogen of concomitant infection. Remission was achieved in 21.6% and was significantly associated with females. CONCLUSION: Reactive dermatosis was the most common skin manifestation. ND was found in the upper part of bodies and associated with disseminated infection. Drug-free remission was scarcely achieved.

Long-term multiple metabolic abnormalities among healthy and high-risk people following nonsevere COVID-19.

Few studies have identified the metabolic consequences of the post-acute phase of nonsevere COVID-19. This prospective study examined metabolic outcomes and associated factors in nonsevere, RT-PCR-confirmed COVID-19. The participants' metabolic parameters, the prevalence of long-term multiple metabolic abnormalities (≥ 2 components), and factors influencing the prevalence were assessed at 1, 3, and 6 months post-onset. Six hundred individuals (mean age 45.5 ± 14.5 years, 61.7% female, 38% high-risk individuals) with nonsevere COVID-19 attended at least one follow-up visit. The prevalence of worsening metabolic abnormalities was 26.0% for BMI, 43.2% for glucose, 40.5% for LDL-c, 19.1% for liver, and 14.8% for C-reactive protein. Except for lipids, metabolic-component abnormalities were more prevalent in high-risk hosts than in healthy individuals. The prevalence of multiple metabolic abnormalities at the 6-month follow-up was 41.3% and significantly higher in high-risk than healthy hosts (49.2% vs 36.5%; P = 0.007). Factors independently associated with a lower risk of these abnormalities were being female, having dyslipidemia, and receiving at least 3 doses of the COVID-19 vaccine. These findings suggest that multiple metabolic abnormalities are the long-term consequences of COVID-19. For both high-risk and healthy individuals with nonsevere COVID-19, healthcare providers should monitor metabolic profiles, encourage healthy behaviors, and ensure complete vaccination.

Immunogenicity and reactogenicity of fractional, heterologous primary COVID-19 vaccination schedules with BNT162b2 boosters in 5-11-year-old Thai children: A multicenter, prospective, double-blind, randomized control trial.

OBJECTIVE: To evaluate immunogenicity and safety of heterologous COVID-19 primary vaccination regimens of CoronaVac with fractional and standard BNT162b2 dosages in 5-11-year-old Thai children. METHODS: This prospective, multicenter, double-blind, randomized control trial divided participants 1:1:1:1 to receive a second dose of either standard (10-µg) or half-dose (5-µg) BNT162b2 vaccines as follows: CoronaVac/10-µg-BNT162b2 (Group 1), CoronaVac/5-µg-BNT162b2 (Group 2), 10-µg-BNT162b2/10-µg-BNT162b2 (Group 3), or 10-µg-BNT162b2/5-µg-BNT162b2 (Group 4). A subset of participants from each arm received 10-µg-BNT162b2 booster (third) doses 16 weeks after their second vaccination. Humoral and cellular immunogenicity were assessed and adverse events (AEs) digitally self-reported. RESULTS: Of 553 enrolled participants, 50 % were male, the median (interquartile range) age was 8.65 (7.00, 10.00) years, and a majority (91 %) had normal weight-for-height. All participants exhibited similarly robust neutralizing antibodies (NAb) against the ancestral Wuhan strain two weeks after the second vaccination, with titers highest in Group 1 (737.60, 95% CI [654.80, 830.88]), followed by Groups 3 (630.42, 95% CI [555.50, 715.45]), 2 (593.98, 95% CI [506.02, 697.23]), and 4 (451.79, 95% CI [388.62, 525.23]), as well as 56.01 % and 49.68 % seroconversion for BA.1 and BA.5, respectively. Half-dose BNT162b2 as a second dose induced significantly lower NAb titers compared to their respective full-dose regimens (p = 0.03 for Groups 1 vs 2 and p < 0.001 for Groups 3 vs 4). 77.71 % of participants developed SARS-CoV-2 ancestral spike protein-specific T-cell responses two weeks after the second vaccination. This was similar across arms. Booster doses generated NAb titers 5.69-11.51-folds higher than the second vaccination against BA.1. AEs were similar across arms, all mild or moderate, and fully resolved 2-3 days thereafter. CONCLUSION: Standard and fractional heterologous regimens of CoronaVac-BNT162b2 induced similar or higher humoral immunity than homologous BNT162b2 and represent alternative vaccine regimens for children. These findings are highly relevant in settings concurrently using both vaccines.

