Carbon emissions associated with antenatal testing for hepatitis B prophylaxis eligibility, the Gambia.

OBJECTIVE

To estimate the carbon footprint of three diagnostic strategies to identify pregnant women eligible for antiviral prophylaxis to prevent hepatitis B vertical transmission in the Gambia.

METHODS

In 2024, we conducted a life cycle assessment of a point-of-care polymerase chain reaction (PCR) test using plasma, and a rapid diagnostic test for hepatitis B core-related antigen (HBcrAg) using plasma and capillary blood across three hospitals (rural, suburban and urban) and a suburban health centre. We included all products and processes in each diagnostic strategy. The functional unit was an antenatal testing episode assessing eligibility for antiviral prophylaxis, beginning after positive hepatitis B surface antigen screening. We estimated carbon emissions in grams of carbon dioxide equivalent (g CO2e) ± uncertainty.

FINDINGS: Mean carbon emissions per strategy were significantly different between point-of-care PCR and the rapid diagnostic tests (P-value: 0.028): 1619.0 ± 200.6 g CO2e (PCR), 520.4 ± 59.1 g CO2e (plasma-based rapid diagnostic test) and 374.3 ± 50.4 g CO2e (capillary-based test). Higher emissions with the PCR test were mainly driven by its reliance on air conditioning (759.1 g CO2e compared with 125.2 g CO2e for plasma-based rapid diagnostic test and 24.3 g CO2e for capillary-based test); the test itself (290.0 g CO2e versus 129.0 g CO2e for rapid diagnostic tests); and PCR-specific requirements including diagnostic device (47.0 g CO2e) and additional patient travel to collect results (255.8 g CO2e).

CONCLUSION

Our findings suggest that HBcrAg rapid diagnostic tests can reduce emissions substantially compared with point-of-care PCR. Our study demonstrates that life cycle assessments are feasible in resource-constrained settings and highlights the importance of integrating sustainability into hepatitis B diagnostic strategies.