We evaluated the effectiveness of personal protective measures, including mask-wearing, handwashing, and social distancing, against COVID-19 infection among contacts of cases. We conducted a case-control study with 211 cases and 839 non-matched controls using all contact tracing records of Thailand’s national Surveillance and Rapid Response Team. Cases were asymptomatic contacts of COVID-19 patients identified between 1 and 31 March 2020 who were diagnosed with COVID-19 by 21 April 2020; controls were asymptomatic contacts who were not diagnosed with COVID-19. Participants were queried about practices during contact periods with a case. Adjusted odds ratios (aOR) and 95% confidence intervals (CI) were estimated for associations between diagnosis of COVID-19 and covariates using multivariable logistic regression models. Wearing masks all the time during contact was independently associated with lower risk of COVID-19 infection compared to not wearing masks (aOR 0.23, 95% CI 0.09– 0.60), while sometimes wearing masks during contact was not (aOR 0.87, 95% CI 0.41–1.84). Maintaining at least 1 meter distance from a COVID patient (aOR 0.15, 95% CI 0.04–0.63), duration of close contact ≤15 minutes versus longer (aOR 0.24, 95% CI 0.07–0.90), and handwashing often (aOR 0.34, 95% CI 0.13–0.87) were significantly associated with lower risk of infection. Type of mask was not independently associated with infection. Those who wore masks all the time also were more likely to practice social distancing. Our findings suggest consistent wearing of masks, handwashing, and social distancing in public to protect against COVID-19 infection.

Objective Despite implementing hepatitis B immunoglobulin (HBIG) and vaccination, data suggest it would not be sufficient to reach the elimination targets. Tenofovir disoproxil fumarate (TDF) has been added to the Thai national standards of care for prevention of transmission of the hepatitis B virus during birth. To optimise national strategies in Thailand, we assessed TDF’s effectiveness for prevention of mother-to-child transmission and conducted cost-effectiveness analyses of different TDF-based strategies. Research design and methods We retrospectively reviewed medical records of mother and infant pairs whose mothers were positive for hepatitis B e-antigen (HBeAg) and received TDF to prevent maternal transmission of viral hepatitis B during 2018–2020. Based on the available data on transmission rate, we also applied a decision tree to estimate the cost-effectiveness of different TDF-based strategies to eligible mothers. These included: (1) HBIG for all hepatitis B virus (HBV) exposed infants; (2) HBIG for only infants of HBeAg-positive mothers (‘HBIG for e-positive’) and (3) without HBIG to infants (‘HBIG-free’). The incremental cost-effectiveness ratio between the different strategies and baseline intervention without TDF was calculated. The one-way sensitivity analysis was used to adjust prevalence of HBeAg-positive mothers, cost of HBIG, cost of TDF and transmission rate. Results Of 223 infants enrolled, 212 (95.0%) received HBIG, while 11 (5.0%) did not. None of the infants had chronic HBV infection. The most cost-saving intervention was ‘HBIG-free’ followed by ‘HBIG for e-positive’. The one-way sensitivity demonstrated that the results were reasonably robust to changes. The cost-saving was greater with a higher hepatitis B virus surface antigen (HBsAg) prevalence. The HBIG-free strategy remained best at 0%–1.4% transmission rates, meeting the additional target for eliminations. Conclusion The study is the first cost-effectiveness analyses to provide evidence supporting an HBIG-free strategy in an antiviral era. This approach should be considered to prevent mother-to-child transmission in resource-constrained settings, particularly in countries with a high HBsAg prevalence.

Background: Despite the implementation of hepatitis B immunoglobulin (HBIG) and vaccination, mother-to-child transmission (MTCT) of hepatitis B virus (HBV) still occurs in 5-10% of HBeAg-positive mothers. Tenofovir Disoproxil Fumarate (TDF) has been added during pregnancy to reduce HBV-DNA at birth, suggesting that HBIG might not be required for newborns. Methods: We retrospectively assessed the effectiveness of TDF in preventing MTCT among HBeAg-positive mothers according to Thai national guidelines during 2018-2020. Based on the available data of transmission rate, we also applied a decision tree to estimate the cost-effectiveness of different TDF-based strategies to eligible mothers. These included [1] HBIG for all HBV-exposed infants ('HBIG for all') [2] HBIG for only infants of HBeAg-positive mothers ('HBIG for HBeAg positive') and [3] without HBIG to infants ('HBIG-free') The incremental cost-effectiveness ratio (ICER) between the different strategies and baseline intervention without TDF was calculated. Findings: Of 223 infants enrolled, 212(95.0%) received HBIG while 11(5.0%) did not. None of the infants had chronic HBV infection. The most cost-saving intervention was 'HBIG-free' with an ICERs of US$ -1603.7(-5644.3 to -673.3), followed by 'HBIG for HBeAg positive' with an ICER of -780.0(-3996.9 to 150.5). The cost-effectiveness was greater with a higher HBeAg prevalence. The 'HBIG-free' strategy could lead to transmission rates of 0-1.4%, which meets the additional target for eliminations. Interpretations: The study is the first cost-effectiveness analysis to provide evidence supporting HBIG-free strategy in the era of antivirals. This approach should be considered for preventing MTCT in resource-constrained settings, particularly in countries with high HBeAg prevalence. Funding Information: This research project is supported by the Ratchadapisek Sompoch Endowment Fund (2021) under Telehealth Cluster, Chulalongkorn University for data collection process including patient recruitment and operational, and data analysis. Publication fee was supported by Thailand Research Fund (TRF) Senior Research Scholar (RTA6280004) and Center of Excellence in Hepatitis and Liver Cancer, Chulalongkorn University. For laboratory cost during data collection process was supported by Field Epidemiology Training Program – Thailand. Declaration of Interests: We declare no competing interests. Ethics Approval Statement: This study protocol was approved by the Ethical Review Committee for Research in Human Subjects, Ministry of Public Health, Thailand.