The immunogenicity and reactogenicity of four COVID-19 booster vaccinations against SARS-CoV-2 variants following CoronaVac or ChAdOx1 nCoV-19 primary series.

BACKGROUND: The appropriate COVID-19 booster vaccine following inactivated or adenoviral vector COVID-19 vaccination is unclear. OBJECTIVE: To investigate the immunogenicity of four COVID-19 booster vaccines. METHODS: We prospectively enrolled healthy adults who received a two-dose CoronaVac or ChAdOx1 8-12 weeks earlier and allocated them to receive one of the following booster vaccine: inactivated (BBIBP-CorV), ChAdOx1 or mRNA (BNT162b2 at full [30 µg] and half [15 µg] dose) vaccines. We determined the reactogenicity and the humoral (anti-receptor binding domain IgG (anti-RBD-IgG), neutralizing antibodies (nAb) against Delta, Beta and Omicron variants) and cellular immunity measuring by interferon gamma (IFN-γ) responses post-booster. AR patients. RESULTS: Among the 352 participants (179 CoronaVac and 173 ChAdOx1 participants), 285 (81%) were female, and median age was 39 (IQR: 31-47) years. Two weeks post-booster, both 30 µg- and 15 µg- BNT162b2 induced the highest anti-RBD IgG concentration (BAU/mL); Coronavac-prime: 30 µg-BNT162b2, 5152.2 (95%CI 4491.7-5909.8); 15 µg-BNT162b2, 3981.1 (3397.2-4665.4); ChAdOx1, 1358.0 (1141.8-1615.1); BBIBP-CorV, 154.6 (92.11-259.47); ChAdOx1-prime: 30 µg-BNT162b2, 2363.8 (2005.6-2786.1; 15 µg-BNT162b2, 1961.9 (1624.6-2369.1); ChAdOx1, 246.4 (199.6-304.2); BBIBP-CorV, 128.1 (93.5-175.4). Similarly, both 30 µg- and 15 µg- BNT162b2 boosting induced the highest nAb titers against Beta, Delta and Omicron BA.1 variants and highest T-cell response at 2 weeks after boosting. While all BNT162b2 or heterologous ChAdOx1-boosted participants had nAb against Omicron, these were < 50% for BBIBP-CorV and 75% for homologous ChAdOx1-boosted participants. There was significant decrease in nAb ( > 4-fold) at 16-20 weeks post booster for all groups. CONCLUSIONS: Heterologous boosting with BNT162b2 following CoronaVac or ChAdOx1 primary series is most immunogenic. Additional studies are needed to verify the clinical efficacy and persistence of immunity following half-dose BNT162b2.

Immunogenicity and reactogenicity of heterologous COVID-19 vaccination in pregnant women.

This open-labeled non-inferiority trial evaluated immunogenicity and reactogenicity of heterologous and homologous COVID-19 vaccination schedules in pregnant Thai women. 18-45-year-old pregnant women with no history of COVID-19 infection or vaccination and a gestational age of ≥12 weeks were randomized 1:1:1 into three two-dose primary series scheduled 4 weeks apart: BNT162b2-BNT162b2 (Group 1), ChAdOx1-BNT162b2 (Group 2), and CoronaVac-BNT162b2 (Group 3). Serum antibody responses, maternal and cord blood antibody levels at delivery, and adverse events (AEs) following vaccination until delivery were assessed. The 124 enrolled participants had a median age of 31 (interquartile range [IQR] 26.0-35.5) years and gestational age of 23.5 (IQR 18.0-30.0) weeks. No significant difference in anti-receptor binding domain (RBD) IgG were observed across arms at 2 weeks after the second dose. Neutralizing antibody geometric mean titers against the ancestral Wuhan strain were highest in Group 3 (258.22, 95% CI [187.53, 355.56]), followed by Groups 1 (187.47, 95% CI [135.15, 260.03]) and 2 (166.63, 95% CI [124.60, 222.84]). Cord blood anti-RBD IgG was correlated with, and equal to or higher than, maternal levels at delivery (r = 0.719, P < .001) and inversely correlated with elapsed time after the second vaccination (r = -0.366, P < .001). No significant difference in cord blood antibody levels between groups were observed. Local and systemic AEs were mild-to-moderate and more frequent in Group 2. Heterologous schedules of CoronaVac-BNT162b2 or ChAdOx1-BNT162b2 induced immunogenicity on-par with BNT162b2-BNT162b2 and may be considered as alternative schedules for primary series in pregnant women in mRNA-limited vaccine settings.

