Implications of the COVID-19 pandemic on eliminating trachoma as a public health problem

Abstract

Background: Progress towards elimination of trachoma as a public health problem has been substantial, but the COVID-19 pandemic has disrupted community-based control efforts. Methods: We use a susceptible-infected model to estimate the impact of delayed distribution of azithromycin treatment on the prevalence of active trachoma. Results: We identify three distinct scenarios for geographic districts depending on whether the basic reproduction number and the treatment-associated reproduction number are above or below a value of one. We find that when the basic reproduction number is below one, no significant delays in disease control will be caused. However, when the basic reproduction number is above one, significant delays can occur. In most districts a year of COVID-related delay can be mitigated by a single extra round of mass drug administration. However, supercritical districts require a new paradigm of infection control because the current strategies will not eliminate disease. Conclusion: If the pandemic can motivate judicious, community-specific implementation of control strategies, global elimination of trachoma as a public health problem could be accelerated.

Modelling trachoma post-2020: opportunities for mitigating the impact of COVID-19 and accelerating progress towards elimination

“…The first two settings (Setting 1 and Setting 2) were intended to represent districts that would have been expected to reach the TF 1–9 <5% threshold before 2030 with a strategy of annual district-level MDA targeting the whole community, but where an interruption is expected to cause a delay in achieving this control threshold. This corresponds to ‘MDA subcritical’ as defined by Blumberg et al, 12 with R 0 >1 and R T <1.…”

“… 10 , 11 In the context of programmatic activities being temporarily halted due to COVID-19, this is especially concerning for districts with previously high prevalence of trachoma that are midway through elimination programmes. Furthermore, for a limited number of districts, the reproductive number under annual treatment ( R T ) has been estimated as being >1 (defined as ‘MDA super-critical’ by Blumberg et al), 12 suggesting that for this minority of districts, elimination is not achievable under a strategy of annual MDA. 12 , 13 For such districts there is concern that the interruption to programmes may cause a particularly marked surge in transmission with unknown consequences for morbidity.…”

“…Furthermore, for a limited number of districts, the reproductive number under annual treatment ( R T ) has been estimated as being >1 (defined as ‘MDA super-critical’ by Blumberg et al), 12 suggesting that for this minority of districts, elimination is not achievable under a strategy of annual MDA. 12 , 13 For such districts there is concern that the interruption to programmes may cause a particularly marked surge in transmission with unknown consequences for morbidity. Regardless of the impact of COVID-19, these districts may need to implement alternative control strategies if EPHP is to be achieved.…”

“…Regardless of the impact of COVID-19, these districts may need to implement alternative control strategies if EPHP is to be achieved. 12 …”

Neglected tropical disease control in a world with COVID-19: an opportunity and a necessity for innovation

“… 4 In such settings, the current modelling suggests biannual or quarterly MDA could help catch up on missed MDA rounds and help accelerate progress towards the 2030 trachoma goals. 5 The benefits of more frequent MDA have been demonstrated with a randomized trial that found quarterly MDA targeted at children was more effective in reducing Chlamydia trachomatis infection compared with community-wide annual MDA. 6 While benefits of more frequent MDA need to be balanced against cost and logistical considerations, shorter programmes are likely to yield cost savings in the long-term, as well as reduce the total amount of antibiotics required and the likelihood of antimicrobial resistance emerging.…”