Rhinovirus Incidence Rates Indicate We Are Tired of Non-pharmacological Interventions Against Coronavirus Disease 2019

Abstract

Background: During the coronavirus disease 2019 (COVID-19) pandemic, the incidence of rhinovirus (RV) is inversely related to the intensity of non-pharmacological interventions (NPIs), such as universal mask wearing and physical distancing.

Methods: Using RV surveillance data, changes in the effect of NPIs were investigated in South Korea during the pandemic. The time to the first visible effect of NPIs after the onset of NPIs (T1), time to the maximum effect (T2), and duration of the maximum effect (T3) were measured for each surge. For each week, the RVdiff [(RV incidence during the pandemic) - (RV incidence within 5 years before the pandemic)] was calculated, and number of weeks for RVdiff to be below zero after NPIs (time to RVdiff ≤ 0) and number of weeks RVdiff remains below zero after NPIs (duration of RVdiff ≤ 0) were measured for each surge.

Results: During the study period, four surges of COVID-19 were reported. As the pandemic progressed, T1 and T2 increased, but T3 decreased. Additionally, the "time to RVdiff of ≤ 0" increased and "duration of RVdiff of ≤ 0" decreased. These changes became more pronounced during the third surge (mid-November 2020), before the introduction of the COVID-19 vaccine, and from the emergence of the delta variant.

Conclusion: The effect of NPIs appears slower, the duration of the effect becomes shorter, and the intensity also decreases less than a year after the onset of the pandemic owing to people's exhaustion in implementing NPIs. These findings suggest that the COVID-19 response strategy must be completely overhauled.

Keywords: COVID-19; Non-pharmacological Intervention; Rhinovirus; Time of Effects.

Fig. 1. Weekly numbers of patients with COVID-19 and of persons who received COVID-19 vaccination between the first week of 2020 and the 34th week of 2021 in South Korea. The dark blue line indicates the weekly number of COVID-19 patients. The orange line indicates the weekly proportion of people who received more than one dose of COVID-19 vaccination. The red line indicates the weekly proportion of those who have completed the vaccination schedule. Black circles with white numbers indicate the four COVID-19 surges. Boxes indicate the comments related to the appearance of the delta variant in South Korea. Each week is designated by a four-digit number (YYWW) (e.g., 2012 and 2112 indicate the 12th week of 2020 and 2021, respectively).

COVID-19 = coronavirus disease 2019, SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2.

Fig. 2. (A) Weekly number of patients with COVID-19, weekly positivity rate of RV during the pandemic, and the level of intensity of non-pharmacological interventions against COVID-19 between the first week of 2020 and the 34th week of 2021 in South Korea. (B) Weekly value of RVdiff. The dark blue line indicates the number of COVID-19 patients. The red line indicates the weekly positivity rate of RV during the pandemic. The dotted line indicates the weekly mean positivity rate of RV before the pandemic (2015–2019). RVdiff indicates the difference in the weekly RV positivity rate between the pandemic period and the pre-pandemic period (in Fig. 2A, an example of RVdiff is introduced). The three boxes indicate the time to the first visible effect (T1), time to the maximum effect (T2), and duration of the maximum effect (T3) of non-pharmaceutical interventions implemented in each COVID-19 surge. Each week is designated by a four-digit number (YYWW) (e.g., 2012 and 2112 indicate the 12th week of 2020 and 2021, respectively).

COVID-19 = coronavirus disease 2019, RV = rhinovirus.

Fig. 3. Weekly number of patients with COVID-19, weekly positivity rate of human BOV during the pandemic, and the level of intensity of non-pharmacological interventions against COVID-19 between the first week of 2020 and the 34th week of 2021 in South Korea. The dark blue line indicates the number of COVID-19 patients. The orange line indicates the weekly positivity rate of BOV during the pandemic. The dotted line indicates the weekly mean proportion of BOV before the pandemic (2015–2019). The horizontal line indicates the maximum value of the weekly mean proportion of BOV before the pandemic. Each week is designated by a four-digit number (YYWW) (e.g., 2012 and 2112 indicate the 12th week of 2020 and 2021, respectively).

COVID-19 = coronavirus disease 2019, BOV = bocavirus.

Fig. 4. Weekly number of patients with COVID-19, weekly positivity rate of ADV during the pandemic, and the level of intensity of non-pharmacological interventions against COVID-19 between the first week of 2020 and the 34th week of 2021 in South Korea. The dark blue line indicates the number of COVID-19 patients. The light blue line indicates the weekly proportion of ADV during the pandemic. The dotted line indicates the weekly mean proportion of ADV before the pandemic (2015–2019). The horizontal line indicates the maximum value of the weekly mean proportion of ADV before the pandemic. Each week is designated by a four-digit number (YYWW) (e.g., 2012 and 2112 indicate the 12th week of 2020 and 2021, respectively).

COVID-19 = coronavirus disease 2019, ADV = adenovirus.