Dynamics of Antibody Responses after Asymptomatic and Mild to Moderate SARS-CoV-2 Infections: Real-World Data in a Resource-Limited Country.

The dynamics of humoral immune responses of patients after SARS-CoV-2 infection is unclear. This study prospectively observed changes in anti-receptor binding domain immunoglobulin G (anti-RBD IgG) and neutralizing antibodies against the Wuhan and Delta strains at 1, 3, and 6 months postinfection between October 2021 and May 2022. Demographic data, clinical characteristics, baseline parameters, and blood samples of participants were collected. Of 5059 SARS-CoV-2 infected adult patients, only 600 underwent assessment at least once between 3 and 6 months after symptom onset. Patients were categorized as immunocompetent (n = 566), immunocompromised (n = 14), or reinfected (n = 20). A booster dose of a COVID-19 vaccine was strongly associated with maintained or increased COVID-19 antibody levels. The booster dose was also more strongly associated with antibody responses than the primary vaccination series. Among patients receiving a booster dose of a mRNA vaccine or a heterologous regimen, antibody levels remained steady or even increased for 3 to 6 months after symptom onset compared with inactivated or viral vector vaccines. There was a strong correlation between anti-RBD IgG and neutralizing antibodies against the Delta variant. This study is relevant to resource-limited countries for administering COVID-19 vaccines 3 to 6 months after infection.

Early antiviral and supervisory dexamethasone treatment improve clinical outcomes of nonsevere COVID-19 patients.

This study aimed to evaluate the efficacy of early antiviral treatment in preventing clinical deterioration in asymptomatic or mildly symptomatic severe acute respiratory syndrome coronavirus 2 infected (COVID-19) patients in home isolation and to share our experiences with the ambulatory management of nonsevere COVID-19 patients. This retrospective study included mild COVID-19 adult patients confirmed by real-time reverse transcription-polymerase chain reaction. They received care via an ambulatory management strategy between July 2021 and November 2021. Demographic data, clinical progression, and outcomes were collected. Both descriptive and inferential statistics were performed to illustrate the cohort's characteristic and outcomes of the study. Univariable and multivariable logistic regression models were employed to investigate the associations between clinical factors and disease progression. A total of 1940 patients in the Siriraj home isolation system met the inclusion criteria. Their mean age was 42.1 ±â€…14.9 years, with 14.2% older than 60 years, 54.3% female, and 7.1% with a body weight ≥ 90 kg. Only 115 patients (5.9%) had deterioration of clinical symptoms. Two-thirds of these could be managed at home by dexamethasone treatment under physician supervision; however, 38 of the 115 patients (2.0% of the study cohort) needed hospitalization. Early favipiravir outpatient treatment (≤ 5 days from onset of symptoms) in nonsevere COVID-19 patients was significantly associated with a lower rate of symptom deterioration than late favipiravir treatment (50 [4.6%] vs 65 [7.5%] patients, respectively; P = .008; odds ratio 1.669; 95% confidence interval, 1.141-2.441). The unfavorable prognostic factors for symptom deterioration were advanced age, body weight ≥ 90 kg, unvaccinated status, higher reverse transcription-polymerase chain reaction cycle threshold, and late favipiravir treatment. The early delivery of essential treatment, including antiviral and supervisory dexamethasone, to ambulatory nonsevere COVID-19 patients yielded favorable outcomes during the COVID-19 pandemic in Thailand.

Evaluation of the Safety and Immunogenicity of Fractional Intradermal COVID-19 Vaccines as a Booster: A Pilot Study.

