Tuberculosis (TB) remains a significant public health issue for the world. WHO estimated that 9.9 million individuals suffer from TB in 2020. Mycobacterium tuberculosis (MTB) bacterium, a highly aerobic organism, causes TB . Tuberculosis could be divided into active disease or latent disease, based on the presence or absence of clinical symptoms. Typical symptoms of active disease are productive cough with blood-containing sputum, night sweat, low grade fever, and weight loss [2, 3]. Tuberculosis could be transmitted by several routes with the air transmission is the most predominant one. The process by which bacilli are aerosolized is highly correlated with the coughing . The incidence of TB varies from countries to countries. For instance, the highest rates (300 per 100,000 persons or higher) are observed in sub-Saharan Africa, but low rates (less than 25 cases per 100,000 persons) are seen in United States and in Japan . Taiwan is affected by an intermediate TB burden with its incidence rate at 72.5 and 45.7 per 100,000 population in 2005 and 2015, respectively [7, 8].
Due to special components in the cell wall of TB bacilli, there are increasing chances of the anti-TB drug resistance . Clinically, it is appropriate to combine different types of antibiotics to treat active TB in order to lower the chance of antibiotics resistances . Nonetheless, drug-resistant TB remains a main issue in the world, which may be attributed to poor drug compliance or using low-quality medication . Multidrug-resistant tuberculosis (MDR-TB) is defined with resistance to the two most effective first-line TB drugs: rifampicin and isoniazid. Extensively drug-resistant TB (XDR-TB) was simultaneously resistant to three or more of the six classes of second-line drugs but has been defined as TB caused by Mycobacterium tuberculosis strains resistant to isoniazid, rifampicin, any fluoroquinolone, and either bedaquiline or linezolid (or both) since 2021 .
The existence of drug-resistant TB indeed enhances the difficulty in preventing TB transmission. Through the Direct Observe Treatment (DOTs) and MDR-TB project (DOTS-Plus), drug compliance and medical availability have been greatly enhanced . From WHO global data report, there were 480,000 and 201,997 MDR-TB cases in 2013 and 2019, respectively. The total of drug resistant TB cases in 2020 were declined to 157,903. This result is similar with a large reduction (18%) in the total number of newly diagnosed TB cases between 2019 and 2020 . In Taiwan, MDR-TB has become a notifiable disease since 2006. The drug resistant rate in 2006 was higher than those reported by the third TB global drug resistance surveillance . Implementation of the Multidrug-resistant Tuberculosis Consortium (TMTC) with DOTS-Plus program successfully reduces the incidence of MDR-TB continuously.
COVID-19, a novel pandemic disease, has claimed millions of lives since end of 2019. Its transmission is highly related to the spreading of its key pathogen, namely SARS-CoV-2 . The main mode by which people are infected with SARS-CoV-2, similar to TB, is exposed to air droplets carrying the pathogen. These various-sized droplets are produced during exhalation, such as quiet breathing, singing, speaking, coughing, sneezing or exercise [17, 18, 19, 20].
Since 2019, all of the governments from different countries have paid much effort to the prevention of COVID-19 transmission by several restrictive and self-prevention policies, such as mask wearing, adaptation or closure of schools and businesses, limitations and restrictions on public and private gatherings, restrictions on domestic movement, international travel restrictions, and so on . In Taiwan, most were imported cases until May, 2021, an outbreak of local cases from northern Taiwan . The strict policies of the country border control were effective to prevent the viral transmission from imported cases. The strategies of limiting gatherings, restricting domestic movement, and facial mask wearing successfully curb this regional outbreak in Taiwan.
Based on previous reviews and researches, MTB could be transmitted by various-sized droplets, from large to fine or aerosol particles . Mask wearing, surgical masks or N95 respirators, plays a crucial role in impeding the entrance of these contaminated droplets. The COVID-19 epidemic in 2020-21 provided an opportunity to address whether the transmission of MTB could be influenced by mandatory mask wearing and social distancing adopted by COVID-19 prevention measures during this specific period of COVID-19 pandemic. Moreover, the health care capacities and resources are largely occupied and consumed respectively during the major COVID-19 epidemic. In one study in Korea, they analyzed the TB case notification rate trends during the COVID-19 pandemic . They revealed that 2020 TB case notification rate in South Korea was the lowest since 2012 (49/100,000) and the case notification rate in 2020 was 16.4% lower than that in 2019. These results may be attributed to social distancing practices and increased TB notification among younger individuals during the COVID-19 pandemic. Their research impressed us whether a similar trend would occur in Taiwan during the COVID-19 pandemic or not. It would also be interesting to see whether the mortality rate of TB, that is related to the health care quality, would be increased or not during this period.