Decline in invasive pneumococcal disease during COVID-19 pandemic in Taiwan.

Dear Editor,

We read with great interest Lim et al's report, which showed a decreased incidence of pneumococcal disease in Singapore during the first 27 weeks in 2020 in the time of COVID-19. Although the collateral benefit of controlling COVID-19 for other common respiratory infectious diseases, such as influenza and tuberculosis in Taiwan have been demonstrated, , the impact of the infection control and policy to prevent COVID-19 outbreak on pneumococcal disease remained unclear. Therefore, this study was conducted to determine whether the incidence of pneumococcal disease in Taiwan would be decreasing as Lim et al's study in Singapore.

In Taiwan, invasive pneumococcal disease (IPD) is a notifiable disease for which reporting is mandatory for all clinicians. Therefore, this study can obtain the case number of patients with IPD used data from open data website of Taiwan's CDC. To compare the case number of IPD during the same period each year, we extracted the monthly cases between January and August from 2015 to 2020.

First, a total of 162 IPD cases were reported during the first 8 months in 2020, By contrast, the accumulative case number within the 8 months ranged from 282 in 2019 to 400 in 2016, which were much higher than that in 2020 (Fig. 1 A). Second, in 2020, the case number of IPD was highest in January (n = 62) and gradually decreased with time, which was lowest in May (n = 7) (Fig. 1B).

Fig. 1

(A) Accumulative case number from 2015 to 2020, (B) Monthly case number in 2020.

In this study, we found the similar phenomena that IPD was decreasing during COVID-19 in Taiwan, like Lim et al's findings in Singapore. The possible explanation could be the strict performance of infection control and policy during COVID-19 pandemic. Since the first case of COVID-19 was identified in January, a total of 498 COVID-19 cases were reported till now and caused seven deaths. To prevent the outbreak of COVID-19, Taiwan authority immediately practiced many infection control measures, particularly mask wearing, hand hygiene and avoid visiting crowd area. Most of these interventions can help prevent the transmission of SARS-CoV-2 via respiratory droplets and may also provide additional benefit in the controlling other respiratory infectious diseases, such as pneumococcal disease, which was demonstrated here.

Although many confounding factors, such as vaccine strategy or under-report of IPD during COVID-19 pandemic were not evaluated in this study, our findings was consistent with Singapore's study suggest that strictly performance of infection control and policy not only mitigate the threaten of COVID-19 but also reduce the burden of other respiratory infections disease – invasive pneumococcal diseases.