Intradermal vaccination using fractional dosages of the standard vaccine dose is one strategy to improve access to COVID-19 immunization. We conducted a pilot study in healthy adults in Thailand to evaluate the safety and immunogenicity of intradermal administration of fractional doses of ChAdOx1 (1/5th of standard dosage) or BNT162b2 (1/6th of standard dosage) to individuals previously vaccinated (prime) with two-dose intramuscular CoronaVac, ChAdOx1 or BNT162b2. Following an initial immunogenicity exploratory phase for each vaccine combination group (n = 10), a total of 135 participants (n = 45 per group) were recruited to 3 groups (CoronaVac prime-intradermal BNT162b2 boost, CoronaVac prime-intradermal ChAdOx1 boost and ChAdOx1 prime-intradermal BNT162b2 boost) and their immunogenicity data were compared to a previous cohort who received the same vaccine intramuscularly. Two weeks following booster vaccination, neutralizing antibodies against the delta variant were similar between the participants who received intradermal and intramuscular vaccination. However, neutralizing antibodies against the omicron variant in the intradermal BNT162b2 boost groups were ~6-fold lower, while the levels in the ChAdOx1 boost group were similar compared to their respective vaccine regimen given intramuscularly. The intradermal booster significantly increased spike-specific T cell responses in all three groups from pre-booster levels. Local and systemic adverse reactions were milder in intradermal compared to intramuscular injections. Further studies are needed to evaluate the clinical relevance of these findings and the feasibility of administration of intradermal COVID-19 vaccines.

Early diagnosis by antigen test kit and early treatment by antiviral therapy: An ambulatory management strategy during COVID-19 crisis in Thailand.

This study aimed to assess the clinical characteristics of patients who registered at the Siriraj Favipiravir Clinic and to share our experiences in this comparatively unique clinical setting. This retrospective study included patients who registered at the Siriraj Favipiravir Clinic during August 11, 2021 to September 14, 2021. Included adult patients were those with severe acute respiratory syndrome coronavirus 2 (coronavirus disease 2019 [COVID-19]) infection confirmed by antigen test kit (ATK) or real-time reverse transcription-polymerase chain reaction, no favipiravir contraindication, no prior COVID-19 treatment, and not receiving care from another medical facility. Demographic data and outcomes were collected and analyzed. Of the 1168 patients (mean age: 44.8 ± 16.4 years, 55.7% female) who registered at the clinic, 117 (10%) did not meet the treatment criteria, and 141 (12%) patients did not pick up their medication. One-third of patients had at least 1 symptom that indicated severe disease. Higher proportion of unvaccinated status (56.7% vs 47.5%, P = .005), higher proportion of persons with risk factors for disease progression (37.7% vs 31.3%, P = .028), and longer duration between the date of clinic registration and the date of positive diagnostic test (3 vs 2 days, P = .004) were significantly more commonly observed in the severe disease group compared to the nonsevere disease group. The duration between symptom onset and the date of clinic registration was significantly longer in the real-time reverse transcription-polymerase chain reaction group than in the ATK group (6 vs 4 days, P < .001). Most patients (90.0%) had completed favipiravir treatment regimen. The improvement and mortality rates were 86.7% and 1.2%, respectively. COVID-19 severity is associated with vaccination status, baseline risk factors, and timing between disease detection and treatment. The use of ATK influences patients to seek treatment significantly earlier in ambulatory setting. Our early diagnosis and antiviral treatment strategy yielded favorable results in an outpatient setting during a COVID-19 outbreak in Thailand.

SARS-CoV-2 Antibody Response against Mild-to-Moderate Breakthrough COVID-19 in Home Isolation Setting in Thailand.

Background: In December 2021, Omicron replaced Delta as the dominant coronavirus disease 2019 (COVID-19) variant in Thailand. Both variants embody diverse epidemiological trends and immunogenicity. We investigated whether Delta and Omicron patients' biological and clinical characteristics and immunogenicity differed post-COVID-19 infection. Methods: This retrospective cohort study investigated the clinical outcomes and laboratory data of 5181 patients with mild-to-moderate COVID-19 (Delta, 2704; Omicron, 2477) under home isolation. We evaluated anti-receptor-binding domain immunoglobulin G (anti-RBD IgG) and surrogate viral neutralizing (sVNT) activity in 495 individuals post-COVID-19 infection during the Delta pandemic. Results: Approximately 84% of all patients received favipiravir. The median cycle threshold (Ct) values were lower for Omicron patients than Delta patients (19 vs. 21; p < 0.001), regardless of vaccination status. Upper respiratory tract symptoms were more frequent with Omicron patients than Delta patients. There were no significant associations between Ct and Omicron symptoms (95% confidence interval 0.98−1.02). A two-dose vaccine regimen reduced hospital readmission by 10% to 30% and death by under 1%. Anti-RBD IgG and sVNT against Delta were higher among older individuals post-COVID-19 infection. Older individuals expressed anti-RBD IgG and sVNT for a more extended period after two-dose vaccination than other age groups. Conclusions: After a full vaccination course, breakthrough mild-to-moderate Delta and Omicron infections have limited immunogenicity. Prior infections exert reduced protection against later reinfection or infection from novel variants. However, this protection may be sufficient to prevent hospitalization and death, particularly in countries where vaccine supplies are limited.

