Abstract

STRAND 6: Collaboration across boundaries: Data community and statistics research community coming together
Title: Impact of the first COVID-19 lockdown on HIV diagnosis in England
Feysal Kemal Muhammed1, Peter Kirwan2, Tasnuva Tabassum2, James Lester3, Pantelis Samartsidis2, Alison Brown3, Daniela De Angelis2, Chiara Chiavenna4, and Anne Presanis2
1Department of Statistics, Hawassa University, Ethiopia
2MRC Biostatistics Unit, University of Cambridge, UK
3UK Health Security Agency, UK
4Bocconi Institute for Data Science and Analytics, Bocconi University, Italy
STI and HIV prevention and care services in England were unavoidably disrupted by the COVID-19 lockdowns, and it is likely incidence was also affected. We estimated the magnitude of the effect of the first UK COVID-19 lockdown in March 2020 on subsequent HIV diagnoses, using the quarterly time series of observed diagnoses during the period 2004 to 2020. We used a Bayesian Structural Time Series model to estimate the counterfactual number of new HIV diagnoses in the post-lockdown period that would have occurred in the absence of lockdown. This counterfactual was constructed using synthetic controls (time series correlated with HIV diagnoses unaffected by pre-lockdown) based on Google Trend data. The effect was estimated as the difference between the counterfactual and the observed number of diagnoses, for strata defined by gender, sexual orientation, age, and whether or not the diagnosis was late. All strata had greater than 50% posterior probability that the first COVID-19 lockdown had an effect on HIV diagnosis, with the highest posterior probability of an effect (99%) in heterosexual men aged 50+ with late diagnosis. The estimated overall number of missed diagnoses was 97 (95% prediction interval [-688, 850]). We found that the effect size varied by stratum and by time since the lockdown, with the largest effect in the first quarter after the lockdown. The effect then reduced, as HIV testing, and consequent diagnosis, caught up during the summer of 2020. As the number of new HIV diagnoses made in England and estimated incidence fell consistently in the five years pre-pandemic, we hypothesise that the effect of the lockdown may have been less pronounced than it could have been if the epidemic had not already been in decline. Public health campaigns which encouraged HIV home testing during the lockdown may also have helped to mitigate the effect.