initiation for MDR/RR-TB is attributed to 10 countries, with India, Indonesia, the Philippines, Nigeria and Pakistan making up with more than half of this gap [1]. In 2020, the treatment success rate for first-line regimens was 86% overall the rate is lower (77%) for PLHIV and higher (88%) in children (aged 15 years). WHO treatment success rates are calculated as the proportion of individuals whose outcome is either classed as cured (conversion to smear- or culture-negative) or treatment completed (completed treatment without of smear or culture results), among all bacteriologically confirmed and clinically diagnosed TB cases in the same period [30]. These rates have been almost constant over the last 20 years. The success rate for MDR/RR-TB treatment is lower overall but has improved in recent years, with success rates for second-line regimens in 2019 estimated at 60%, compared with 50% in 2012 [28]. Despite the COVID-19 pandemic, treatment success estimates in 2020 remained at the same level as 2019 (68%). Treatment outcomes measured for PLHIV diagnosed with TB in 2020 were: 77% success, 1.4% failure and 11% death. The remaining cases were either lost to follow-up or not evaluated [1]. In the global population (including both PLHIV and the HIV-negative population), treatment failure and death represented 0.7% and 4.2% of treatment outcomes, respectively. In children, the global treatment success rate in 2020 was 88% [31]. In MDR/RR-TB globally, treatment failure has remained more or less constant at 10% from 2012 to 2019 [31]. Costs One of the End TB Strategy targets is the complete elimination of catastrophic costs related to TB for affected households [4]. The term “catastrophic cost” is used when over 20% of a household pre-TB annual income is used for TB-related expenditures (including income loss) [1]. This target was set to prevent financial and economic burden from impeding TB diagnosis and treatment. Currently, even though TB treatment is free of charge, over half of TB patients and their households face catastrophic costs as a result of the disease. The WHO has survey data for 27 countries on the percentage of TB households facing catastrophic costs, which show a broad range, from 13% in El Salvador to 92% in the Solomon Islands. For people with DR-TB the average was much higher, at 82% [1]. The impact of COVID-19 The COVID-19 pandemic set back the fight against TB by at least several years. At present, this impact is most acutely felt in a sharp decline in the number of people with newly diagnosed TB. Assuming this decrease indicates a reduction in diagnosis (and not a true decline in TB incidence), the number of undiagnosed and untreated TB cases in the community will accumulate, as transmission from undiagnosed cases in communities continues, and with some lag-time, the number of people dying from TB will rise. Model projections estimate an increase in TB mortality of up to 20% in high-burden settings over the next 5 years [1, 32]. The question remains whether a partial decline in TB notifications might represent a true reduction in TB incidence. The vast majority of this decrease is believed to be due to underreporting as TB care (equipment and health professionals) and funding were diverted to the COVID-19 response [33] however, this does not preclude the possibility of a simultaneous decline in M. tuberculosis transmission due to COVID-19 mitigation measures. In 2020, the number of TB case notifications fell by 18% (figure 2b), with a partial recovery in 2021 [34]. Among the 30 countries with a high TB burden and the three global TB watchlist countries (Cambodia, the Russian Federation and Zimbabwe, countries that exited the high-burden category but remain a priority for WHO support [1]), the highest relative reduction was seen in the Philippines, Lesotho, Indonesia, Zimbabwe, India, Myanmar and Bangladesh, https://doi.org/10.1183/2312508X.10023922 23 EPIDEMIOLOGY |R. VERSTRAETEN ET AL.