Measles seroprevalence in Thailand: are adolescents and young adults at risk of measles?

INTRODUCTION: During the last decade, measles has become an important re-emerging disease in Thailand. The objective of this study was to measure measles seroprevalence and its influencing factors and to plan for an improved vaccination program. METHODS: A total of 600 participants aged between 9 months and 50 years were divided into seven groups those represent birth cohorts that experienced different measles vaccination policies. Participants' blood samples were obtained to measure measles immunoglobulin G (IgG) levels. RESULTS: None of the participants in the 9-month age group had measles IgG levels beyond a protective level. Participants in the following age groups: 2 ½, 5-15, 16-29, 30-33, 34-40, and 41-50 years had 82% (95% confidence interval [CI] 73.3-90.7), 50% (95% CI 36.1-63.9), 52% (95% CI 42.3-62.7), 70% (95% CI 61.1-78.9), 88.8% (95% CI 84.1-93.5), and 98.8% (95% CI 96.4-100.0) measles seropositivity, respectively. The study did not find any significant factors affecting measles seropositivity. CONCLUSION: Individuals aged 15-34 years are vulnerable to measles infections. Supplementary vaccination in special situations, including post-exposure prophylaxis during an outbreak among young adults or providing for high-risk occupations, such as healthcare personnel, should be encouraged.

Comparison of safety and immunogenicity of CoronaVac and ChAdOx1 against the SARS-CoV-2 circulating variants of concern (Alpha, Delta, Beta) in Thai healthcare workers.

Background: Inactivated vaccine (CoronaVac) and chimpanzee adenovirus-vector vaccine (ChAdOx1) have been widely used in resource-limited settings. However, the information on the reactogenicity and immunogenicity of these two vaccines in the same setting are limited. Methods: Healthy health care workers (HCWs) aged 18 years or older were randomly assigned to receive either two doses of CoronaVac at 4 weeks interval or two doses of ChAdOx1 at 10 weeks interval. Self-reported adverse events (AEs) were collected for 7 days following each vaccination. Immunogenicity was determined by IgG antibodies levels against receptor binding domain (RBD) of the SARS-CoV-2 spike protein (S1 subunit) and the 50% plaque reduction neutralization titers against various strains. Results: Of the 360 HCWs, 180 in each vaccine group, the median (interquartile range: IQR) age was 35 (29-44) years old and 84.2% were female. Participants who received ChAdOx1 reported higher frequency of AEs than those received CoronaVac after both the first dose (84.4% vs. 66.1%, P < 0.001) and second dose (75.6% vs. 60.6%, P = 0.002), with more AEs in those younger than 30 years of age for both vaccines. The seroconversion rates were 75.6% and 100% following the first dose of CoronaVac and ChAdOx1, respectively. All participants were seropositive at 2 weeks after the second dose. The anti-SARS-CoV-2 RBD IgG levels induced by CoronaVac was lower than ChAdOX1 with geometric means of 164.4 and 278.5 BAU/mL, respectively (P = 0.0066). Both vaccines induced similar levels of neutralizing antibodies against the Wuhan strain, with the titers of 337.4 and 331.2; however, CoronaVac induced significantly lower GMT against Alpha (23.1 vs. 92.5), Delta (21.2 vs. 69.7), and Beta (10.2 vs. 43.6) variants, respectively. Conclusion: CoronaVac induces lower measurable antibodies against circulating variants but with lower frequency of AEs than ChAdOx1. An earlier boosting to prevent breakthrough infections may be needed.

Development of a New Scoring System To Accurately Estimate Learning Outcome Achievements via Single, Best-Answer, Multiple-Choice Questions for Preclinical Students in a Medical Microbiology Course.

During the preclinical years, single-best-answer multiple-choice questions (SBA-MCQs) are often used to test the higher-order cognitive processes of medical students (such as application and analysis) while simultaneously assessing lower-order processes (like knowledge and comprehension). Consequently, it can be difficult to pinpoint which learning outcome has been achieved or needs improvement. We developed a new scoring system for SBA-MCQs using a step-by-step methodology to evaluate each learning outcome independently. Enrolled in this study were third-year medical students (n = 316) who had registered in the basic microbiology course at the Faculty of Medicine, Siriraj Hospital, Mahidol University during the academic year 2017. A step-by-step SBA-MCQ with a new scoring system was created and used as a tool to evaluate the validity of the traditional SBA-MCQs that assess two separate outcomes simultaneously. The scores for the two methods, in percentages, were compared using two different questions (SBA-MCQ1 and SBA-MCQ2). SBA-MCQ1 tested the students' knowledge of the causative agent of a specific infectious disease and the basic characteristics of the microorganism, while SBA-MCQ2 tested their knowledge of the causative agent of a specific infectious disease and the pathogenic mechanism of the microorganism. The mean score obtained with the traditional SBA-MCQs was significantly lower than that obtained with the step-by-step SBA-MCQs (85.9% for the traditional approach versus 90.9% for step-by-step SBA-MCQ1; p < 0.001; and 81.5% for the traditional system versus 87.4% for step-by-step SBA-MCQ2; p < 0.001). Moreover, 65.8% and 87.8% of the students scored lower with the traditional SBA-MCQ1 and the traditional SBA-MCQ2, respectively, than with the corresponding sets of step-by-step SBA-MCQ questions. These results suggest that traditional SBA-MCQ scores need to be interpreted with caution because they have the potential to underestimate the learning achievement of students. Therefore, the step-by-step SBA-MCQ is preferable to the traditional SBA-MCQs and is recommended for use in examinations during the preclinical years.

Seroprevalence of Bordetella pertussis antibodies and anti-pertussis antibody response after a single dose of reduced-antigen combined diphtheria, tetanus, and acellular pertussis vaccine (Tdap) in pregnant Thai women.

BACKGROUND: Maternal immunization with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) has recently been implemented to prevent infant pertussis. Tdap is still not routinely recommended in Thailand, and there are limited data to support or challenge this strategy. OBJECTIVES: The primary aim was to determine the seroprevalence of anti-pertussis toxin antibodies (anti-PT IgG) among pregnant Thai women. The secondary aims were to evaluate antibodies response after Tdap vaccination between seronegative and seropositive mothers and to compare the different antibody titers at delivery among seropositive mothers who received Tdap to those who received tetanus-diphtheria vaccine (Td). METHODS: This randomized clinical trial was conducted during April 2018 to April 2019 at Siriraj Hospital, Bangkok, Thailand. A total of 129 pregnant women were included. Paired blood samples for anti-PT IgG levels were obtained during the first antenatal visit and at delivery. A baseline cut-off value of <5 IU/ml indicated seronegativity. There were 29 exclusions from the original 129 enrollment. All seronegative participants (n = 69) received Tdap, while the seropositive group were randomized 1:1 to receive either Tdap (n = 18) or Td (n = 13) during 27-36 weeks' gestation. The antibody levels from both sera were compared between groups. RESULTS: The seroprevalence of maternal anti-PT IgG was 33.3% (43/129). There was no significant difference in the increment of antibody levels after Tdap vaccination between the seronegative and seropositive groups (30.2 vs. 42 IU/ml; p = 0.183). Among seropositive groups, all Tdap recipients had increased antibody titers at delivery, while all Td recipients showed waning of immunity throughout gestation. (42 IU/ml vs. -7.4 IU/ml; p < 0.001). CONCLUSION: Most pregnant Thai women have seronegative against pertussis. Most seropositive mothers had initial low antibody titers and their immunity significantly decreased before delivery. Our findings highlight the need for universal pertussis immunization in pregnancy regardless of individual baseline immunity.

Chronic diarrhea and abnormal serum immunoglobulin levels: a case report.

A 15-year-old Thai boy with multiple episodes of chronic diarrhea caused by giardiasis with hypogammaglobulin M and IgG4 subclass deficiency (but normal antibody response to rabies vaccine) is reported. Immune status follow-up is necessary for a definite diagnosis and proper management.